diff --git a/isisd/topology/spacyc.c b/isisd/topology/spacyc.c
new file mode 100644
index 0000000..8531447
--- /dev/null
+++ b/isisd/topology/spacyc.c
@@ -0,0 +1,483 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <values.h>
+
+#include "random.c"
+
+#define DASH '-'
+#define VERY_FAR 100000000
+
+
+/* generator of acyclic random networks for the shortest paths problem;
+   extended DIMACS format for output */
+
+main ( argc, argv )
+
+int argc;
+char* argv[];
+
+{
+
+char   args[30];
+
+long   n,
+       n0,
+       source,
+       i,
+       i0,
+       j,
+       dij;
+
+long   m,
+       m0,
+       mc,
+       k;
+
+long   *p,
+       p_t,
+       l,
+       lx;
+
+long   seed,
+       seed1,
+       seed2;
+
+int    ext=0;
+
+FILE   *fout;
+
+/* variables for lengths generating */
+/* initialized by default values */
+int    l_f = 0, ll_f = 0, lm_f = 0, ln_f = 0, ls_f = 0;
+long   ll = 10000,    /* upper bound of the interval */
+       lm = 0;        /* lower bound of the interval */
+double ln = 0,        /* l += ln * |i-j| */ 
+       ls = 0;        /* l += ls * |i-j|^2 */
+
+/* variables for connecting path(s) */
+int    c_f = 0, cl_f = 0, ch_f = 0, c_rand = 1;
+long   cl = 1;        /* length of path arc */
+long   ch;            /* number of arcs in the path
+                         n - by default */
+
+/* variables for artifical source */
+int    s_f = 0, sl_f = 0, sm_f = 0;
+long   sl   = VERY_FAR, /* upper bound of artifical arc */
+       sm,              /* lower bound of artifical arc */
+       s;  
+
+/* variables for potentials */
+int    p_f = 0, pl_f = 0, pm_f = 0, pn_f = 0, ps_f = 0,
+       pa_f = 0, pap_f = 0, pac_f = 0;
+long   pl,            /* upper bound of the interval */
+       pm;            /* lower bound of the interval */
+double pn = 0,        /* l += ln * |i-j| */ 
+       ps = 0,        /* l += ls * |i-j|^2 */
+       pap = 0,       /* part of nodes with alternative dustribution */
+       pac = -1;      /* multiplier for alternative distribution */
+
+int np;               /* number of parameter parsing now */
+
+#define PRINT_ARC( i, j, length )\
+{\
+l = length;\
+if ( p_f ) l += ( p[i] - p[j] );\
+printf ("a %8ld %8ld %12ld\n", i, j, l );\
+}
+
+  /* parsing  parameters */
+
+if ( argc < 2 ) goto usage;
+
+np = 0;
+
+strcpy ( args, argv[1] );
+
+  if ( ( args[0] == DASH ) && ( args[1] == 'h')
+     )
+      goto help;
+
+if ( argc < 4 ) goto usage;
+
+/* first parameter - number of nodes */
+np = 1;
+if ( ( n = atoi ( argv[1] ) )  <  2  )  goto usage;
+
+/* second parameter - number of arcs */
+np = 2;
+if ( ( m = atoi ( argv[2] ) )  <  n  )  goto usage;
+
+/* third parameter - seed */
+np=3;
+if ( ( seed = atoi ( argv[3] ) )  <=  0  )  goto usage;
+
+/* other parameters */
+
+for ( np = 4; np < argc; np ++ )
+  {
+    strcpy ( args, argv[np] );
+    if ( args[0] != DASH ) goto usage;
+
+    switch ( args[1] )
+      {
+
+      case 'l' : /* an interval for arc length */
+	l_f = 1;
+	switch ( args[2] )
