diff --git a/Makefile.am b/Makefile.am
index 5bc7bcf..2d40e85 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -14,7 +14,7 @@ lib_LTLIBRARIES = NautyTracesInterface.la
 NautyTracesInterface_la_SOURCES = src/NautyTracesInterface.c
 NautyTracesInterface_la_CPPFLAGS = $(GAP_CPPFLAGS) $(NAUTY_CPPFLAGS) -DCONFIG_H
 # Note that the latter is only for GAP 4.4.12
-NautyTracesInterface_la_LDFLAGS = $(NAUTY_PATH)/nauty.o $(NAUTY_PATH)/nautil.o $(NAUTY_PATH)/naugraph.o $(NAUTY_PATH)/schreier.o $(NAUTY_PATH)/naurng.o $(NAUTY_PATH)/naugroup.o $(NAUTY_PATH)/nautinv.o -module -avoid-version
+NautyTracesInterface_la_LDFLAGS = $(NAUTY_PATH)/nauty.o $(NAUTY_PATH)/nautil.o $(NAUTY_PATH)/naugraph.o $(NAUTY_PATH)/schreier.o $(NAUTY_PATH)/naurng.o $(NAUTY_PATH)/naugroup.o $(NAUTY_PATH)/nautinv.o -module -avoid-version $(NAUTY_PATH)/nauty.a
 if SYS_IS_CYGWIN
 NautyTracesInterface_la_LDFLAGS += -no-undefined -version-info 0:0:0 -Wl,$(GAPROOT)/bin/$(GAPARCH)/gap.dll
 endif
diff --git a/src/NautyTracesInterface.c b/src/NautyTracesInterface.c
index 5f605e4..bfa129a 100644
--- a/src/NautyTracesInterface.c
+++ b/src/NautyTracesInterface.c
@@ -6,6 +6,9 @@
 #include <nauty.h>
 #include <naugroup.h>
 #include <nautinv.h>
+#include "nausparse.h"
+#include <gtools.h>
+
 
 static Obj automorphism_list;
 Obj TheTypeNautyInternalGraphObject;
@@ -33,6 +36,7 @@ Obj NautyObjTypeFunc(Obj o)
 #define IS_NAUTY_GRAPH_OBJ(o) (TNUM_OBJ(o) == T_NAUTY_OBJ)
 
 #define NAUTY_GRAPH_PTR(o) (graph*)ADDR_OBJ(o)[0]
+#define NAUTY_GRAPH_PTR_SPARSE(o) (sparsegraph*)ADDR_OBJ(o)[0]
 #define NAUTY_GRAPH_SIZE(o) (size_t)ADDR_OBJ(o)[1]
 #define NAUTY_GRAPH_ROWS(o) (size_t)ADDR_OBJ(o)[2]
 #define NAUTY_GRAPH_COLS(o) (size_t)ADDR_OBJ(o)[3]
@@ -48,6 +52,17 @@ Obj NEW_NAUTY_GRAPH_OBJ(graph* graph_pointer, size_t size, size_t rows, size_t c
     return o;
 }
 
+Obj NEW_NAUTY_SPARSEGRAPH_OBJ(sparsegraph* graph_pointer, size_t size, size_t rows, size_t cols )
+{
+    Obj o;
+    o = NewBag(T_NAUTY_OBJ, 4 * sizeof(Obj));
+    ADDR_OBJ(o)[0] = (Obj)(graph_pointer);
+    ADDR_OBJ(o)[1] = (Obj)(size);
+    ADDR_OBJ(o)[2] = (Obj)(rows);
+    ADDR_OBJ(o)[3] = (Obj)(cols);
+    return o;
+}
+
 void NautyObjFreeFunc( Obj o )
 {
     DYNFREE(ADDR_OBJ(o)[0],ADDR_OBJ(o)[1]);
@@ -102,6 +117,29 @@ Obj NAUTY_GRAPH(Obj self, Obj source_list, Obj range_list, Obj nr_vertices_gap,
     return NEW_NAUTY_GRAPH_OBJ( g, g_sz, n, m );
 }
 
