int igraph_is_separator(const igraph_t *graph, 
			const igraph_vs_t candidate,
			igraph_bool_t *res) {

  long int no_of_nodes=igraph_vcount(graph);
  igraph_vector_bool_t removed;
  igraph_dqueue_t Q;
  igraph_vector_t neis;
  igraph_vit_t vit;

  IGRAPH_CHECK(igraph_vit_create(graph, candidate, &vit));
  IGRAPH_FINALLY(igraph_vit_destroy, &vit);
  IGRAPH_CHECK(igraph_vector_bool_init(&removed, no_of_nodes));
  IGRAPH_FINALLY(igraph_vector_bool_destroy, &removed);
  IGRAPH_CHECK(igraph_dqueue_init(&Q, 100));
  IGRAPH_FINALLY(igraph_dqueue_destroy, &Q);
  IGRAPH_VECTOR_INIT_FINALLY(&neis, 0);

  IGRAPH_CHECK(igraph_i_is_separator(graph, &vit, -1, res, &removed, 
				     &Q, &neis, no_of_nodes));

  igraph_vector_destroy(&neis);
  igraph_dqueue_destroy(&Q);
  igraph_vector_bool_destroy(&removed);
  igraph_vit_destroy(&vit);
  IGRAPH_FINALLY_CLEAN(4);

  return 0;
}

int igraph_i_largest_weighted_cliques(const igraph_t *graph,
                    const igraph_vector_t *vertex_weights, igraph_vector_ptr_t *res)
{
    graph_t *g;
    igraph_integer_t vcount = igraph_vcount(graph);

    if (vcount == 0) {
        igraph_vector_ptr_clear(res);
        return IGRAPH_SUCCESS;
    }

    igraph_to_cliquer(graph, &g);
    IGRAPH_FINALLY(graph_free, g);

    IGRAPH_CHECK(set_weights(vertex_weights, g));

    igraph_vector_ptr_clear(res);
    igraph_cliquer_opt.user_data = res;
    igraph_cliquer_opt.user_function = &collect_cliques_callback;

    IGRAPH_FINALLY(free_clique_list, res);
    CLIQUER_INTERRUPTABLE(clique_find_all(g, 0, 0, FALSE, &igraph_cliquer_opt));
    IGRAPH_FINALLY_CLEAN(1);

    graph_free(g);
    IGRAPH_FINALLY_CLEAN(1);

    return IGRAPH_SUCCESS;
}

int igraph_i_cliquer_cliques(const igraph_t *graph, igraph_vector_ptr_t *res,
                    igraph_integer_t min_size, igraph_integer_t max_size)
{
    graph_t *g;
    igraph_integer_t vcount = igraph_vcount(graph);

    if (vcount == 0) {
        igraph_vector_ptr_clear(res);
        return IGRAPH_SUCCESS;
    }

    if (min_size <= 0) min_size = 1;
    if (max_size <= 0) max_size = 0;

    if (max_size > 0 && max_size < min_size)
        IGRAPH_ERROR("max_size must not be smaller than min_size", IGRAPH_EINVAL);

    igraph_to_cliquer(graph, &g);
    IGRAPH_FINALLY(graph_free, g);

    igraph_vector_ptr_clear(res);
    igraph_cliquer_opt.user_data = res;
    igraph_cliquer_opt.user_function = &collect_cliques_callback;

    IGRAPH_FINALLY(free_clique_list, res);
    CLIQUER_INTERRUPTABLE(clique_unweighted_find_all(g, min_size, max_size, /* maximal= */ FALSE, &igraph_cliquer_opt));
    IGRAPH_FINALLY_CLEAN(1);

    graph_free(g);
    IGRAPH_FINALLY_CLEAN(1);

    return IGRAPH_SUCCESS;
}

int igraph_i_local_scan_1_directed(const igraph_t *graph,
				   igraph_vector_t *res,
				   const igraph_vector_t *weights,
				   igraph_neimode_t mode) {

  int no_of_nodes=igraph_vcount(graph);
  igraph_inclist_t incs;
  int i, node;

  igraph_vector_int_t neis;

  IGRAPH_CHECK(igraph_inclist_init(graph, &incs, mode));
  IGRAPH_FINALLY(igraph_inclist_destroy, &incs);

  igraph_vector_int_init(&neis, no_of_nodes);
  IGRAPH_FINALLY(igraph_vector_int_destroy, &neis);

  igraph_vector_resize(res, no_of_nodes);
  igraph_vector_null(res);

  for (node=0; node < no_of_nodes; node++) {
    igraph_vector_int_t *edges1=igraph_inclist_get(&incs, node);
    int edgeslen1=igraph_vector_int_size(edges1);