+	  { 
+	  case 'l': /* length of the interval */
+	    ll_f = 1;
+	    ll  =  (long) atof ( &args[3] );
+	    break;
+	  case 'm': /* minimal bound */
+	    lm_f = 1;
+	    lm  = (long ) atof ( &args[3] );
+	    break;
+	  case 'n': /* additional length: l*|i-j| */
+	    ln_f = 1;
+	    ln  = atof ( &args[3] );
+	    break;
+	  case 's': /* additional length: l*|i-j|^2 */
+	    ls_f = 1;
+	    ls  = atof ( &args[3] );
+	    break;
+	  default:  /* unknown switch  value */
+	    goto usage;
+	  }
+	break;
+
+      case 'c' : /* connecting path(s) */
+        c_f = 1;
+	switch ( args[2] )
+	  { 
+	  case 'l': /* length of path arc */
+            c_rand = 0; /* fixed arc length */
+	    cl_f = 1;
+	    cl  =  (long) atof ( &args[3] );
+            break;
+	  case 'h': /* number of arcs in connecting path */
+	    ch_f = 1;
+	    ch  =  (long) atof ( &args[3] );
+            if ( ch < 1 || ch > n ) goto usage;
+	    break;
+	  default:  /* unknown switch  value */
+	    goto usage;
+          }
+	break;
+
+      case 's' : /* additional source */
+        s_f = 1;
+	if ( strlen ( args ) > 2 )
+	{  
+	switch ( args[2] )
+	  { 
+	  case 'l': /* upper bound of art. arc */
+	    sl_f = 1;
+	    sl  =  (long) atof ( &args[3] );
+            break;
+	  case 'm': /* lower bound of art. arc */
+	    sm_f = 1;
+	    sm  =  (long) atof ( &args[3] );
+            break;
+	  default:  /* unknown switch  value */
+	    goto usage;
+          }
+         }
+	break;
+
+      case 'p' : /* potentials */
+	p_f = 1;
+	if ( strlen ( args ) > 2 )
+	{  
+	switch ( args[2] )
+	  { 
+	  case 'l': /* length of the interval */
+	    pl_f = 1;
+	    pl  =  (long) atof ( &args[3] );
+	    break;
+	  case 'm': /* minimal bound */
+	    pm_f = 1;
+	    pm  = (long ) atof ( &args[3] );
+	    break;
+	  case 'n': /* additional length: l*|i-j| */
+	    pn_f = 1;
+	    pn  = atof ( &args[3] );
+	    break;
+	  case 's': /* additional length: l*|i-j|^2 */
+	    ps_f = 1;
+	    ps  = atof ( &args[3] );
+	    break;
+	  case 'a': /* bipolar distribution */
+	    pa_f = 1;
+	    switch ( args[3] )
+	      {
+	      case 'p': /* % of alternative potentials */
+                pap_f = 1;
+                pap  = atof ( &args[4] );
+		if ( pap < 0   ) pap = 0;
+		if ( pap > 100 ) pap = 100;
+                pap /= 100;
+		break;
+	      case 'c': /* multiplier */
+		pac_f = 1;
+		pac = atof ( &args[4] );
+		break;
+	      default: /* unknown switch value */
+		goto usage;
+	      }
+	    break;
+	  default:  /* unknown switch  value */
+	    goto usage;
+	  }
+      }
+	break;
+
+      default  : /* unknoun case */
+	goto usage;
+      }
+  }
+   
+/* ----- ajusting parameters ----- */
+
+n0 = n; m0 = m;
+
+/* length parameters */
+if ( ll < lm ) { lx = ll; ll = lm; lm = lx; }
+
+/* potential parameters */
+if ( p_f )
+  {
+   if ( ! pl_f ) pl = ll;
+   if ( ! pm_f ) pm = lm;
+   if ( pl < pm ) { lx = pl; pl = pm; pm = lx; }
+  }
+
+/* path(s) parameters */
+if ( ! ch_f ) ch = n - 1;