+
+Obj NAUTY_DENSE_TO_SPARSE(Obj self, Obj nauty_graph )
+{
+
+    int n,m,v;
+
+    graph* g = NAUTY_GRAPH_PTR( nauty_graph );
+    size_t g_sz = NAUTY_GRAPH_SIZE( nauty_graph );
+    n = NAUTY_GRAPH_ROWS( nauty_graph );
+    m = NAUTY_GRAPH_COLS( nauty_graph );
+
+
+    DYNALLSTAT(sparsegraph,sg,sg_sz);
+    DYNALLOC2(sparsegraph,sg,sg_sz,m,n,"malloc");
+    EMPTYGRAPH(sg,m,n);
+
+    nauty_to_sg(g,sg,m,n);
+
+    return NEW_NAUTY_SPARSEGRAPH_OBJ( sg, sg_sz, n, m );
+}
+
+
+
 Obj NAUTY_DENSE(Obj self, Obj nauty_graph, Obj is_directed, Obj color_data )
 {
     DYNALLSTAT(graph,cg,cg_sz);
@@ -201,6 +239,136 @@ Obj NAUTY_DENSE(Obj self, Obj nauty_graph, Obj is_directed, Obj color_data )
     return return_list;
 }
 
+
+
+
+
+Obj NAUTY_SPARSE(Obj self, Obj nauty_graph, Obj is_directed, Obj color_data )
+{
+    DYNALLSTAT(sparsegraph,csg,csg_sz);
+    DYNALLSTAT(int,lab,lab_sz);
+    DYNALLSTAT(int,ptn,ptn_sz);
+    DYNALLSTAT(int,orbits,orbits_sz);
+    static optionblk options;
+    if( is_directed == True ){
+      static DEFAULTOPTIONS_DIGRAPH(temp_options);
+      options=temp_options;
+    }else{
+      static DEFAULTOPTIONS_SPARSEGRAPH(temp_options2);
+      options=temp_options2;
+    }
+    
+    statsblk stats;
+
+    int n,m,v;
+    set *gv;
+    
+    int nr_edges;
+    
+    int len_source;
+    int len_range;
+    
+    int current_source;
+    int current_range;
+    
+    Obj p;
+    UInt4               *ptr;
+    
+    UInt global_list;
+    
+    sparsegraph* sg = NAUTY_GRAPH_PTR_SPARSE( nauty_graph );
+    size_t sg_sz = NAUTY_GRAPH_SIZE( nauty_graph );
+    n = NAUTY_GRAPH_ROWS( nauty_graph );
+    m = NAUTY_GRAPH_COLS( nauty_graph );
+    
+    // Write automorphisms
+    global_list = GVarName( "__NAUTYTRACESINTERFACE_GLOBAL_AUTOMORPHISM_GROUP_LIST" );
+    automorphism_list = NEW_PLIST(T_PLIST, 0);
+    SET_LEN_PLIST( automorphism_list, 0 );
+    AssGVar( global_list, automorphism_list );
+    options.userautomproc = userautomproc;
+    
+    options.getcanon = TRUE;
+
+    nauty_check(WORDSIZE,m,n,NAUTYVERSIONID);
+    
+    // Allocate graph
+    DYNALLOC2(sparsegraph,csg,csg_sz,m,n,"malloc");
+    DYNALLOC1(int,lab,lab_sz,n,"malloc");
+    DYNALLOC1(int,ptn,ptn_sz,n,"malloc");
+    DYNALLOC1(int,orbits,orbits_sz,n,"malloc");
+
+    EMPTYGRAPH(csg,m,n);
+    
+    if( color_data != False ){
+        
+        options.defaultptn = FALSE;
+        
+        Obj obj_lab = ELM_PLIST( color_data, 1 );
+        Obj obj_ptn = ELM_PLIST( color_data, 2 );
+        
+        for(int i=0;i<n;i++){
+            lab[ i ] = INT_INTOBJ( ELM_PLIST( obj_lab, i + 1 ) ) - 1;
+            ptn[ i ] = INT_INTOBJ( ELM_PLIST( obj_ptn, i + 1 ) );
+        }
+    }
+    
+    // Call nauty
+    sparsenauty(sg,lab,ptn,orbits,&options,&stats,csg);
+    
+    //Convert labeling permutation
+    p   = NEW_PERM4(n);
+    ptr = ADDR_PERM4(p);
+    
+    for(int v= 0; v < n; v++){
+      ptr[v] = lab[v];
+    }
+    
+    Obj return_list = NEW_PLIST( T_PLIST, 2 );
+    SET_LEN_PLIST( return_list, 2 );
+    
+    SET_ELM_PLIST( return_list, 1, automorphism_list );
+    SET_ELM_PLIST( return_list, 2, p );
+    
+    automorphism_list = NEW_PLIST(T_PLIST, 0);
+    SET_LEN_PLIST( automorphism_list, 0 );
+    AssGVar( global_list, automorphism_list );
+    
+    DYNFREE(csg,csg_sz);
+    DYNFREE(lab,lab_sz);
+    DYNFREE(ptn,ptn_sz);
+    DYNFREE(orbits,orbits_sz);
+    
+    return return_list;
+}
+
+
+Obj NAUTY_SPARSE_GRAPH_PRINT_TEST(Obj self, Obj nauty_graph)
+{
+
+    int n,m;
+
+    sparsegraph* g = NAUTY_GRAPH_PTR_SPARSE( nauty_graph );
+
+    putgraph_sg(stderr, g, 0);
+    return True;
+}
+
+
+Obj NAUTY_DENSE_GRAPH_PRINT_TEST(Obj self, Obj nauty_graph)
+{
+
+    int n,m;
+
+    graph* g = NAUTY_GRAPH_PTR( nauty_graph );
+    n = NAUTY_GRAPH_ROWS( nauty_graph );
+    m = NAUTY_GRAPH_COLS( nauty_graph );
+
+    putgraph(stderr, g, 0, m, n);
+    return True;
+}
+
+
 Obj NautyDense(Obj self, Obj source_list, Obj range_list, Obj nr_vertices_gap, Obj is_directed, Obj color_data )
 {
     Obj graph, return_list;
@@ -210,6 +378,19 @@ Obj NautyDense(Obj self, Obj source_list, Obj range_list, Obj nr_vertices_gap, O
     return return_list;
 }
 
