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diff --git a/nauty/nautinv.c b/nauty/nautinv.c
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+/*****************************************************************************
+*                                                                            *
+*  Vertex-invariants source file for nauty 2.8.                              *
+*                                                                            *
+*   Copyright (1989-2022) Brendan McKay.  All rights reserved.               *
+*   Subject to waivers and disclaimers in nauty.h.                           *
+*                                                                            *
+*   CHANGE HISTORY                                                           *
+*       13-Mar-90 : initial release for version 1.5                          *
+*       10-Nov-90 : changes for version 1.6 :                                *
+*                 - added dummy routine nautinv_null()                       *
+*       27-Aug-92 : renamed to version 1.7, no changes to this file          *
+*        5-Jun-93 : renamed to version 1.7+, no changes to this file         *
+*       18-Aug-93 : renamed to version 1.8, no changes to this file          *
+*       17-Sep-93 : changes for version 1.9 :                                *
+*                 - added invariant routine adjacencies()                    *
+*       20-Jun-96 : changes for version 2.0 :                                *
+*                 - added invariants cellfano() and cellfano2()              *
+*       11-Jul-96 - added dynamic allocation                                 *
+*       21-Oct-98 - use shortish in place of short for BIGNAUTY              *
+*        9-Jan-00 - added nautinv_check()                                    *
+*       12-Feb-00 - minor code formatting                                    *
+*       16-Nov-00 - made changes listed in nauty.h                           *
+*       22-Apr-01 : changes for version 2.1 :                                *
+*                 - made all large dynamic memory external to routines       *
+*                 - added nautinv_freedyn() to free all such memory          *
+*                 - include nautinv.h rather than naututil.h                 *
+*                 - removed nautinv_null()                                   *
+*                 - added code to facilitate compilation into Magma          *
+*                 - removed EXTDEFS                                          *
+*       12-Jul-01 - use invararg in distances()                              *
+*                 - fixed comments in ind and cliq routines                  *
+*       21-Nov-01 : use NAUTYREQUIRED in nautinv_check()                     *
+*       10-Dec-06 : remove BIGNAUTY                                          *
+*       10-Nov-09 : remove types shortish and permutation                    *
+*       23-Nov-09 : add refinvar()                                           *
+*       12-Jun-10 : fixed identical errors in cellcliq() and cellind()       *
+*       15-Jan-12 : add TLS_ATTR attributes                                  *
+*       23-Aug-12 : fix getbigcells(), thanks to Fatih Demirkale             *
+*       23-Jan-13 : add some parens to satisfy icc                           *
+*                                                                            *
+*****************************************************************************/
+
+#define ONE_WORD_SETS
+#include "nautinv.h"
+
+#if  MAXM==1
+#define M 1
+#else
+#define M m
+#endif
+
+#define MASH(l,i) ((((l) ^ 056345) + (i)) & 077777)
+    /* : expression whose long value depends only on long l and int/long i.
+         Anything goes, preferably non-commutative. */
+
+#define CLEANUP(l) ((int)((l) % 077777))
+    /* : expression whose value depends on long l and is less than 077777
+         when converted to int then short.  Anything goes. */
+
+#define ACCUM(x,y)   x = (((x) + (y)) & 077777)
+    /* : must be commutative. */
+
+static const int fuzz1[] = {037541,061532,005257,026416};
+static const int fuzz2[] = {006532,070236,035523,062437};
+
+#define FUZZ1(x) ((x) ^ fuzz1[(x)&3])
+#define FUZZ2(x) ((x) ^ fuzz2[(x)&3])
+
+#define MAXCLIQUE 10    /* max clique size for cliques() and maxindset() */
+
+#if MAXN
+static TLS_ATTR int workshort[MAXN+2];
+static TLS_ATTR int vv[MAXN],ww[MAXN];
+static TLS_ATTR int workperm[MAXN];
+static TLS_ATTR int bucket[MAXN+2];
+static TLS_ATTR int count[MAXN];
+static TLS_ATTR set workset[MAXM];
+static TLS_ATTR set w01[MAXM],w02[MAXM],w03[MAXM],w12[MAXM],w13[MAXM],w23[MAXM];
+static TLS_ATTR set pt0[MAXM],pt1[MAXM],pt2[MAXM];
+static TLS_ATTR set wss[MAXCLIQUE-1][MAXM];
+static TLS_ATTR set ws1[MAXM],ws2[MAXM];
+#else
+DYNALLSTAT(int,workshort,workshort_sz);
+DYNALLSTAT(int,vv,vv_sz);
+DYNALLSTAT(int,ww,ww_sz);
+DYNALLSTAT(int,workperm,workperm_sz);
+DYNALLSTAT(int,bucket,bucket_sz);
+DYNALLSTAT(int,count,count_sz);
+DYNALLSTAT(set,ws1,ws1_sz);
+DYNALLSTAT(set,ws2,ws2_sz);
+DYNALLSTAT(set,workset,workset_sz);
+DYNALLSTAT(set,w01,w01_sz);
+DYNALLSTAT(set,w02,w02_sz);
+DYNALLSTAT(set,w03,w03_sz);
+DYNALLSTAT(set,w12,w12_sz);
+DYNALLSTAT(set,w13,w13_sz);
+DYNALLSTAT(set,w23,w23_sz);
+DYNALLSTAT(set,pt0,pt0_sz);
+DYNALLSTAT(set,pt1,pt1_sz);
+DYNALLSTAT(set,pt2,pt2_sz);
+DYNALLSTAT(set,wss,wss_sz);
+#endif
+
+/* aproto: header new_nauty_protos.h */
+
+/*****************************************************************************
+*                                                                            *
+*  This file contains a number of procedures which compute vertex-invariants *
+*  for stronger partition refinement.   Since entirely different             *
+*  vertex-invariants seem to work better for different types of graph, we    *
+*  cannot do more than give a small collection of representative examples.   *
+*  Any serious computations with difficult graphs may well need to use       *
+*  specially-written vertex-invariants.  The use of vertex-invariants        *
+*  procedures is supported by nauty from version 1.5 onwards, via the        *
+*  options userinvarproc, mininvarlevel, maxinvarlevel and invararg.         *
+*  The meaning of these fields in detail are as follows:                     *
+*     userinvarproc  is the address of the vertex-invariant procedure.  If   *
+*                    no vertex-invariants is required, this field should     *
+*                    have the value NULL.                                    *
+*     maxinvarlevel  The absolute value of this is the maximum level in the  *
+*                    search tree at which the vertex-invariant will be       *
+*                    computed.  The root of the tree is at level 1, so the   *
+*                    vertex-invariant will not be invoked at all if          *
+*                    maxinvarlevel==0.  Negative values of maxinvarlevel     *
+*                    request nauty to not compute the vertex-invariant at    *
+*                    a level greater than that of the earliest node (if any) *
+*                    on the path to the first leaf of the search tree at     *
+*                    which the vertex-invariant refines the partition.       *
+*     mininvarlevel  The absolute value of this is the minimum level in the  *
+*                    search tree at which the vertex-invariant will be       *
+*                    computed.  The root of the tree is at level 1, so there *
+*                    is no effective limit if mininvarlevel is -1, 0 or 1.   *
+*                    Negative values of mininvarlevel request nauty to not   *
+*                    compute the vertex-invariant at a level less than       *
+*                    that of the earliest node (if any) on the path to the   *
+*                    first leaf of the search tree at which the              *
+*                    vertex-invariant refines the partition.                 *
+*     invararg       is passed to the vertex-invariant procedure via the     *
+*                    argument of the same name.  It can be used by the       *
+*                    procedure for any purpose.                              *
+*  Note that negative values of maxinvarlevel and mininvarlevel make the     *