    IGRAPH_ALLOW_INTERRUPTION();

    /* Mark neighbors and self*/
    VECTOR(neis)[node] = node+1;
    for (i=0; i<edgeslen1; i++) {
      int e=VECTOR(*edges1)[i];
      int nei=IGRAPH_OTHER(graph, e, node);
      igraph_real_t w= weights ? VECTOR(*weights)[e] : 1;
      VECTOR(neis)[nei] = node+1;
      VECTOR(*res)[node] += w;
    }

    /* Crawl neighbors */
    for (i=0; i<edgeslen1; i++) {
      int e2=VECTOR(*edges1)[i];
      int nei=IGRAPH_OTHER(graph, e2, node);
      igraph_vector_int_t *edges2=igraph_inclist_get(&incs, nei);
      int j, edgeslen2=igraph_vector_int_size(edges2);
      for (j=0; j<edgeslen2; j++) {
	int e2=VECTOR(*edges2)[j];
	int nei2=IGRAPH_OTHER(graph, e2, nei);
	igraph_real_t w2= weights ? VECTOR(*weights)[e2] : 1;
	if (VECTOR(neis)[nei2] == node+1) {
	  VECTOR(*res)[node] += w2;
	}
      }
    }

  } /* node < no_of_nodes */

  igraph_vector_int_destroy(&neis);
  igraph_inclist_destroy(&incs);
  IGRAPH_FINALLY_CLEAN(2);

  return 0;
}

int igraph_adjlist_init_complementer(const igraph_t *graph,
				       igraph_adjlist_t *al, 
				       igraph_neimode_t mode,
				       igraph_bool_t loops) {
  long int i, j, k, n;
  igraph_bool_t* seen;
  igraph_vector_t vec;

  if (mode != IGRAPH_IN && mode != IGRAPH_OUT && mode != IGRAPH_ALL) {
    IGRAPH_ERROR("Cannot create complementer adjlist view", IGRAPH_EINVMODE);
  }

  if (!igraph_is_directed(graph)) { mode=IGRAPH_ALL; }

  al->length=igraph_vcount(graph);
  al->adjs=igraph_Calloc(al->length, igraph_vector_t);
  if (al->adjs == 0) {
    IGRAPH_ERROR("Cannot create complementer adjlist view", IGRAPH_ENOMEM);
  }

  IGRAPH_FINALLY(igraph_adjlist_destroy, al);

  n=al->length;
  seen=igraph_Calloc(n, igraph_bool_t);
  if (seen==0) {
    IGRAPH_ERROR("Cannot create complementer adjlist view", IGRAPH_ENOMEM);
  }
  IGRAPH_FINALLY(igraph_free, seen);

  IGRAPH_VECTOR_INIT_FINALLY(&vec, 0);

  for (i=0; i<al->length; i++) {
    IGRAPH_ALLOW_INTERRUPTION();
    igraph_neighbors(graph, &vec, i, mode);
    memset(seen, 0, sizeof(igraph_bool_t)*al->length);
    n=al->length;
    if (!loops) { seen[i] = 1; n--; }
    for (j=0; j<igraph_vector_size(&vec); j++) {
      if (! seen [ (long int) VECTOR(vec)[j] ] ) {
	n--;
	seen[ (long int) VECTOR(vec)[j] ] = 1;
      }
    }
    IGRAPH_CHECK(igraph_vector_init(&al->adjs[i], n));
    for (j=0, k=0; k<n; j++) {
      if (!seen[j]) {
	VECTOR(al->adjs[i])[k++] = j;
      }
    }
  }

  igraph_Free(seen);
  igraph_vector_destroy(&vec);
  IGRAPH_FINALLY_CLEAN(3);
  return 0;
}

int igraph_i_separators_store(igraph_vector_ptr_t *separators, 
			      const igraph_adjlist_t *adjlist,
			      igraph_vector_t *components, 
			      igraph_vector_t *leaveout, 
			      unsigned long int *mark, 
			      igraph_vector_t *sorter) {
  
  /* We need to stote N(C), the neighborhood of C, but only if it is 
   * not already stored among the separators.
   */
  
  long int cptr=0, next, complen=igraph_vector_size(components);

  while (cptr < complen) {
    long int saved=cptr;
    igraph_vector_clear(sorter);