+mc = n - 1;
+
+ /* artifical source parameters */
+if ( s_f )          
+   { m0 += n; n0 ++ ; 
+     if ( ! sm_f ) sm = sl;
+     if ( sl < sm ) { lx = sl; sl = sm; sm = lx; }
+   }
+
+/*----- printing title -----*/
+
+printf ("c acyclic network for shortest paths problem\n");
+printf ("c extended DIMACS format\nc\n" );
+
+
+/* name of the problem */
+printf ("t ac_%ld_%ld_%ld_", n, m, seed );
+if ( l_f )
+  printf ("%c", 'l');
+if ( c_f )
+  printf ("%c", 'c');
+if ( s_f )
+  printf ("%c", 's');
+if ( p_f )
+  printf ("%c", 'p');
+printf ("\nc\n");
+
+/* printing additional information  */
+if ( l_f )
+  printf ("c length -> min: %ld max: %ld k1: %.2f k2: %.2f\n",
+           lm, ll, ln, ls );
+if ( c_f )
+  printf ("c path(s) -> number of arcs: %ld arc length: %ld\n",
+           ch, cl );
+if ( s_f )
+  printf ("c length of arcs from artifical source -> min: %ld max: %ld\n",
+           sm, sl );
+if ( p_f )
+  {
+  printf ("c potentials -> min: %ld max: %ld k1: %.2f k2: %.2f\n",
+	  pm, pl, pn, ps );
+  if ( pa_f )
+  printf ("c potentials -> part of alternative distribution: %.2f k: %.2f\n",
+          pap, pac );
+  }
+printf ("c\n" );
+
+printf ("p sp %8ld %8ld\nc\n", n0, m0 );
+
+source = ( s_f ) ? n0 : 1;
+printf ("n %8ld\nc\n", source );
+
+
+if ( p_f ) /* generating potentials */
+  {
+    seed1 = 2*seed + 1;
+    p = (long*) calloc ( n+2, sizeof (long) );
+    init_rand ( seed1);
+    pl = pl - pm + 1;
+
+    for ( i = 0; i <= n; i ++ )
+      {
+	p_t = pm + nrand ( pl );
+	if ( pn_f ) p_t += (long) ( i * pn );
+	if ( ps_f ) p_t += (long) ( i * ( i * ps ));
+	if ( pap_f )
+	    if ( rand01() < pap )
+		p_t = (long) ( p_t * pac );
+        p[i] = p_t;
+      }
+    p[n+1] = 0;
+  }
+
+
+if ( s_f ) /* additional arcs from artifical source */
+  {
+    seed2 = 3*seed + 1;
+    init_rand ( seed2 );
+    sl = sl - sm + 1;
+
+    for ( i = n; i > 1; i -- )
+      {
+	s = sm + nrand ( sl );
+	PRINT_ARC ( n0, i, s ) 
+      }
+
+    PRINT_ARC ( n0, 1, 0 )
+  }
+
+/* initialize random number generator */
+init_rand ( seed );
+ll = ll - lm + 1;
+
+/* generating connecting path(s) */
+for ( i = 1; i < n; i ++ )
+  {
+    if ( ( (i-1) % ch ) != 0 )
+      i0 = i;
+    else
+      i0 = 1;
+
+      if (c_rand)
+        cl = lm + nrand(ll);
+      PRINT_ARC ( i0, i+1, cl )
+  }
+
+/* generating random arcs */
+
+
+for ( k = 1; k <= m - mc; k ++ )
+  {
+    i = 1 + nrand ( n );
+
+    do
+    j = 1 + nrand ( n );
+    while ( j == i );
+
+    if ( i > j )
+      { i0 = i; i = j; j = i0; }
+
+    dij = j - i;
+    l = lm + nrand ( ll );
+    if ( ln_f ) l += (long) ( dij * ln );
+    if ( ls_f ) l += (long) ( dij * ( dij * ls ) );
+    PRINT_ARC ( i, j, l );
+  }
+
+/* all is done */
+exit (ext);
+
+/* ----- wrong usage ----- */
+
+ usage:
+fprintf ( stderr,
+"\nusage: %s  n  m  seed  [ -ll#i -lm#i -cl#i -p -pl#i -pm#i ... ]\n\
+help:  %s -h\n\n", argv[0], argv[0] );
+
+if ( np > 0 )
+  fprintf ( stderr, "error in parameter # %d\n\n", np );   