+
+Obj NautySparse(Obj self, Obj source_list, Obj range_list, Obj nr_vertices_gap, Obj is_directed, Obj color_data )
+{
+    Obj graph, graph2, return_list;
+    graph = NAUTY_GRAPH(self, source_list,range_list,nr_vertices_gap,is_directed);
+    NautyObjFreeFunc( graph );
+    graph2 = NAUTY_DENSE_TO_SPARSE(self, graph);
+    return_list = NAUTY_SPARSE( self, graph2, is_directed, color_data );
+    NautyObjFreeFunc( graph2 );
+    return return_list;
+}
+
+
 typedef Obj (* GVarFunc)(/*arguments*/);
 
 #define GVAR_FUNC_TABLE_ENTRY(srcfile, name, nparam, params) \
@@ -221,8 +402,13 @@ typedef Obj (* GVarFunc)(/*arguments*/);
 // Table of functions to export
 static StructGVarFunc GVarFuncs [] = {
     GVAR_FUNC_TABLE_ENTRY("NautyTracesInterface.c", NautyDense, 5, "source_list,range_list,n,is_directed,color_data"),
+    GVAR_FUNC_TABLE_ENTRY("NautyTracesInterface.c", NautySparse, 5, "source_list,range_list,n,is_directed,color_data"),
     GVAR_FUNC_TABLE_ENTRY("NautyTracesInterface.c", NAUTY_GRAPH, 4, "source_list,range_list,n,is_directed" ),
+    GVAR_FUNC_TABLE_ENTRY("NautyTracesInterface.c", NAUTY_DENSE_TO_SPARSE, 1, "source_list" ),
     GVAR_FUNC_TABLE_ENTRY("NautyTracesInterface.c", NAUTY_DENSE, 3, "graph,is_directed,color_data" ),
+    GVAR_FUNC_TABLE_ENTRY("NautyTracesInterface.c", NAUTY_SPARSE, 3, "graph,is_directed,color_data" ),
+    GVAR_FUNC_TABLE_ENTRY("NautyTracesInterface.c", NAUTY_DENSE_GRAPH_PRINT_TEST, 1, "graph" ),
+    GVAR_FUNC_TABLE_ENTRY("NautyTracesInterface.c", NAUTY_SPARSE_GRAPH_PRINT_TEST, 1, "graph" ),
 
 	{ 0 } /* Finish with an empty entry */