    /* Calculate N(C) for the next C */

    while ( (next=(long int) VECTOR(*components)[cptr++]) != -1) {
      VECTOR(*leaveout)[next] = *mark;
    }
    cptr=saved;

    while ( (next=(long int) VECTOR(*components)[cptr++]) != -1) {
      igraph_vector_int_t *neis=igraph_adjlist_get(adjlist, next);
      long int j, nn=igraph_vector_int_size(neis);
      for (j=0; j<nn; j++) {
	long int nei=(long int) VECTOR(*neis)[j];
	if (VECTOR(*leaveout)[nei] != *mark) {
	  igraph_vector_push_back(sorter, nei);
	  VECTOR(*leaveout)[nei] = *mark;
	}
      }    
    }
    igraph_vector_sort(sorter);

    UPDATEMARK();

    /* Add it to the list of separators, if it is new */

    if (igraph_i_separators_newsep(separators, sorter)) {
      igraph_vector_t *newc=igraph_Calloc(1, igraph_vector_t);
      if (!newc) {
	IGRAPH_ERROR("Cannot calculate minimal separators", IGRAPH_ENOMEM);
      }
      IGRAPH_FINALLY(igraph_free, newc);
      igraph_vector_copy(newc, sorter);
      IGRAPH_FINALLY(igraph_vector_destroy, newc);
      IGRAPH_CHECK(igraph_vector_ptr_push_back(separators, newc));
      IGRAPH_FINALLY_CLEAN(2);      
    }
  } /* while cptr < complen */

  return 0;
}

int igraph_i_maximal_or_largest_cliques_or_indsets(const igraph_t *graph,
                                        igraph_vector_ptr_t *res,
                                        igraph_integer_t *clique_number,
                                        igraph_bool_t keep_only_largest,
                                        igraph_bool_t complementer) {
  igraph_i_max_ind_vsets_data_t clqdata;
  long int no_of_nodes = igraph_vcount(graph), i;

  if (igraph_is_directed(graph))
    IGRAPH_WARNING("directionality of edges is ignored for directed graphs");

  clqdata.matrix_size=no_of_nodes;
  clqdata.keep_only_largest=keep_only_largest;

  if (complementer)
    IGRAPH_CHECK(igraph_adjlist_init_complementer(graph, &clqdata.adj_list, IGRAPH_ALL, 0));
  else
    IGRAPH_CHECK(igraph_adjlist_init(graph, &clqdata.adj_list, IGRAPH_ALL));
  IGRAPH_FINALLY(igraph_adjlist_destroy, &clqdata.adj_list);

  clqdata.IS = igraph_Calloc(no_of_nodes, igraph_integer_t);
  if (clqdata.IS == 0)
    IGRAPH_ERROR("igraph_i_maximal_or_largest_cliques_or_indsets failed", IGRAPH_ENOMEM);
  IGRAPH_FINALLY(igraph_free, clqdata.IS);

  IGRAPH_VECTOR_INIT_FINALLY(&clqdata.deg, no_of_nodes);
  for (i=0; i<no_of_nodes; i++)
    VECTOR(clqdata.deg)[i] = igraph_vector_size(igraph_adjlist_get(&clqdata.adj_list, i));

  clqdata.buckets = igraph_Calloc(no_of_nodes+1, igraph_set_t);
  if (clqdata.buckets == 0)
    IGRAPH_ERROR("igraph_maximal_or_largest_cliques_or_indsets failed", IGRAPH_ENOMEM);
  IGRAPH_FINALLY(igraph_i_free_set_array, clqdata.buckets);

  for (i=0; i<no_of_nodes; i++)
    IGRAPH_CHECK(igraph_set_init(&clqdata.buckets[i], 0));

  if (res) igraph_vector_ptr_clear(res);
  
  /* Do the show */
  clqdata.largest_set_size=0;
  IGRAPH_CHECK(igraph_i_maximal_independent_vertex_sets_backtrack(graph, res, &clqdata, 0));