+exit (4);
+
+/* ---- help ---- */
+
+ help:
+
+if ( args[2] == 'h') goto hhelp;
+
+fprintf ( stderr, 
+"\n'%s' - acyclic network generator for shortest paths problem.\n\
+Generates problems in extended DIMACS format.\n\
+\n\
+   %s  n m seed [ -ll#i -lm#i -cl#i -p -pl#i -pm#i ... ]\n\
+   %s -hh\n\
+\n\
+                        #i - integer number   #f - real number\n\
+\n\
+-ll#i  - #i is the upper bound on arc lengths          (default 10000)\n\
+-lm#i  - #i is the lower bound on arc lengths          (default 0)\n\
+-cl#i  - #i is length of arcs in connecting path(s)    (default random)\n\
+-p     - generate potentials \n\
+-pl#i  - #i is the upper bound on potentials           (default ll)\n\
+-pm#i  - #i is the lower bound on potentials           (default lm)\n\
+\n\
+-hh    - extended help \n\n",
+argv[0], argv[0], argv[0] );
+
+exit (0);
+
+/* --------- sophisticated help ------------ */
+ hhelp:
+
+if ( argc < 3 )
+     fout = stderr;
+else
+     fout = fopen ( argv[2], "w" );
+
+if ( fout == NULL )
+{ fprintf ( stderr, "\nCan't open file  '%s' for writing help\n\n", argv[2] );
+  exit ( 2 );
+}
+
+fprintf (fout, 
+"\n'%s' - acyclic network generator for shortest paths problem.\n\
+Generates problems in extended DIMACS format.\n\
+\n\
+   %s  n m seed [ -ll#i -lm#i -ln#f -ls#f\n\
+                      -p  -pl#i -pm#i -pn#f -ps#f -pap#i -pac#f\n\
+                      -cl#i -ch#i\n\
+                      -s  -sl#i -sm#i\n\
+                    ]\n\
+   %s -hh file_name\n\
+\n\
+                        #i - integer number   #f - real number\n\
+\n\
+      Arc length parameters:\n\
+-ll#i  - #i is the upper bound on arc lengths          (default 10000)\n\
+-lm#i  - #i is the lower bound on arc lengths          (default 0)\n\
+-ln#f  - multipliy l(i, j) by #f * |i-j|               (default 0)\n\
+-ls#f  - multipliy l(i, j) by #f * |i-j|^2             (default 0)\n\
+\n\
+      Potential parameters:\n\
+-p     - generate potentials \n\
+-pl#i  - #i is the upper bound on potentials           (default ll)\n\
+-pm#i  - #i is the lower bound on potentials           (default lm)\n\
+-pn#f  - multiply p(i) by #f * i                       (default 0)\n\
+-ps#f  - multiply p(i) by #f * i^2                     (default 0)\n\
+-pap#i - percentage of alternative potential nodes     (default 0)\n\
+-pac#f - if i is alternative, multiply  p(i) by #f     (default -1)\n\
+\n\
+      Connecting path(s) parameters:\n\
+-cl#i  - #i is length of arcs in connecting path(s)   (default random)\n\
+-ch#i  - #i is length of connecting path(s)           (default n-1)\n\
+\n\
+      Artificial source parameters:\n\
+-s     - generate artificial source with default connecting arc lengths\n\
+-sl#i  - #i is the upper bound on art. arc lengths    (default 100000000)\n\
+-sm#i  - #i is the lower bound on art. arc lengths    (default sl)\n\
+\n\
+-hh file_name  - save this help in the file 'file_name'\n\n",
+argv[0], argv[0], argv[0] );
+
+exit (0);
+}
+
+
+