+*  canonical labelling invalid, but can speed automorphism group finding.    *
+*  Nauty already knows this and takes their absolute values.                 *
+*                                                                            *
+*  A vertex-invariant must be declared thus:                                 *
+*  void invarproc(g,lab,ptn,level,numcells,tvpos,invar,invararg,digraph,m,n) *
+*  All of these arguments must be treated as read-only except for invar.     *
+*  g        : the graph, exactly as passed to nauty()                        *
+*  lab,ptn  : the current partition nest (see nauty.h for the format)        *
+*  level    : the level of this node in the search tree.                     *
+*  numcells : the number of cells in the partition at this node.             *
+*  tvpos    : the index in (lab,ptn) of one cell in the partition.           *
+*             If level <= 1, the cell will be the first fragment of the      *
+*             first active cell (as provided by the initial call to nauty),  *
+*             or the first cell, if there were no active cells.              *
+*             If level > 1, the cell will be the singleton cell which was    *
+*             created to make this node of the search tree from its parent.  *
+*  invararg : a copy of options.invararg                                     *
+*  digraph  : a copy of options.digraph                                      *
+*  m,n      : size parameters as passed to nauty()                           *
+*  invar    : an array to return the answer in.   The procedure must put in  *
+*             each invar[i]  (0 <= i < n)  an invariant of the 6-tuple       *
+*             (<vertex i>,g,<the partition nest to this level>,level,        *
+*               invararg,digraph)                                            *
+*             Note that invar[] is declared as an int array.  Since the      *
+*             absolute value of the invariant is irrelevant, only the        *
+*             comparative values, any short, int or long value can be        *
+*             assigned to the entries of invar[] without fear.  However,     *  
+*             you should assign a value less than 077777 to ensure machine-  *
+*             independence of the canonical labelling.                       *
+*                                                                            *
+*  The refinement procedure has already been called before the invariant     *
+*  procedure is called.  That means that the partition is equitable if       *
+*  digraph==FALSE.                                                           *
+*                                                                            *
+*****************************************************************************/
+
+/*****************************************************************************
+*                                                                            *
+*  twopaths() assigns to each vertex v the sum of the weights of each vertex *
+*  which can be reached from v along a walk of length two (including itself  *
+*  usually).  The weight of each vertex w is defined as the ordinal number   *
+*  of the cell containing w, starting at 1 for the first cell.               *
+*                                                                            *
+*****************************************************************************/
+
+void
+twopaths(graph *g, int *lab, int *ptn, int level, int numcells, int tvpos,
+         int *invar, int invararg, boolean digraph, int m, int n)
+{
+    int i,v,w;
+    int wt;
+    set *gv,*gw;
+
+#if !MAXN
+    DYNALLOC1(set,workset,workset_sz,m,"twopaths");
+    DYNALLOC1(int,workshort,workshort_sz,n+2,"twopaths");
+#endif
+
+    wt = 1;
+    for (i = 0; i < n; ++i)
+    {
+        workshort[lab[i]] = wt;
+        if (ptn[i] <= level) ++wt;
+    }
+
+    for (v = 0, gv = (set*)g; v < n; ++v, gv += M)
+    {
+        EMPTYSET(workset,m);
+        w = -1;
+        while ((w = nextelement(gv,M,w)) >= 0)
+        {
+            gw = GRAPHROW(g,w,m);
+            for (i = M; --i >= 0;) UNION(workset[i],gw[i]);
+        }
+        wt = 0;
+        w = -1;
+        while ((w = nextelement(workset,M,w)) >= 0) ACCUM(wt,workshort[w]);
+        invar[v] = wt;
+    }
+}
+
+/*****************************************************************************
+*                                                                            *
+*  quadruples() assigns to each vertex v a value depending on the set of     *
+*  weights w(v,v1,v2,v3), where w(v,v1,v2,v3) depends on the number of       *
+*  vertices adjacent to an odd number of {v,v1,v2,v3}, and to the cells      *
+*  that v,v1,v2,v3 belong to.  {v,v1,v2,v3} are permitted to range over all  *
+*  distinct 4-tuples which contain at least one member in the cell tvpos.    *
+*                                                                            *
+*****************************************************************************/
+
+void
+quadruples(graph *g, int *lab, int *ptn, int level, int numcells, int tvpos,
+           int *invar, int invararg, boolean digraph, int m, int n)
+{
+    int i,pc;
+    setword sw;
+    set *gw;
+    int wt;
+    int v,iv,v1,v2,v3;
+    set *gv;
+    long wv,wv1,wv2,wv3;
+
+#if !MAXN
+    DYNALLOC1(int,workshort,workshort_sz,n+2,"quadruples");
+    DYNALLOC1(set,ws1,ws1_sz,m,"quadruples");
+    DYNALLOC1(set,workset,workset_sz,m,"quadruples");
+#endif
+
+    for (i = n; --i >= 0;) invar[i] = 0;
+
+    wt = 1;
+    for (i = 0; i < n; ++i)
+    {
+        workshort[lab[i]] = FUZZ2(wt);
+        if (ptn[i] <= level) ++wt;
+    }
+
+    iv = tvpos - 1;
+    do
+    {
+         v = lab[++iv];
+         gv = GRAPHROW(g,v,m);
+         wv = workshort[v];
+         for (v1 = 0; v1 < n-2; ++v1)
+         {
+            wv1 = workshort[v1];
+            if (wv1 == wv && v1 <= v) continue;
+            wv1 += wv;
+            gw = GRAPHROW(g,v1,m);
+            for (i = M; --i >= 0;) workset[i] = gv[i] ^ gw[i];
+            for (v2 = v1+1; v2 < n-1; ++v2)
+            {
+                wv2 = workshort[v2];
+                if (wv2 == wv && v2 <= v) continue;
+                wv2 += wv1;
+                gw = GRAPHROW(g,v2,m);
+                for (i = M; --i >= 0;) ws1[i] = workset[i] ^ gw[i];
+                for (v3 = v2+1; v3 < n; ++v3)
+                {
+                    wv3 = workshort[v3];
+                    if (wv3 == wv && v3 <= v) continue;
+                    wv3 += wv2;
+                    gw = GRAPHROW(g,v3,m);
+                    pc = 0;
+                    for (i = M; --i >= 0;)
+                        if ((sw = ws1[i] ^ gw[i]) != 0) pc += POPCOUNT(sw);
+                    wt = (FUZZ1(pc)+wv3) & 077777;
+                    wt = FUZZ2(wt);
+                    ACCUM(invar[v],wt);
+                    ACCUM(invar[v1],wt);
+                    ACCUM(invar[v2],wt);
+                    ACCUM(invar[v3],wt);
+                }
+            }
+        }
+    }
+    while (ptn[iv] > level);
+}
+
+/*****************************************************************************
+*                                                                            *
+*  triples() assigns to each vertex v a value depending on the set of        *
+*  weights w(v,v1,v2), where w(v,v1,v2) depends on the number of vertices    *
+*  adjacent to an odd number of {v,v1,v2}, and to the cells that             *
+*  v,v1,v2 belong to.  {v,v1,v2} are permitted to range over all distinct    *
+*  triples which contain at least one member in the cell tvpos.              *
+*                                                                            *
+*****************************************************************************/
+
+void
+triples(graph *g, int *lab, int *ptn, int level, int numcells, int tvpos,
+        int *invar, int invararg, boolean digraph, int m, int n)
+{
+    int i,pc;
+    setword sw;
+    set *gw;
+    int wt;
+    int v,iv,v1,v2;
+    set *gv;
+    long wv,wv1,wv2;
+
+#if !MAXN
+    DYNALLOC1(set,workset,workset_sz,m,"triples");
+    DYNALLOC1(int,workshort,workshort_sz,n+2,"triples");
+#endif
+
+    for (i = n; --i >= 0;) invar[i] = 0;
+
+    wt = 1;
+    for (i = 0; i < n; ++i)
+    {
+        workshort[lab[i]] = FUZZ1(wt);
+        if (ptn[i] <= level) ++wt;