  /* Cleanup */
  for (i=0; i<no_of_nodes; i++) igraph_set_destroy(&clqdata.buckets[i]);
  igraph_adjlist_destroy(&clqdata.adj_list);
  igraph_vector_destroy(&clqdata.deg);
  igraph_free(clqdata.IS);
  igraph_free(clqdata.buckets);
  IGRAPH_FINALLY_CLEAN(4);

  if (clique_number) *clique_number = clqdata.largest_set_size;
  return 0;
}

/**
 * \ingroup structural
 * \function igraph_similarity_jaccard
 * \brief Jaccard similarity coefficient for the given vertices.
 *
 * </para><para>
 * The Jaccard similarity coefficient of two vertices is the number of common
 * neighbors divided by the number of vertices that are neighbors of at
 * least one of the two vertices being considered. This function calculates
 * the pairwise Jaccard similarities for some (or all) of the vertices.
 *
 * \param graph The graph object to analyze
 * \param res Pointer to a matrix, the result of the calculation will
 *        be stored here. The number of its rows and columns is the same
 *        as the number of vertex ids in \p vids.
 * \param vids The vertex ids of the vertices for which the
 *        calculation will be done.
 * \param mode The type of neighbors to be used for the calculation in
 *        directed graphs. Possible values:
 *        \clist
 *        \cli IGRAPH_OUT
 *          the outgoing edges will be considered for each node.
 *        \cli IGRAPH_IN
 *          the incoming edges will be considered for each node.
 *        \cli IGRAPH_ALL
 *          the directed graph is considered as an undirected one for the
 *          computation.
 *        \endclist
 * \param loops Whether to include the vertices themselves in the neighbor
 *        sets.
 * \return Error code:
 *        \clist
 *        \cli IGRAPH_ENOMEM
 *           not enough memory for temporary data.
 *        \cli IGRAPH_EINVVID
 *           invalid vertex id passed.
 *        \cli IGRAPH_EINVMODE
 *           invalid mode argument.
 *        \endclist
 * 
 * Time complexity: O(|V|^2 d),
 * |V| is the number of vertices in the vertex iterator given, d is the
 * (maximum) degree of the vertices in the graph.
 *
 * \sa \ref igraph_similarity_dice(), a measure very similar to the Jaccard
 *   coefficient
 * 
 * \example examples/simple/igraph_similarity.c
 */
int igraph_similarity_jaccard(const igraph_t *graph, igraph_matrix_t *res,
    const igraph_vs_t vids, igraph_neimode_t mode, igraph_bool_t loops) {
  igraph_lazy_adjlist_t al;
  igraph_vit_t vit, vit2;
  long int i, j, k;
  long int len_union, len_intersection;
  igraph_vector_t *v1, *v2;

  IGRAPH_CHECK(igraph_vit_create(graph, vids, &vit));
  IGRAPH_FINALLY(igraph_vit_destroy, &vit);
  IGRAPH_CHECK(igraph_vit_create(graph, vids, &vit2));
  IGRAPH_FINALLY(igraph_vit_destroy, &vit2);

  IGRAPH_CHECK(igraph_lazy_adjlist_init(graph, &al, mode, IGRAPH_SIMPLIFY));
  IGRAPH_FINALLY(igraph_lazy_adjlist_destroy, &al);

  IGRAPH_CHECK(igraph_matrix_resize(res, IGRAPH_VIT_SIZE(vit), IGRAPH_VIT_SIZE(vit)));

  if (loops) {
    for (IGRAPH_VIT_RESET(vit); !IGRAPH_VIT_END(vit); IGRAPH_VIT_NEXT(vit)) {
      i=IGRAPH_VIT_GET(vit);
      v1=igraph_lazy_adjlist_get(&al, (igraph_integer_t) i);
      if (!igraph_vector_binsearch(v1, i, &k))
        igraph_vector_insert(v1, k, i);
    }
  }

  for (IGRAPH_VIT_RESET(vit), i=0;
    !IGRAPH_VIT_END(vit); IGRAPH_VIT_NEXT(vit), i++) {
    MATRIX(*res, i, i) = 1.0;
    for (IGRAPH_VIT_RESET(vit2), j=0;
      !IGRAPH_VIT_END(vit2); IGRAPH_VIT_NEXT(vit2), j++) {
      if (j <= i)
        continue;
      v1=igraph_lazy_adjlist_get(&al, IGRAPH_VIT_GET(vit));
      v2=igraph_lazy_adjlist_get(&al, IGRAPH_VIT_GET(vit2));
      igraph_i_neisets_intersect(v1, v2, &len_union, &len_intersection);
      if (len_union > 0)
        MATRIX(*res, i, j) = ((igraph_real_t)len_intersection)/len_union;
      else
        MATRIX(*res, i, j) = 0.0;
      MATRIX(*res, j, i) = MATRIX(*res, i, j);
    }
  }

  igraph_lazy_adjlist_destroy(&al);
  igraph_vit_destroy(&vit);
  igraph_vit_destroy(&vit2);
  IGRAPH_FINALLY_CLEAN(3);

  return 0;
//.........这里部分代码省略.........