+    }
+
+    iv = tvpos - 1;
+    do
+    {
+         v = lab[++iv];
+         gv = GRAPHROW(g,v,m);
+         wv = workshort[v];
+         for (v1 = 0; v1 < n-1; ++v1)
+         {
+            wv1 = workshort[v1];
+            if (wv1 == wv && v1 <= v) continue;
+            wv1 += wv;
+            gw = GRAPHROW(g,v1,m);
+            for (i = M; --i >= 0;) workset[i] = gv[i] ^ gw[i];
+            for (v2 = v1+1; v2 < n; ++v2)
+            {
+                wv2 = workshort[v2];
+                if (wv2 == wv && v2 <= v) continue;
+                wv2 += wv1;
+                gw = GRAPHROW(g,v2,m);
+                pc = 0;
+                for (i = M; --i >= 0;)
+                    if ((sw = workset[i] ^ gw[i]) != 0) pc += POPCOUNT(sw);
+                wt = (FUZZ1(pc)+wv2) & 077777;
+                wt = FUZZ2(wt);
+                ACCUM(invar[v],wt);
+                ACCUM(invar[v1],wt);
+                ACCUM(invar[v2],wt);
+            }
+        }
+    }
+    while (ptn[iv] > level);
+}
+
+/*****************************************************************************
+*                                                                            *
+*  adjtriang() assigns to each vertex v a value depending on the numbers     *
+*  of common neighbours between each pair {v1,v2} of neighbours of v, and    *
+*  which cells v1 and v2 lie in.  The vertices v1 and v2 must be adjacent    *
+*  if invararg == 0 and not adjacent if invararg == 1.                       *
+*                                                                            *
+*****************************************************************************/
+
+void
+adjtriang(graph *g, int *lab, int *ptn, int level, int numcells, int tvpos,
+          int *invar, int invararg, boolean digraph, int m, int n)
+{
+    int j,pc;
+    setword sw;
+    set *gi;
+    int wt;
+    int i,v1,v2;
+    boolean v1v2;
+    set *gv1,*gv2;
+
+#if !MAXN
+    DYNALLOC1(set,workset,workset_sz,m,"adjtriang");
+    DYNALLOC1(int,workshort,workshort_sz,n+2,"adjtriang");
+#endif
+
+    for (i = n; --i >= 0;) invar[i] = 0;
+
+    wt = 1;
+    for (i = 0; i < n; ++i)
+    {
+        workshort[lab[i]] = FUZZ1(wt);
+        if (ptn[i] <= level) ++wt;
+    }
+
+    for (v1 = 0, gv1 = g; v1 < n; ++v1, gv1 += M)
+    {
+        for (v2 = (digraph ? 0 : v1+1); v2 < n; ++v2)
+        {
+            if (v2 == v1) continue;
+            v1v2 = (ISELEMENT(gv1,v2) != 0);
+            if ((invararg == 0 && !v1v2)
+                     || (invararg == 1 && v1v2)) continue;
+            wt = workshort[v1];
+            ACCUM(wt,workshort[v2]);
+            ACCUM(wt,v1v2);
+
+            gv2 = GRAPHROW(g,v2,m);
+            for (i = M; --i >= 0;) workset[i] = gv1[i] & gv2[i];
+            i = -1;
+            while ((i = nextelement(workset,M,i)) >= 0)
+            {
+                pc = 0;
+                gi = GRAPHROW(g,i,m);
+                for (j = M; --j >= 0;)
+                    if ((sw = workset[j] & gi[j]) != 0) pc += POPCOUNT(sw);
+                pc = (pc + wt) & 077777;
+                ACCUM(invar[i],pc);
+            }
+        }
+    }
+}
+
+/*****************************************************************************
+*                                                                            *
+*  getbigcells(ptn,level,minsize,bigcells,cellstart,cellsize,n) is an        *
+*  auxiliary procedure to make a list of all the large cells in the current  *
+*  partition.  On entry, ptn, level and n have their usual meanings,         *
+*  while minsize is the smallest size of an interesting cell.  On return,    *
+*  bigcells is the number of cells of size at least minsize, cellstart[0...] *
+*  contains their starting positions in ptn, and cellsize[0...] contain      *
+*  their sizes.  These two arrays are in increasing order of cell size,      *
+*  then position.                                                            *
+*                                                                            *
+*****************************************************************************/
+
+void
+getbigcells(int *ptn, int level, int minsize, int *bigcells,
+            int *cellstart, int *cellsize, int n)
+{
+    int cell1,cell2,j;
+    int si,st;
+    int bc,i,h;
+
+    bc = 0;
+    for (cell1 = 0; cell1 < n; cell1 = cell2 + 1)
+    {
+        for (cell2 = cell1; ptn[cell2] > level; ++cell2) {}
+
+        if (cell2 >= cell1 + minsize - 1)
+        {
+            cellstart[bc] = cell1;
+            cellsize[bc] = cell2 - cell1 + 1;
+            ++bc;
+        }
+    }
+    *bigcells = bc;
+
+    j = bc / 3;
+    h = 1;
+    do
+        h = 3 * h + 1;
+    while (h < j);
+
+    do                      /* shell sort */
+    {
+        for (i = h; i < bc; ++i)
+        {
+            st = cellstart[i];
+            si = cellsize[i];
+            for (j = i; cellsize[j-h] > si ||
+                        (cellsize[j-h] == si && cellstart[j-h] > st); )
+            {
+                cellsize[j] = cellsize[j-h];
+                cellstart[j] = cellstart[j-h];
+                if ((j -= h) < h) break;
+            }
+            cellsize[j] = si;
+            cellstart[j] = st;
+        }
+        h /= 3;
+    }
+    while (h > 0);
+}
+
+/*****************************************************************************
+*                                                                            *
+*  celltrips() assigns to each vertex v a value depending on the set of      *
+*  weights w(v,v1,v2), where w(v,v1,v2) depends on the number of vertices    *
+*  adjacent to an odd number of {v,v1,v2}.  {v,v1,v2} are  constrained to    *
+*  belong to the same cell.  We try the cells in increasing order of size,   *
+*  and stop as soon as any cell splits.                                      *
+*                                                                            *
+*****************************************************************************/
+
+void
+celltrips(graph *g, int *lab, int *ptn, int level, int numcells, int tvpos,
+          int *invar, int invararg, boolean digraph, int m, int n)
+{
+    int i,pc;
+    setword sw;
+    set *gw;
+    int wt;
+    int v,iv,v1,iv1,v2,iv2;
+    int icell,bigcells,cell1,cell2;
+    int *cellstart,*cellsize;
+    set *gv;
+
+#if !MAXN
+    DYNALLOC1(set,workset,workset_sz,m,"celltrips");
+    DYNALLOC1(int,workshort,workshort_sz,n+2,"celltrips");
+#endif
+
+    for (i = n; --i >= 0;) invar[i] = 0;
+
+    cellstart = workshort;
+    cellsize = workshort + (n/2);
+    getbigcells(ptn,level,3,&bigcells,cellstart,cellsize,n);
+
+    for (icell = 0; icell < bigcells; ++icell)
+    {
+        cell1 = cellstart[icell];
+        cell2 = cell1 + cellsize[icell] - 1;
+        for (iv = cell1; iv <= cell2 - 2; ++iv)
+        {
+            v = lab[iv];
+            gv = GRAPHROW(g,v,m);
+            for (iv1 = iv + 1; iv1 <= cell2 - 1; ++iv1)
+            {
+                v1 = lab[iv1];
+                gw = GRAPHROW(g,v1,m);
+                for (i = M; --i >= 0;) workset[i] = gv[i] ^ gw[i];
+                for (iv2 = iv1 + 1; iv2 <= cell2; ++iv2)
+                {
+                    v2 = lab[iv2];
+                    gw = GRAPHROW(g,v2,m);
+                    pc = 0;
+                    for (i = M; --i >= 0;)
+                        if ((sw = workset[i] ^ gw[i]) != 0)
+                            pc += POPCOUNT(sw);
+                    wt = FUZZ1(pc);
+                    ACCUM(invar[v],wt);
+                    ACCUM(invar[v1],wt);
+                    ACCUM(invar[v2],wt);
+                }
+            }
+        }
+        wt = invar[lab[cell1]];
+        for (i = cell1 + 1; i <= cell2; ++i)
+            if (invar[lab[i]] != wt) return;
+    }
+}
+
+/*****************************************************************************
+*                                                                            *
+*  cellquads() assigns to each vertex v a value depending on the set of      *
+*  weights w(v,v1,v2,v3), where w(v,v1,v2,v3) depends on the number of       *
+*  vertices adjacent to an odd number of {v,v1,v2,v3}.  {v,v1,v2,v3} are     *
+*  constrained to belong to the same cell.  We try the cells in increasing   *
+*  order of size, and stop as soon as any cell splits.                       *
+*                                                                            *
+*****************************************************************************/
+
+void
+cellquads(graph *g, int *lab, int *ptn, int level, int numcells, int tvpos,
+          int *invar, int invararg, boolean digraph, int m, int n)
+{
+    int i,pc;
+    setword sw;
+    set *gw;
+    int wt;
+    int v,iv,v1,iv1,v2,iv2,v3,iv3;
+    int icell,bigcells,cell1,cell2;
+    int *cellstart,*cellsize;
+    set *gv;
+
+#if !MAXN
+    DYNALLOC1(set,workset,workset_sz,m,"cellquads");
+    DYNALLOC1(int,workshort,workshort_sz,n+2,"cellquads");
+    DYNALLOC1(set,ws1,ws1_sz,m,"cellquads");
+#endif
+
+    for (i = n; --i >= 0;) invar[i] = 0;
+
+    cellstart = workshort;
+    cellsize = workshort + (n/2);
+    getbigcells(ptn,level,4,&bigcells,cellstart,cellsize,n);
+
+    for (icell = 0; icell < bigcells; ++icell)
+    {
+        cell1 = cellstart[icell];
+        cell2 = cell1 + cellsize[icell] - 1;
+        for (iv = cell1; iv <= cell2 - 3; ++iv)
+        {
+            v = lab[iv];
+            gv = GRAPHROW(g,v,m);
+            for (iv1 = iv + 1; iv1 <= cell2 - 2; ++iv1)
+            {
+                v1 = lab[iv1];
+                gw = GRAPHROW(g,v1,m);
+                for (i = M; --i >= 0;) workset[i] = gv[i] ^ gw[i];
+                for (iv2 = iv1 + 1; iv2 <= cell2 - 1; ++iv2)
+                {
+                    v2 = lab[iv2];
+                    gw = GRAPHROW(g,v2,m);
+                    for (i = M; --i >= 0;) ws1[i] = workset[i] ^ gw[i];
+                    for (iv3 = iv2 + 1; iv3 <= cell2; ++iv3)
+                    {
+                        v3 = lab[iv3];
+                        gw = GRAPHROW(g,v3,m);
+                        pc = 0;
+                        for (i = M; --i >= 0;)
+                            if ((sw = ws1[i] ^ gw[i]) != 0)
+                                pc += POPCOUNT(sw);
+                        wt = FUZZ1(pc);
+                        ACCUM(invar[v],wt);
+                        ACCUM(invar[v1],wt);
+                        ACCUM(invar[v2],wt);
+                        ACCUM(invar[v3],wt);
+                    }
+                }
+            }
+        }
+        wt = invar[lab[cell1]];
+        for (i = cell1 + 1; i <= cell2; ++i)
+            if (invar[lab[i]] != wt) return;
+    }
+}
+
+/*****************************************************************************
+*                                                                            *
+*  cellquins() assigns to each vertex v a value depending on the set of      *
+*  weights w(v,v1,v2,v3,v4), where w(v,v1,v2,v3,v4) depends on the number    *
+*  of vertices adjacent to an odd number of {v,v1,v2,v3,v4}.                 *
+*  {v,v1,v2,v3,v4} are constrained to belong to the same cell.  We try the   *
+*  cells in increasing order of size, and stop as soon as any cell splits.   *
+*                                                                            *
+*****************************************************************************/
+
+void
+cellquins(graph *g, int *lab, int *ptn, int level, int numcells, int tvpos,
+          int *invar, int invararg, boolean digraph, int m, int n)
+{
+    int i,pc;
+    setword sw;
+    set *gw;
+    int wt;
+    int v,iv,v1,iv1,v2,iv2,v3,iv3,v4,iv4;
+    int icell,bigcells,cell1,cell2;
+    int *cellstart,*cellsize;
+    set *gv;
+
+#if !MAXN
+    DYNALLOC1(set,workset,workset_sz,m,"cellquins");
+    DYNALLOC1(int,workshort,workshort_sz,n+2,"cellquins");
+    DYNALLOC1(set,ws1,ws1_sz,m,"cellquins");
+    DYNALLOC1(set,ws2,ws2_sz,m,"cellquins");
+#endif
+
+    for (i = n; --i >= 0;) invar[i] = 0;
+
+    cellstart = workshort;
+    cellsize = workshort + (n/2);
+    getbigcells(ptn,level,5,&bigcells,cellstart,cellsize,n);
+
+    for (icell = 0; icell < bigcells; ++icell)
+    {
+        cell1 = cellstart[icell];
+        cell2 = cell1 + cellsize[icell] - 1;
+        for (iv = cell1; iv <= cell2 - 4; ++iv)
+        {
+            v = lab[iv];
+            gv = GRAPHROW(g,v,m);
+            for (iv1 = iv + 1; iv1 <= cell2 - 3; ++iv1)
+            {
+                v1 = lab[iv1];
+                gw = GRAPHROW(g,v1,m);
+                for (i = M; --i >= 0;) workset[i] = gv[i] ^ gw[i];
+                for (iv2 = iv1 + 1; iv2 <= cell2 - 2; ++iv2)
+                {
+                    v2 = lab[iv2];
+                    gw = GRAPHROW(g,v2,m);
+                    for (i = M; --i >= 0;) ws1[i] = workset[i] ^ gw[i];
+                    for (iv3 = iv2 + 1; iv3 <= cell2 - 1; ++iv3)
+                    {
+                        v3 = lab[iv3];
+                        gw = GRAPHROW(g,v3,m);
+                        for (i = M; --i >= 0;) ws2[i] = ws1[i] ^ gw[i];
+                        for (iv4 = iv3 + 1; iv4 <= cell2; ++iv4)
+                        {
+                            v4 = lab[iv4];
+                            gw = GRAPHROW(g,v4,m);
+                            pc = 0;
+                            for (i = M; --i >= 0;)
+                                if ((sw = ws2[i] ^ gw[i]) != 0)
+                                    pc += POPCOUNT(sw);
+                            wt = FUZZ1(pc);
+                            ACCUM(invar[v],wt);
+                            ACCUM(invar[v1],wt);
+                            ACCUM(invar[v2],wt);
+                            ACCUM(invar[v3],wt);
+                            ACCUM(invar[v4],wt);
+                        }
+                    }
+                }
+            }
+        }
+        wt = invar[lab[cell1]];
+        for (i = cell1 + 1; i <= cell2; ++i)
+            if (invar[lab[i]] != wt) return;
+    }
+}
+
+/*****************************************************************************
+*                                                                            *
+*  uniqinter(s1,s2,m) returns the number in both sets if it is unique,       *
+*  or -1 if there is none or it is not unique.                               *
+*****************************************************************************/
+
+static int
+uniqinter(set *s1, set *s2, int m)
+{
+    int i,j;
+    setword w;
+
+    for (i = 0; i < M; ++i)
+    {
+        if ((w = s1[i] & s2[i]) != 0)
+        {
+            j = FIRSTBITNZ(w);
+            if (w != BITT[j]) return -1;
+            j += TIMESWORDSIZE(i);
+            for (++i; i < M; ++i)
+                if (s1[i] & s2[i]) return -1;
+            return j;
+        }
+    }
+    return -1;
+}
+
+/*****************************************************************************
+*                                                                            *
+*  cellfano2() assigns to each vertex v a value depending on the set of      *
+*  weights w(v,v1,v2,v3), where w(v,v1,v2,v3) depends on the number of       *
+*  fano-plane analogues containing {v,v1,v2,v3}.  {v,v1,v2,v3} are           *
+*  constrained to belong to the same cell and being independent and          *
+*  non-collinear.  We try the cells in increasing order of size, and stop    *
+*  as soon as any cell splits.                                               *
+*                                                                            *
+*****************************************************************************/
+
+void 
+cellfano2(graph *g, int *lab, int *ptn, int level, int numcells, int tvpos,
+          int *invar, int invararg, boolean digraph, int m, int n)
+{
+    int i,pc;
+    setword sw;
+    int wt;
+    int v0,v1,v2,v3,iv0,iv1,iv2,iv3;
+    int icell,bigcells,cell1,cell2;
+    int *cellstart,*cellsize;
+    int nw,x01,x02,x03,x12,x13,x23;
+    int pnt0,pnt1,pnt2;
+    set *gv0,*gv1,*gv2,*gv3;
+    set *gp0,*gp1,*gp2;
+
+#if !MAXN
+    DYNALLOC1(int,workshort,workshort_sz,n+2,"cellfano2");
+    DYNALLOC1(int,vv,vv_sz,n,"cellfano2");
+    DYNALLOC1(int,ww,ww_sz,n,"cellfano2");
+#endif
+
+    for (i = n; --i >= 0;) invar[i] = 0;
+
+    cellstart = workshort;
+    cellsize = workshort + (n/2);
+    getbigcells(ptn,level,4,&bigcells,cellstart,cellsize,n);
+
+    for (icell = 0; icell < bigcells; ++icell)
+    {
+        cell1 = cellstart[icell];
+        cell2 = cell1 + cellsize[icell] - 1;
+        for (iv0 = cell1; iv0 <= cell2 - 3; ++iv0)
+        {
+            v0 = lab[iv0];
+            gv0 = GRAPHROW(g,v0,m);