int igraph_is_minimal_separator(const igraph_t *graph,
				const igraph_vs_t candidate, 
				igraph_bool_t *res) {

  long int no_of_nodes=igraph_vcount(graph);
  igraph_vector_bool_t removed;
  igraph_dqueue_t Q;
  igraph_vector_t neis;
  long int candsize;
  igraph_vit_t vit;
  
  IGRAPH_CHECK(igraph_vit_create(graph, candidate, &vit));
  IGRAPH_FINALLY(igraph_vit_destroy, &vit);
  candsize=IGRAPH_VIT_SIZE(vit);

  IGRAPH_CHECK(igraph_vector_bool_init(&removed, no_of_nodes));
  IGRAPH_FINALLY(igraph_vector_bool_destroy, &removed);
  IGRAPH_CHECK(igraph_dqueue_init(&Q, 100));
  IGRAPH_FINALLY(igraph_dqueue_destroy, &Q);
  IGRAPH_VECTOR_INIT_FINALLY(&neis, 0);

  /* Is it a separator at all? */
  IGRAPH_CHECK(igraph_i_is_separator(graph, &vit, -1, res, &removed, 
				     &Q, &neis, no_of_nodes));
  if (!(*res)) {
    /* Not a separator at all, nothing to do, *res is already set */
  } else if (candsize == 0) {
    /* Nothing to do, minimal, *res is already set */
  } else {
    /* General case, we need to remove each vertex from 'candidate'
     * and check whether the remainder is a separator. If this is
     * false for all vertices, then 'candidate' is a minimal
     * separator.
     */
    long int i;
    for (i=0, *res=0; i<candsize && (!*res); i++) {
      igraph_vector_bool_null(&removed);
      IGRAPH_CHECK(igraph_i_is_separator(graph, &vit, i, res, &removed, 
					 &Q, &neis, no_of_nodes));    
    }
    (*res) = (*res) ? 0 : 1;	/* opposite */
  }
  
  igraph_vector_destroy(&neis);
  igraph_dqueue_destroy(&Q);
  igraph_vector_bool_destroy(&removed);
  igraph_vit_destroy(&vit);
  IGRAPH_FINALLY_CLEAN(4);

  return 0;
}

/* call-seq:
 *   graph.constraint(vs,weights) -> Array
 *
 * Returns an Array of constraint measures for the vertices 
 * in the graph. Weights is an Array of weight measures for each edge.
 */
VALUE cIGraph_constraint(int argc, VALUE *argv, VALUE self){

  igraph_t *graph;
  igraph_vs_t vids;
  igraph_vector_t vidv;
  igraph_vector_t res;
  igraph_vector_t wght;
  int i;
  VALUE constraints = rb_ary_new();
  VALUE vs, weights;

  rb_scan_args(argc,argv,"11",&vs, &weights);

  //vector to hold the results of the degree calculations
  IGRAPH_FINALLY(igraph_vector_destroy, &res);
  IGRAPH_FINALLY(igraph_vector_destroy, &wght);
  IGRAPH_FINALLY(igraph_vector_destroy, &vidv);
  IGRAPH_CHECK(igraph_vector_init(&res,0));
  IGRAPH_CHECK(igraph_vector_init(&wght,0));

  Data_Get_Struct(self, igraph_t, graph);

  //Convert an array of vertices to a vector of vertex ids
  IGRAPH_CHECK(igraph_vector_init_int(&vidv,0));
  cIGraph_vertex_arr_to_id_vec(self,vs,&vidv);
  //create vertex selector from the vecotr of ids
  igraph_vs_vector(&vids,&vidv);

  if(weights == Qnil){
    IGRAPH_CHECK(igraph_constraint(graph,&res,vids,NULL));
  } else {
    for(i=0;i<RARRAY_LEN(weights);i++){
      IGRAPH_CHECK(igraph_vector_push_back(&wght,NUM2DBL(RARRAY_PTR(weights)[i])));
    }
    IGRAPH_CHECK(igraph_constraint(graph,&res,vids,&wght));
  }

  for(i=0;i<igraph_vector_size(&res);i++){
    rb_ary_push(constraints,rb_float_new(VECTOR(res)[i]));
  }

  igraph_vector_destroy(&vidv);
  igraph_vector_destroy(&res);
  igraph_vector_destroy(&wght);
  igraph_vs_destroy(&vids);

  IGRAPH_FINALLY_CLEAN(3);

  return constraints;

}

int igraph_get_edgelist(const igraph_t *graph, igraph_vector_t *res, igraph_bool_t bycol) {

  igraph_eit_t edgeit;
  long int no_of_edges=igraph_ecount(graph);
  long int vptr=0;
  igraph_integer_t from, to;
  
  IGRAPH_CHECK(igraph_vector_resize(res, no_of_edges*2));
  IGRAPH_CHECK(igraph_eit_create(graph, igraph_ess_all(IGRAPH_EDGEORDER_ID),
				 &edgeit));
  IGRAPH_FINALLY(igraph_eit_destroy, &edgeit);
  
  if (bycol) {
    while (!IGRAPH_EIT_END(edgeit)) {
      igraph_edge(graph, IGRAPH_EIT_GET(edgeit), &from, &to);
      VECTOR(*res)[vptr]=from;
      VECTOR(*res)[vptr+no_of_edges]=to;
      vptr++;
      IGRAPH_EIT_NEXT(edgeit);
    }
  } else {
    while (!IGRAPH_EIT_END(edgeit)) {
      igraph_edge(graph, IGRAPH_EIT_GET(edgeit), &from, &to);
      VECTOR(*res)[vptr++]=from;
      VECTOR(*res)[vptr++]=to;
      IGRAPH_EIT_NEXT(edgeit);
    }
  }
  
  igraph_eit_destroy(&edgeit);
  IGRAPH_FINALLY_CLEAN(1);
  return 0;
}

int igraph_i_weighted_clique_number(const igraph_t *graph,
                    const igraph_vector_t *vertex_weights, igraph_real_t *res)
{
    graph_t *g;
    igraph_integer_t vcount = igraph_vcount(graph);

    if (vcount == 0) {
        *res = 0;
        return IGRAPH_SUCCESS;
    }

    igraph_to_cliquer(graph, &g);
    IGRAPH_FINALLY(graph_free, g);

    IGRAPH_CHECK(set_weights(vertex_weights, g));

    igraph_cliquer_opt.user_function = NULL;

    /* we are not using a callback function, thus this is not interruptable */
    *res = clique_max_weight(g, &igraph_cliquer_opt);

    graph_free(g);
    IGRAPH_FINALLY_CLEAN(1);

    return IGRAPH_SUCCESS;
}

int igraph_i_cliquer_callback(const igraph_t *graph,
                    igraph_integer_t min_size, igraph_integer_t max_size,
                    igraph_clique_handler_t *cliquehandler_fn, void *arg)
{
    graph_t *g;
    struct callback_data cd;
    igraph_integer_t vcount = igraph_vcount(graph);

    if (vcount == 0)
        return IGRAPH_SUCCESS;

    if (min_size <= 0) min_size = 1;
    if (max_size <= 0) max_size = 0;

    if (max_size > 0 && max_size < min_size)
        IGRAPH_ERROR("max_size must not be smaller than min_size", IGRAPH_EINVAL);

    igraph_to_cliquer(graph, &g);
    IGRAPH_FINALLY(graph_free, g);

    cd.handler = cliquehandler_fn;
    cd.arg = arg;
    igraph_cliquer_opt.user_data = &cd;
    igraph_cliquer_opt.user_function = &callback_callback;

    CLIQUER_INTERRUPTABLE(clique_unweighted_find_all(g, min_size, max_size, /* maximal= */ FALSE, &igraph_cliquer_opt));

    graph_free(g);
    IGRAPH_FINALLY_CLEAN(1);

    return IGRAPH_SUCCESS;
}

int igraph_inclist_init(const igraph_t *graph, 
			      igraph_inclist_t *il, 
			      igraph_neimode_t mode) {
  long int i;

  if (mode != IGRAPH_IN && mode != IGRAPH_OUT && mode != IGRAPH_ALL) {
    IGRAPH_ERROR("Cannot create incidence list view", IGRAPH_EINVMODE);
  }

  if (!igraph_is_directed(graph)) { mode=IGRAPH_ALL; }

  il->length=igraph_vcount(graph);
  il->incs=igraph_Calloc(il->length, igraph_vector_t);
  if (il->incs == 0) {
    IGRAPH_ERROR("Cannot create incidence list view", IGRAPH_ENOMEM);
  }