+            nw = 0;
+            for (iv1 = iv0 + 1; iv1 <= cell2; ++iv1)
+            {
+                v1 = lab[iv1];
+                if (ISELEMENT(gv0,v1)) continue;
+                if ((x01 = uniqinter(gv0,GRAPHROW(g,v1,m),m)) < 0) continue;
+                vv[nw] = v1;
+                ww[nw] = x01;
+                ++nw;
+            }
+
+            for (iv1 = 0; iv1 < nw-2; ++iv1)
+            {
+                v1 = vv[iv1];
+                gv1 = GRAPHROW(g,v1,m);
+                x01 = ww[iv1];
+
+                for (iv2 = iv1 + 1; iv2 < nw-1; ++iv2)
+                {
+                    x02 = ww[iv2];
+                    if (x02 == x01) continue;
+                    v2 = vv[iv2];
+                    if (ISELEMENT(gv1,v2)) continue;
+                    gv2 = GRAPHROW(g,v2,m);
+                    if ((x12 = uniqinter(gv1,gv2,m)) < 0) continue;
+
+                    for (iv3 = iv2 + 1; iv3 < nw; ++iv3)
+                    {
+                        x03 = ww[iv3];
+                        if (x03 == x01 || x03 == x02) continue;
+                        v3 = vv[iv3];
+                        if (ISELEMENT(gv1,v3) || ISELEMENT(gv2,v3))
+                            continue;
+                        gv3 = GRAPHROW(g,v3,m);
+                        if ((x13 = uniqinter(gv1,gv3,m)) < 0) continue;
+                        if ((x23 = uniqinter(gv2,gv3,m)) < 0
+                                               || x23 == x13) continue;
+
+                        if ((pnt0 = uniqinter(GRAPHROW(g,x01,m),
+                                             GRAPHROW(g,x23,m),m)) < 0)
+                            continue;
+                        if ((pnt1 = uniqinter(GRAPHROW(g,x02,m),
+                                             GRAPHROW(g,x13,m),m)) < 0)
+                            continue;
+                        if ((pnt2 = uniqinter(GRAPHROW(g,x03,m),
+                                             GRAPHROW(g,x12,m),m)) < 0)
+                            continue;
+
+                        gp0 = GRAPHROW(g,pnt0,m);
+                        gp1 = GRAPHROW(g,pnt1,m);
+                        gp2 = GRAPHROW(g,pnt2,m);
+
+                        pc = 0;
+                        for (i = M; --i >= 0;)
+                        {
+                            sw = gp0[i] & gp1[i] & gp2[i];
+                            if (sw) pc += POPCOUNT(sw);
+                        }
+                        wt = FUZZ1(pc);
+                        ACCUM(invar[v0],wt);
+                        ACCUM(invar[v1],wt);
+                        ACCUM(invar[v2],wt);
+                        ACCUM(invar[v3],wt);
+                    }
+                }
+            }
+        }
+        wt = invar[lab[cell1]];
+        for (i = cell1 + 1; i <= cell2; ++i)
+            if (invar[lab[i]] != wt) return;
+    }
+}
+
+/*****************************************************************************
+*                                                                            *
+*  setnbhd(g,m,n,w,wn) is an auxiliary routine that sets wn to the union     *
+*  of the neighbours of the vertices in w.                                   *
+*                                                                            *
+*****************************************************************************/
+
+void
+setnbhd(graph *g, int m, int n, set *w, set *wn)
+{
+    int i,j;
+    set *gi;
+
+    i = nextelement(w,M,-1);
+    if (i < 0)
+    {
+        EMPTYSET(wn,M);
+        return;
+    }
+
+    gi = GRAPHROW(g,i,M);
+    for (j = M; --j >= 0;) wn[j] = gi[j];
+
+    while ((i = nextelement(w,M,i)) >= 0)
+    {
+        gi = GRAPHROW(g,i,M);
+        for (j = M; --j >= 0;) wn[j] |= gi[j];
+    }
+}    
+
+/*****************************************************************************
+*                                                                            *
+*  cellfano() assigns to each vertex v a value depending on the set of       *
+*  weights w(v,v1,v2,v3), where w(v,v1,v2,v3) depends on the number of       *
+*  fano-plane analogues containing {v,v1,v2,v3}.  {v,v1,v2,v3} are           *
+*  constrained to belong to the same cell and being independent.  We try     *
+*  the cells in increasing order of size, and stop as soon as any cell       *
+*  splits.                                                                   *
+*                                                                            *
+*****************************************************************************/
+
+void 
+cellfano(graph *g, int *lab, int *ptn, int level, int numcells, int tvpos,
+         int *invar, int invararg, boolean digraph, int m, int n)
+{
+    int i,pc;
+    setword sw;
+    int wt;
+    int v0,v1,v2,v3,iv0,iv1,iv2,iv3;
+    int icell,bigcells,cell1,cell2;
+    int *cellstart,*cellsize;
+    set *gv0,*gv1,*gv2,*gv3;
+
+#if !MAXN
+    DYNALLOC1(int,workshort,workshort_sz,n+2,"cellfano");
+    DYNALLOC1(set,w01,w01_sz,m,"cellfano");
+    DYNALLOC1(set,w02,w02_sz,m,"cellfano");
+    DYNALLOC1(set,w03,w03_sz,m,"cellfano");
+    DYNALLOC1(set,w12,w12_sz,m,"cellfano");
+    DYNALLOC1(set,w13,w13_sz,m,"cellfano");
+    DYNALLOC1(set,w23,w23_sz,m,"cellfano");
+    DYNALLOC1(set,pt0,pt0_sz,m,"cellfano");
+    DYNALLOC1(set,pt1,pt1_sz,m,"cellfano");
+    DYNALLOC1(set,pt2,pt2_sz,m,"cellfano");
+    DYNALLOC1(set,workset,workset_sz,m,"cellfano");
+#else
+#endif
+
+    for (i = n; --i >= 0;) invar[i] = 0;
+
+    cellstart = workshort;
+    cellsize = workshort + (n/2);
+    getbigcells(ptn,level,4,&bigcells,cellstart,cellsize,n);
+
+    for (icell = 0; icell < bigcells; ++icell)
+    {
+        cell1 = cellstart[icell];
+        cell2 = cell1 + cellsize[icell] - 1;
+        for (iv0 = cell1; iv0 <= cell2 - 3; ++iv0)
+        {
+            v0 = lab[iv0];
+            gv0 = GRAPHROW(g,v0,m);
+            for (iv1 = iv0 + 1; iv1 <= cell2 - 2; ++iv1)
+            {
+                v1 = lab[iv1];
+                if (ISELEMENT(gv0,v1)) continue;
+                gv1 = GRAPHROW(g,v1,m);
+                for (i = M; --i >= 0;) workset[i] = gv0[i] & gv1[i];
+                setnbhd(g,m,n,workset,w01);
+
+                for (iv2 = iv1 + 1; iv2 <= cell2 - 1; ++iv2)
+                {
+                    v2 = lab[iv2];
+                    if (ISELEMENT(gv0,v2) || ISELEMENT(gv1,v2))
+                        continue;
+                    gv2 = GRAPHROW(g,v2,m);
+                    for (i = M; --i >= 0;) workset[i] = gv0[i] & gv2[i];
+                    setnbhd(g,m,n,workset,w02);
+                    for (i = M; --i >= 0;) workset[i] = gv1[i] & gv2[i];
+                    setnbhd(g,m,n,workset,w12);
+
+                    for (iv3 = iv2 + 1; iv3 <= cell2; ++iv3)
+                    {
+                        v3 = lab[iv3];
+                        if (ISELEMENT(gv0,v3) || ISELEMENT(gv1,v3) ||
+                                    ISELEMENT(gv2,v3))
+                            continue;
+                        gv3 = GRAPHROW(g,v3,m);
+                        for (i = M; --i >= 0;) workset[i] = gv0[i] & gv3[i];
+                        setnbhd(g,m,n,workset,w03);
+                        for (i = M; --i >= 0;) workset[i] = gv1[i] & gv3[i];
+                        setnbhd(g,m,n,workset,w13);
+                        for (i = M; --i >= 0;) workset[i] = gv2[i] & gv3[i];
+                        setnbhd(g,m,n,workset,w23);
+                    
+                        for (i = M; --i >= 0;) workset[i] = w01[i] & w23[i];
+                        setnbhd(g,m,n,workset,pt0);
+                        for (i = M; --i >= 0;) workset[i] = w03[i] & w12[i];
+                        setnbhd(g,m,n,workset,pt1);
+                        for (i = M; --i >= 0;) workset[i] = w02[i] & w13[i];
+                        setnbhd(g,m,n,workset,pt2);
+                        pc = 0;
+                        for (i = M; --i >= 0;)
+                        {
+                            sw = pt0[i] & pt1[i] & pt2[i];
+                            if (sw) pc += POPCOUNT(sw);
+                        }
+                        wt = FUZZ1(pc);
+                        ACCUM(invar[v0],wt);
+                        ACCUM(invar[v1],wt);
+                        ACCUM(invar[v2],wt);
+                        ACCUM(invar[v3],wt);
+                    }
+                }
+            }