  IGRAPH_FINALLY(igraph_inclist_destroy, il);  
  for (i=0; i<il->length; i++) {
    IGRAPH_ALLOW_INTERRUPTION();
    IGRAPH_CHECK(igraph_vector_init(&il->incs[i], 0));
    IGRAPH_CHECK(igraph_incident(graph, &il->incs[i], i, mode));
  }
  
  IGRAPH_FINALLY_CLEAN(1);
  return 0;
}

int igraph_i_trans4_il_simplify(const igraph_t *graph, igraph_inclist_t *il,
				const igraph_vector_int_t *rank) {

  long int i;
  long int n=il->length;
  igraph_vector_int_t mark;
  igraph_vector_int_init(&mark, n);
  IGRAPH_FINALLY(igraph_vector_int_destroy, &mark);

  for (i=0; i<n; i++) {
    igraph_vector_int_t *v=&il->incs[i];
    int j, l=igraph_vector_int_size(v);
    int irank=VECTOR(*rank)[i];
    VECTOR(mark)[i] = i+1;
    for (j=0; j<l; /* nothing */) {
      long int edge=(long int) VECTOR(*v)[j];
      long int e=IGRAPH_OTHER(graph, edge, i);
      if (VECTOR(*rank)[e] > irank && VECTOR(mark)[e] != i+1) {
	VECTOR(mark)[e]=i+1;
	j++;
      } else {
	VECTOR(*v)[j] = igraph_vector_int_tail(v);
	igraph_vector_int_pop_back(v);
	l--;
      }
    }
  }

  igraph_vector_int_destroy(&mark);
  IGRAPH_FINALLY_CLEAN(1);
  return 0;

}

int igraph_local_scan_0_them(const igraph_t *us, const igraph_t *them,
			     igraph_vector_t *res,
			     const igraph_vector_t *weights_them,
			     igraph_neimode_t mode) {

  igraph_t is;

  if (igraph_vcount(us) != igraph_vcount(them)) {
    IGRAPH_ERROR("Number of vertices don't match in scan-0", IGRAPH_EINVAL);
  }
  if (igraph_is_directed(us) != igraph_is_directed(them)) {
    IGRAPH_ERROR("Directedness don't match in scan-0", IGRAPH_EINVAL);
  }

  if (weights_them) {
    return igraph_i_local_scan_0_them_w(us, them, res, weights_them, mode);
  }

  igraph_intersection(&is, us, them, /*edgemap1=*/ 0, /*edgemap2=*/ 0);
  IGRAPH_FINALLY(igraph_destroy, &is);

  igraph_degree(&is, res, igraph_vss_all(), mode, IGRAPH_LOOPS);

  igraph_destroy(&is);
  IGRAPH_FINALLY_CLEAN(1);

  return 0;
}

int igraph_adjlist_init(const igraph_t *graph, igraph_adjlist_t *al, 
			  igraph_neimode_t mode) {
  long int i;

  if (mode != IGRAPH_IN && mode != IGRAPH_OUT && mode != IGRAPH_ALL) {
    IGRAPH_ERROR("Cannot create adjlist view", IGRAPH_EINVMODE);
  }

  if (!igraph_is_directed(graph)) { mode=IGRAPH_ALL; }

  al->length=igraph_vcount(graph);
  al->adjs=igraph_Calloc(al->length, igraph_vector_t);
  if (al->adjs == 0) {
    IGRAPH_ERROR("Cannot create adjlist view", IGRAPH_ENOMEM);
  }

  IGRAPH_FINALLY(igraph_adjlist_destroy, al);
  for (i=0; i<al->length; i++) {
    IGRAPH_ALLOW_INTERRUPTION();
    IGRAPH_CHECK(igraph_vector_init(&al->adjs[i], 0));
    IGRAPH_CHECK(igraph_neighbors(graph, &al->adjs[i], i, mode));
  }

  IGRAPH_FINALLY_CLEAN(1);
  return 0;
}

int igraph_largest_cliques(const igraph_t *graph, igraph_vector_ptr_t *res) {
  igraph_vector_ptr_clear(res);
  IGRAPH_FINALLY(igraph_i_cliques_free_res, res);
  IGRAPH_CHECK(igraph_i_maximal_cliques(graph, &igraph_i_largest_cliques_store, (void*)res));
  IGRAPH_FINALLY_CLEAN(1);
  return IGRAPH_SUCCESS;
}

int igraph_2dgrid_init(igraph_2dgrid_t *grid, igraph_matrix_t *coords,
                       igraph_real_t minx, igraph_real_t maxx, igraph_real_t deltax,
                       igraph_real_t miny, igraph_real_t maxy, igraph_real_t deltay) {
    long int i;

    grid->coords=coords;
    grid->minx=minx;
    grid->maxx=maxx;
    grid->deltax=deltax;
    grid->miny=miny;
    grid->maxy=maxy;
    grid->deltay=deltay;

    grid->stepsx=(long int) ceil((maxx-minx)/deltax);
    grid->stepsy=(long int) ceil((maxy-miny)/deltay);