+        }
+        wt = invar[lab[cell1]];
+        for (i = cell1 + 1; i <= cell2; ++i)
+            if (invar[lab[i]] != wt) return;
+    }
+}
+
+/*****************************************************************************
+*                                                                            *
+*  distances() assigns to each vertex v a value depending on the number of   *
+*  vertices at each distance from v, and what cells they lie in.             *
+*  If we find any cell which is split in this manner, we don't try any       *
+*  further cells.                                                            *
+*                                                                            *
+*****************************************************************************/
+
+void
+distances(graph *g, int *lab, int *ptn, int level, int numcells, int tvpos,
+          int *invar, int invararg, boolean digraph, int m, int n)
+{
+    int i;
+    set *gw;
+    int wt;
+    int d,dlim,cell1,cell2,iv,v,w;
+    boolean success;
+
+#if !MAXN
+    DYNALLOC1(set,workset,workset_sz,m,"distances");
+    DYNALLOC1(int,workshort,workshort_sz,n+2,"distances");
+    DYNALLOC1(set,ws1,ws1_sz,m,"distances");
+    DYNALLOC1(set,ws2,ws2_sz,m,"distances"); 
+#endif
+
+    for (i = n; --i >= 0;) invar[i] = 0;
+
+    wt = 1;
+    for (i = 0; i < n; ++i)
+    {
+        workshort[lab[i]] = FUZZ1(wt);
+        if (ptn[i] <= level) ++wt;
+    }
+
+    if (invararg > n || invararg == 0) dlim = n;
+    else                               dlim = invararg+1;
+
+    success = FALSE;
+    for (cell1 = 0; cell1 < n; cell1 = cell2 + 1)
+    {
+        for (cell2 = cell1; ptn[cell2] > level; ++cell2) {}
+        if (cell2 == cell1) continue;
+
+        for (iv = cell1; iv <= cell2; ++iv)
+        {
+            v = lab[iv];
+            EMPTYSET(ws1,m);
+            ADDELEMENT(ws1,v);
+            EMPTYSET(ws2,m);
+            ADDELEMENT(ws2,v);
+            for (d = 1; d < dlim; ++d)
+            {
+                EMPTYSET(workset,m);
+                wt = 0;
+                w = -1;
+                while ((w = nextelement(ws2,M,w)) >= 0)
+                {
+                    gw = GRAPHROW(g,w,m);
+                    ACCUM(wt,workshort[w]);
+                    for (i = M; --i >= 0;) workset[i] |= gw[i];
+                }
+                if (wt == 0) break;
+                ACCUM(wt,d);
+                wt = FUZZ2(wt);
+                ACCUM(invar[v],wt);
+                for (i = M; --i >= 0;)
+                {
+                    ws2[i] = workset[i] & ~ws1[i];
+                    ws1[i] |= ws2[i];
+                }
+            }
+            if (invar[v] != invar[lab[cell1]]) success = TRUE;
+        }
+        if (success) break;
+    }
+}
+
+/*****************************************************************************
+*                                                                            *
+*  indsets() assigns to each vertex v a value depending on which cells the   *
+*  vertices which join v in an independent set lie in.  The size of the      *
+*  independent sets which are used is the smallest of invararg and MAXCLIQUE.*
+*                                                                            *
+*****************************************************************************/
+
+void
+indsets(graph *g, int *lab, int *ptn, int level, int numcells, int tvpos,
+        int *invar, int invararg, boolean digraph, int m, int n)
+{
+    int i;
+    int wt;
+    set *gv;
+    int ss,setsize;
+    int v[MAXCLIQUE];
+    long wv[MAXCLIQUE];
+    set *s0,*s1;
+
+#if !MAXN
+    DYNALLOC1(int,workshort,workshort_sz,n+2,"indsets");
+    DYNALLOC2(set,wss,wss_sz,m,MAXCLIQUE-1,"indsets");
+#endif
+
+    for (i = n; --i >= 0;) invar[i] = 0;
+
+    if (invararg <= 1 || digraph) return;
+
+    if (invararg > MAXCLIQUE) setsize = MAXCLIQUE;
+    else                      setsize = invararg;
+
+    wt = 1;
+    for (i = 0; i < n; ++i)
+    {
+        workshort[lab[i]] = FUZZ2(wt);
+        if (ptn[i] <= level) ++wt;
+    }
+
+    for (v[0] = 0; v[0] < n; ++v[0])
+    {
+        wv[0] = workshort[v[0]];
+        s0 = (set*)wss;
+        EMPTYSET(s0,m);
+        for (i = v[0]+1; i < n; ++i) ADDELEMENT(s0,i);
+        gv = GRAPHROW(g,v[0],m);
+        for (i = M; --i >= 0;) s0[i] &= ~gv[i];
+        ss = 1;
+        v[1] = v[0];
+        while (ss > 0)
+        {
+            if (ss == setsize)
+            {
+                wt = FUZZ1(wv[ss-1]);
+                for (i = ss; --i >= 0;) ACCUM(invar[v[i]],wt);
+                --ss;
+            }
+            else if ((v[ss] = nextelement((set*)wss+M*(ss-1),M,v[ss])) < 0)
+                --ss;
+            else
+            {
+                wv[ss] = wv[ss-1] + workshort[v[ss]];
+                ++ss;
+                if (ss < setsize)
+                {
+                    gv = GRAPHROW(g,v[ss-1],m);
+                    s1 = (set*)wss + M*(ss-2);
+                    for (i = M; --i >= 0;) s1[i+M] = s1[i] & ~gv[i];
+                    v[ss] = v[ss-1];
+                }
+            }
+        }
+    }
+}
+
+/*****************************************************************************
+*                                                                            *
+*  cliques() assigns to each vertex v a value depending on which cells the   *
+*  vertices which join v in a clique lie in.  The size of the cliques used   *
+*  is the smallest of invararg and MAXCLIQUE.                                *
+*                                                                            *
+*****************************************************************************/
+
+void
+cliques(graph *g, int *lab, int *ptn, int level, int numcells, int tvpos,
+        int *invar, int invararg, boolean digraph, int m, int n)
+{
+    int i;
+    int wt;
+    set *gv;
+    int ss,setsize;
+    int v[MAXCLIQUE];
+    long wv[MAXCLIQUE];
+    set *ns;
+
+#if !MAXN
+    DYNALLOC1(int,workshort,workshort_sz,n+2,"cliques");
+    DYNALLOC2(set,wss,wss_sz,m,MAXCLIQUE-1,"cliques");
+#else
+    set wss[MAXCLIQUE-1][MAXM];
+#endif
+
+    for (i = n; --i >= 0;) invar[i] = 0;
+
+    if (invararg <= 1 || digraph) return;
+
+    if (invararg > MAXCLIQUE) setsize = MAXCLIQUE;
+    else                      setsize = invararg;
+
+    wt = 1;
+    for (i = 0; i < n; ++i)
+    {
+        workshort[lab[i]] = FUZZ2(wt);
+        if (ptn[i] <= level) ++wt;
+    }
+
+    for (v[0] = 0; v[0] < n; ++v[0])
+    {
+        wv[0] = workshort[v[0]];
+        gv = GRAPHROW(g,v[0],m);
+        ns = (set*)wss;
+        for (i = M; --i >= 0;) ns[i] = gv[i];
+        ss = 1;
+        v[1] = v[0];
+        while (ss > 0)
+        {
+            if (ss == setsize)
+            {
+                wt = FUZZ1(wv[ss-1]);
+                for (i = ss; --i >= 0;) ACCUM(invar[v[i]],wt);
+                --ss;
+            }
+            else if ((v[ss] = nextelement((set*)wss+M*(ss-1),M,v[ss])) < 0)
+                --ss;
+            else
+            {
+                wv[ss] = wv[ss-1] + workshort[v[ss]];
+                ++ss;
+                if (ss < setsize)
+                {
+                    gv = GRAPHROW(g,v[ss-1],m);
+                    ns = (set*)wss + M*(ss-2);
+                    for (i = M; --i >= 0;) ns[i+M] = ns[i] & gv[i];
+                    v[ss] = v[ss-1];
+                }
+            }
+        }
+    }
+}
+
+/*****************************************************************************
+*                                                                            *
+*  cellcliq() assigns to each vertex v a value depending on the number of    *
+*  cliques which v lies in and which lie in the same cell as v.  The size    *
+*  of clique counted is the smallest of invararg and MAXCLIQUE.  We try the  *
+*  cells in increasing order of size and stop as soon as any cell splits.    *
+*                                                                            *
+*****************************************************************************/
+
+void
+cellcliq(graph *g, int *lab, int *ptn, int level, int numcells, int tvpos,
+         int *invar, int invararg, boolean digraph, int m, int n)
+{
+    int i;
+    int wt;
+    set *gv;
+    int ss,setsize;
+    int v[MAXCLIQUE];
+    set *ns;