    IGRAPH_CHECK(igraph_matrix_init(&grid->startidx,
                                    grid->stepsx, grid->stepsy));
    IGRAPH_FINALLY(igraph_matrix_destroy, &grid->startidx);
    IGRAPH_VECTOR_INIT_FINALLY(&grid->next, igraph_matrix_nrow(coords));
    IGRAPH_VECTOR_INIT_FINALLY(&grid->prev, igraph_matrix_nrow(coords));

    for (i=0; i<igraph_vector_size(&grid->next); i++) {
        VECTOR(grid->next)[i]=-1;
    }

    grid->massx=0;
    grid->massy=0;
    grid->vertices=0;

    IGRAPH_FINALLY_CLEAN(3);
    return 0;
}

/**
 * \ingroup structural
 * \function igraph_similarity_jaccard_es
 * \brief Jaccard similarity coefficient for a given edge selector.
 *
 * </para><para>
 * The Jaccard similarity coefficient of two vertices is the number of common
 * neighbors divided by the number of vertices that are neighbors of at
 * least one of the two vertices being considered. This function calculates
 * the pairwise Jaccard similarities for the endpoints of edges in a given edge
 * selector.
 *
 * \param graph The graph object to analyze
 * \param res Pointer to a vector, the result of the calculation will
 *        be stored here. The number of elements is the same as the number
 *        of edges in \p es.
 * \param es An edge selector that specifies the edges to be included in the
 *        result.
 * \param mode The type of neighbors to be used for the calculation in
 *        directed graphs. Possible values:
 *        \clist
 *        \cli IGRAPH_OUT
 *          the outgoing edges will be considered for each node.
 *        \cli IGRAPH_IN
 *          the incoming edges will be considered for each node.
 *        \cli IGRAPH_ALL
 *          the directed graph is considered as an undirected one for the
 *          computation.
 *        \endclist
 * \param loops Whether to include the vertices themselves in the neighbor
 *        sets.
 * \return Error code:
 *        \clist
 *        \cli IGRAPH_ENOMEM
 *           not enough memory for temporary data.
 *        \cli IGRAPH_EINVVID
 *           invalid vertex id passed.
 *        \cli IGRAPH_EINVMODE
 *           invalid mode argument.
 *        \endclist
 * 
 * Time complexity: O(nd), n is the number of edges in the edge selector, d is
 * the (maximum) degree of the vertices in the graph.
 *
 * \sa \ref igraph_similarity_jaccard() and \ref igraph_similarity_jaccard_pairs()
 *   to calculate the Jaccard similarity between all pairs of a vertex set or
 *   some selected vertex pairs, or \ref igraph_similarity_dice(),
 *   \ref igraph_similarity_dice_pairs() and \ref igraph_similarity_dice_es() for a
 *   measure very similar to the Jaccard coefficient
 * 
 * \example examples/simple/igraph_similarity.c
 */
int igraph_similarity_jaccard_es(const igraph_t *graph, igraph_vector_t *res,
	const igraph_es_t es, igraph_neimode_t mode, igraph_bool_t loops) {
  igraph_vector_t v;
  igraph_eit_t eit;

  IGRAPH_VECTOR_INIT_FINALLY(&v, 0);

  IGRAPH_CHECK(igraph_eit_create(graph, es, &eit));
  IGRAPH_FINALLY(igraph_eit_destroy, &eit);

  while (!IGRAPH_EIT_END(eit)) {
    long int eid = IGRAPH_EIT_GET(eit);
    igraph_vector_push_back(&v, IGRAPH_FROM(graph, eid));
    igraph_vector_push_back(&v, IGRAPH_TO(graph, eid));
    IGRAPH_EIT_NEXT(eit);
  }

  igraph_eit_destroy(&eit);
  IGRAPH_FINALLY_CLEAN(1);

  IGRAPH_CHECK(igraph_similarity_jaccard_pairs(graph, res, &v, mode, loops));
  igraph_vector_destroy(&v);
  IGRAPH_FINALLY_CLEAN(1);

  return IGRAPH_SUCCESS;
}