+    int *cellstart,*cellsize;
+    int iv,icell,bigcells,cell1,cell2;
+    int pc;
+    setword sw;
+
+#if !MAXN
+    DYNALLOC1(set,workset,workset_sz,m,"cellcliq");
+    DYNALLOC1(int,workshort,workshort_sz,n+2,"cellcliq");
+    DYNALLOC2(set,wss,wss_sz,m,MAXCLIQUE-1,"cellcliq");
+#endif
+
+    for (i = n; --i >= 0;) invar[i] = 0;
+
+    if (invararg <= 1 || digraph) return;
+
+    if (invararg > MAXCLIQUE) setsize = MAXCLIQUE;
+    else                      setsize = invararg;
+
+    cellstart = workshort;
+    cellsize = workshort + (n/2);
+    getbigcells(ptn,level,setsize > 6 ? setsize : 6,&bigcells,
+                cellstart,cellsize,n);
+
+    for (icell = 0; icell < bigcells; ++icell)
+    {
+        cell1 = cellstart[icell];
+        cell2 = cell1 + cellsize[icell] - 1;
+
+        EMPTYSET(workset,m);
+        for (iv = cell1; iv <= cell2; ++iv) ADDELEMENT(workset,lab[iv]);
+
+        for (iv = cell1; iv <= cell2; ++iv)
+        {
+            v[0] = lab[iv];
+            gv = GRAPHROW(g,v[0],m);
+            ns = (set*)wss;
+            pc = 0;
+
+            for (i = M; --i >= 0;)
+            {
+                ns[i] = gv[i] & workset[i];
+                if ((sw = ns[i]) != 0) pc += POPCOUNT(sw);
+            }
+            if (pc <= 1 || pc >= cellsize[icell] - 2) continue;
+
+            ss = 1;
+            v[1] = v[0];
+            while (ss > 0)
+            {
+                if (ss == setsize)
+                {
+                    for (i = ss; --i >= 0;) ++invar[v[i]];
+                    --ss;
+                }
+                else if ((v[ss] 
+                            = nextelement((set*)wss+M*(ss-1),M,v[ss])) < 0)
+                    --ss;
+                else
+                {
+                    ++ss;
+                    if (ss < setsize)
+                    {
+                        gv = GRAPHROW(g,v[ss-1],m);
+                        ns = (set*)wss + M*(ss-2);
+                        for (i = M; --i >= 0;) ns[i+M] = ns[i] & gv[i];
+                        v[ss] = v[ss-1];
+                    }
+                }
+            }
+        }
+        wt = invar[lab[cell1]];
+        for (iv = cell1 + 1; iv <= cell2; ++iv)
+            if (invar[lab[iv]] != wt) return;
+    }
+}
+
+/*****************************************************************************
+*                                                                            *
+*  cellind() assigns to each vertex v a value depending on the number of     *
+*  independent sets which v lies in and which lie in the same cell as v.     *
+*  The size of clique counted is the smallest of invararg and MAXCLIQUE.     *
+*  We try the cells in increasing order of size and stop as soon as any      *
+*  cell splits.                                                              *
+*                                                                            *
+*****************************************************************************/
+
+void
+cellind(graph *g, int *lab, int *ptn, int level, int numcells, int tvpos,
+        int *invar, int invararg, boolean digraph, int m, int n)
+{
+    int i;
+    int wt;
+    set *gv;
+    int ss,setsize;
+    int v[MAXCLIQUE];
+    set *ns;
+    int *cellstart,*cellsize;
+    int iv,icell,bigcells,cell1,cell2;
+    int pc;
+    setword sw;
+
+#if !MAXN
+    DYNALLOC1(set,workset,workset_sz,m,"cellind");
+    DYNALLOC1(int,workshort,workshort_sz,n+2,"cellind");
+    DYNALLOC2(set,wss,wss_sz,m,MAXCLIQUE-1,"cellind");
+#endif
+
+    for (i = n; --i >= 0;) invar[i] = 0;
+
+    if (invararg <= 1 || digraph) return;
+
+    if (invararg > MAXCLIQUE) setsize = MAXCLIQUE;
+    else                      setsize = invararg;
+
+    cellstart = workshort;
+    cellsize = workshort + (n/2);
+    getbigcells(ptn,level,setsize > 6 ? setsize : 6,&bigcells,
+                cellstart,cellsize,n);
+
+    for (icell = 0; icell < bigcells; ++icell)
+    {
+        cell1 = cellstart[icell];
+        cell2 = cell1 + cellsize[icell] - 1;
+
+        EMPTYSET(workset,m);
+        for (iv = cell1; iv <= cell2; ++iv) ADDELEMENT(workset,lab[iv]);
+
+        for (iv = cell1; iv <= cell2; ++iv)
+        {
+            v[0] = lab[iv];
+            gv = GRAPHROW(g,v[0],m);
+            ns = (set*)wss;
+            pc = 0;
+
+            for (i = M; --i >= 0;)
+            {
+                ns[i] = ~gv[i] & workset[i];
+                if ((sw = ns[i]) != 0) pc += POPCOUNT(sw);
+            }
+            if (pc <= 1 || pc >= cellsize[icell] - 2) continue;
+
+            ss = 1;
+            v[1] = v[0];
+            while (ss > 0)
+            {
+                if (ss == setsize)
+                {
+                    for (i = ss; --i >= 0;) ++invar[v[i]];
+                    --ss;
+                }
+                else if ((v[ss] 
+                       = nextelement((set*)wss+M*(ss-1),M,v[ss])) < 0)
+                    --ss;
+                else
+                {
+                    ++ss;
+                    if (ss < setsize)
+                    {
+                        gv = GRAPHROW(g,v[ss-1],m);
+                        ns = (set*)wss + M*(ss-2);
+                        for (i = M; --i >= 0;) ns[i+M] = ns[i] & ~gv[i];
+                        v[ss] = v[ss-1];
+                    }
+                }
+            }
+        }
+        wt = invar[lab[cell1]];
+        for (iv = cell1 + 1; iv <= cell2; ++iv)
+            if (invar[lab[iv]] != wt) return;
+    }
+}
+
+/*****************************************************************************
+*                                                                            *
+*  adjacencies() assigns to each vertex v a code depending on which cells    *
+*  it is joined to and from, and how many times.  It is intended to provide  *
+*  better partitioning that the normal refinement routine for digraphs.      *
+*  It will not help with undirected graphs in nauty at all.                  *
+*                                                                            *
+*****************************************************************************/
+
+void
+adjacencies(graph *g, int *lab, int *ptn, int level, int numcells, int tvpos,
+            int *invar, int invararg, boolean digraph, int m, int n)
+{
+    int i,v,w;
+    int vwt,wwt;
+    set *gv;
+
+#if !MAXN
+    DYNALLOC1(int,workshort,workshort_sz,n+2,"adjacencies");
+#endif
+
+    vwt = 1;
+    for (i = 0; i < n; ++i)
+    {
+        workshort[lab[i]] = vwt;
+        if (ptn[i] <= level) ++vwt;
+        invar[i] = 0;
+    }
+
+    for (v = 0, gv = (set*)g; v < n; ++v, gv += M)
+    {
+        vwt = FUZZ1(workshort[v]);
+        wwt = 0;
+        w = -1;
+        while ((w = nextelement(gv,M,w)) >= 0)
+        {
+            ACCUM(wwt,FUZZ2(workshort[w]));
+            ACCUM(invar[w],vwt);
+        }
+        ACCUM(invar[v],wwt);
+    }
+}
+
+/*****************************************************************************
+*                                                                            *
+*  nautinv_check() checks that this file is compiled compatibly with the     *
+*  given parameters.   If not, call exit(1).                                 *
+*                                                                            *
+*****************************************************************************/
+
+void
+nautinv_check(int wordsize, int m, int n, int version)
+{
+    if (wordsize != WORDSIZE)
+    {
+        fprintf(ERRFILE,"Error: WORDSIZE mismatch in nautinv.c\n");
+        exit(1);
+    }
+
+#if MAXN
+    if (m > MAXM)
+    {
+        fprintf(ERRFILE,"Error: MAXM inadequate in nautinv.c\n");
+        exit(1);
+    }
+
+    if (n > MAXN)
+    {
+        fprintf(ERRFILE,"Error: MAXN inadequate in nautinv.c\n");
+        exit(1);
+    }
+#endif
+
+    if (version < NAUTYREQUIRED)
+    {
+        fprintf(ERRFILE,"Error: nautinv.c version mismatch\n");
+        exit(1);
+    }
+}
+
+/*****************************************************************************
+*                                                                            *
+*  nautinv_freedyn() - free the dynamic memory in this module                *
+*                                                                            *
+*****************************************************************************/
+ 
+void
+nautinv_freedyn(void)
+{
+#if !MAXN
+    DYNFREE(workset,workset_sz);
+    DYNFREE(workshort,workshort_sz);
+    DYNFREE(ws1,ws1_sz);
+    DYNFREE(ws2,ws2_sz);
+    DYNFREE(vv,vv_sz);
+    DYNFREE(ww,ww_sz);
+    DYNFREE(w01,w01_sz);
+    DYNFREE(w02,w02_sz);
+    DYNFREE(w03,w03_sz);
+    DYNFREE(w12,w12_sz);
+    DYNFREE(w13,w13_sz);
+    DYNFREE(w23,w23_sz);
+    DYNFREE(pt0,pt0_sz);
+    DYNFREE(pt1,pt1_sz);
+    DYNFREE(pt2,pt2_sz);
+    DYNFREE(wss,wss_sz);
+#endif
+}
+
+/*===================================================================*/
+
+
+/*****************************************************************************
+*                                                                            *
+*  semirefine(g,lab,ptn,level,numcells,strength,active,m,n) performs a       *
+*  refinement operation on the partition at the specified level of the       *
+*  partition nest (lab,ptn).  *numcells is assumed to contain the number of  *
+*  cells on input, and is updated.  The initial set of active cells (alpha   *
+*  in the paper) is specified in the set active.  Precisely, x is in active  *
+*  iff the cell starting at index x in lab is active.                        *
+*  *code is set to a value which depends on the fine detail of the           *
+*  algorithm, but which is independent of the labelling of the graph.        *
+*                                                                            *
+*****************************************************************************/
+
+static int
+semirefine(graph *g, int *lab, int *ptn, int level, int *numcells,
+           int strength, set *active, int m, int n)
+{
+    int i,c1,c2,labc1;
+    setword x;
+    set *set1,*set2;
+    int split1,split2,cell1,cell2;
+    int cnt,bmin,bmax;
+    long longcode;
+    set *gptr;
+    int maxcell,maxpos,hint;
+
+#if !MAXN
+    DYNALLOC1(int,workperm,workperm_sz,n,"refine");
+    DYNALLOC1(set,workset,workset_sz,m,"refine");
+    DYNALLOC1(int,bucket,bucket_sz,n+2,"refine");
+    DYNALLOC1(int,count,count_sz,n,"refine");
+#endif
+
+    longcode = *numcells;
+    split1 = -1;
+    hint = 0;
+    while (*numcells < n && ((split1 = hint, ISELEMENT(active,split1))
+                         || (split1 = nextelement(active,M,split1)) >= 0
+                         || (split1 = nextelement(active,M,-1)) >= 0))
+    {
+        DELELEMENT(active,split1);
+        for (split2 = split1; ptn[split2] > level; ++split2) {}
+        longcode = MASH(longcode,split1+split2);
+        if (split1 == split2)       /* trivial splitting cell */
+        {
+            gptr = GRAPHROW(g,lab[split1],M);
+            for (cell1 = 0; cell1 < n; cell1 = cell2 + 1)
+            {
+                for (cell2 = cell1; ptn[cell2] > level; ++cell2) {}
+                if (cell1 == cell2) continue;
+                c1 = cell1;
+                c2 = cell2;
+                while (c1 <= c2)
+                {
+                    labc1 = lab[c1];
+                    if (ISELEMENT(gptr,labc1))
+                        ++c1;
+                    else
+                    {
+                        lab[c1] = lab[c2];
+                        lab[c2] = labc1;
+                        --c2;
+                    }
+                }
+                if (c2 >= cell1 && c1 <= cell2)
+                {
+                    ptn[c2] = level;
+                    longcode = MASH(longcode,FUZZ1(c2));
+                    ++*numcells;
+                    if (ISELEMENT(active,cell1) || c2-cell1 >= cell2-c1)
+                    {
+                        ADDELEMENT(active,c1);
+                        if (c1 == cell2) hint = c1;
+                    }
+                    else
+                    {
+                        ADDELEMENT(active,cell1);
+                        if (c2 == cell1) hint = cell1;
+                    }
+                }
+            }
+        }
+        else        /* nontrivial splitting cell */
+        {
+            EMPTYSET(workset,m);
+            for (i = split1; i <= split2; ++i)
+                ADDELEMENT(workset,lab[i]);
+            longcode = MASH(longcode,FUZZ2(split2-split1+1));
+
+            for (cell1 = 0; cell1 < n; cell1 = cell2 + 1)
+            {
+                for (cell2 = cell1; ptn[cell2] > level; ++cell2) {}
+                if (cell1 == cell2) continue;
+                i = cell1;
+                set1 = workset;
+                set2 = GRAPHROW(g,lab[i],m);
+                cnt = 0;
+                for (c1 = m; --c1 >= 0;)
+                    if ((x = ((*set1++) & (*set2++))) != 0)
+                        cnt += POPCOUNT(x);
+
+                count[i] = bmin = bmax = cnt;
+                bucket[cnt] = 1;
+                while (++i <= cell2)
+                {
+                    set1 = workset;
+                    set2 = GRAPHROW(g,lab[i],m);
+                    cnt = 0;
+                    for (c1 = m; --c1 >= 0;)
+                        if ((x = ((*set1++) & (*set2++))) != 0)
+                            cnt += POPCOUNT(x);
+
+                    while (bmin > cnt) bucket[--bmin] = 0;
+                    while (bmax < cnt) bucket[++bmax] = 0;
+                    ++bucket[cnt];
+                    count[i] = cnt;
+                }
+                if (bmin == bmax)
+                {
+                    longcode = MASH(longcode,FUZZ1(bmin+cell1));
+                    continue;
+                }
+                c1 = cell1;
+                maxcell = -1;
+                for (i = bmin; i <= bmax; ++i)
+                    if (bucket[i])
+                    {
+                        c2 = c1 + bucket[i];
+                        bucket[i] = c1;
+                        longcode = MASH(longcode,i+c1);
+                        if (c2-c1 > maxcell)
+                        {
+                            maxcell = c2-c1;
+                            maxpos = c1;
+                        }
+                        if (c1 != cell1)
+                        {
+                            ADDELEMENT(active,c1);
+                            if (c2-c1 == 1) hint = c1;
+                            ++*numcells;
+                        }
+                        if (c2 <= cell2) ptn[c2-1] = level;
+                        c1 = c2;
+                    }
+                for (i = cell1; i <= cell2; ++i)
+                    workperm[bucket[count[i]]++] = lab[i];
+                for (i = cell1; i <= cell2; ++i) lab[i] = workperm[i];
+                if (!ISELEMENT(active,cell1))
+                {
+                    ADDELEMENT(active,cell1);
+                    DELELEMENT(active,maxpos);     /* check maxpos is alwas defined */
+                }
+            }
+        }
+        if (--strength == 0) break;   /* negative is fine! */
+    }
+
+    longcode = MASH(longcode,FUZZ2(*numcells));
+    return CLEANUP(longcode);
+}
+
+void 
+refinvar(graph *g, int *lab, int *ptn, int level, int numcells, int tvpos,
+          int *invar, int invararg, boolean digraph, int m, int n)
+{
+    int i,j;
+    int wt;
+    int icell,bigcells,cell1,cell2;
+    int *cellstart,*cellsize;
+    int newnumcells;
+
+#if !MAXN
+    DYNALLOC1(int,workshort,workshort_sz,n+2,"refinvar");
+    DYNALLOC1(int,vv,vv_sz,n,"refinvar");
+    DYNALLOC1(int,ww,ww_sz,n,"refinvar");
+    DYNALLOC1(set,ws1,ws1_sz,n,"refinvar");
+#endif
+
+    for (i = n; --i >= 0;) invar[i] = 0;
+
+    cellstart = workshort;
+    cellsize = workshort + (n/2);
+    getbigcells(ptn,level,2,&bigcells,cellstart,cellsize,n);
+
+    for (icell = 0; icell < bigcells; ++icell)
+    {
+        cell1 = cellstart[icell];
+        cell2 = cell1 + cellsize[icell] - 1;
+        for (i = cell1; i <= cell2; ++i)
+        {
+            for (j = 0; j < n; ++j)
+            {
+                vv[j] = lab[j];
+                ww[j] = ptn[j];
+            }
+            newnumcells = numcells + 1;
+            ww[cell1] = level;
+            EMPTYSET(ws1,m);
+            ADDELEMENT(ws1,cell1);
+            vv[i] = lab[cell1];
+            vv[cell1] = lab[i];
+            invar[lab[i]] = semirefine(g,vv,ww,level,&newnumcells,
+                                            invararg,ws1,m,n);
+        }
+        wt = invar[lab[cell1]];
+        for (i = cell1 + 1; i <= cell2; ++i)
+            if (invar[lab[i]] != wt) return;
+    }
+}