source: git/Singular/LIB/rwalk.lib @ ede2ad8

/////////////////////////////////////////////////
version="version rwalk.lib 4.0.0.0 Jun_2014 ";
category="Commutative Algebra";

info="
LIBRARY: rwalk.lib   Groebner Walk Conversion Algorithms
AUTHOR: Stephan Oberfranz

PROCEDURES:
rwalk(ideal,int,int[,intvec,intvec]);   standard basis of ideal via Random Walk algorithm
rwalk(ideal,int[,intvec,intvec]);       standard basis of ideal via Random Perturbation Walk algorithm
frwalk(ideal,int[,intvec,intvec]);      standard basis of ideal via Random Fractal Walk algorithm
";

/***********************************
 * Argument string for Random Walk *
 ***********************************/
static proc OrderStringalp_NP(string Wpal,list #)
{
  int n= nvars(basering);
  string order_str = "dp";

  int nP = 1;

  //Default: if size(#)=0, the Groebnerwalk algorithm and its developments compute
  //a Groebner basis from "dp" to "lp"

  intvec curr_weight = system("Mivdp",n); //define (1,1,...,1)
  intvec target_weight = system("Mivlp",n); //define (1,0,...,0)

  if(size(#) != 0)
  {
    if(size(#) == 1)
    {
      if(typeof(#[1]) == "intvec") {
        curr_weight = #[1];

        if(Wpal == "al"){
          order_str = "(a("+string(#[1])+"),lp("+string(n) + "),C)";
        }
        if(Wpal == "M"){
          order_str = "(M("+string(#[1])+"),C)";
        }
        else {
          order_str = "(Wp("+string(#[1])+"),C)";
        }
      }
      else {
        if(typeof(#[1]) == "int"){
          nP = #[1];
        }
        else {
          print("// ** the input must be \"(ideal, int)\" or ");
          print("// **                   \"(ideal, intvec)\"");
          print("// ** a lex. GB will be computed from \"dp\" to \"lp\"");
        }
      }
    }
    else
    {
     if(size(#) == 2)
     {
       if(typeof(#[1]) == "intvec" and typeof(#[2]) == "int"){
         curr_weight = #[1];

         if(Wpal == "al"){
           order_str = "(a("+string(#[1])+"),lp("+string(n) + "),C)";
         }
         if(Wpal == "M"){
          order_str = "(M("+string(#[1])+"),C)";
         }
         else {
           order_str = "(Wp("+string(#[1])+"),C)";
         }
       }
       else{
         if(typeof(#[1]) == "intvec" and typeof(#[2]) == "intvec"){
           curr_weight = #[1];
           target_weight = #[2];

           if(Wpal == "al"){
             order_str = "(a("+string(#[1])+"),lp("+string(n) + "),C)";
           }
           if(Wpal == "M"){
             order_str = "(M("+string(#[1])+"),C)";
           }
           else {
             order_str = "(Wp("+string(#[1])+"),C)";
           //  order_str = "(a("+string(#[1])+"),C)";
           }
         }
         else{
           print("// ** the input  must be \"(ideal,intvec,int)\" or ");
           print("// **                    \"(ideal,intvec,intvec)\"");
           print("// ** and a lex. GB will be computed from \"dp\" to \"lp\"");
         }
       }
     }
     else {
       if(size(#) == 3) {
         if(typeof(#[1]) == "intvec" and typeof(#[2]) == "intvec" and
            typeof(#[3]) == "int")
         {
           curr_weight = #[1];
           target_weight = #[2];
           nP = #[3];
           if(Wpal == "al"){
             order_str = "(a("+string(#[1])+"),lp("+string(n) + "),C)";
           }
           if(Wpal == "M"){
             order_str = "(M("+string(#[1])+"),C)";
           }
           else {
             order_str = "(Wp("+string(#[1])+"),C)";
           }
         }
         else{
           print("// ** the input must be \"(ideal,intvec,intvec,int)\"");
           print("// ** and a lex. GB will be computed from \"dp\" to \"lp\"");

         }
       }
       else{
         print("// ** The given input is wrong");
         print("// ** and a lex. GB will be computed from \"dp\" to \"lp\"");
       }
     }
    }
  }

  list result;
  result[1] = nP;
  result[2] = order_str;
  result[3] = curr_weight;
  result[4] = target_weight;

  return(result);
}

/****************
 * Random Walk  *
 ****************/
proc rwalk(ideal Go, int radius, int pert_deg, list #)
"SYNTAX: rwalk(ideal i, int radius);
         if size(#)>0 then rwalk(ideal i, int radius, intvec v, intvec w);
TYPE:    ideal
PURPOSE: compute the standard basis of the ideal, calculated via
         the Random walk algorithm  from the ordering
         \"(a(v),lp)\", \"dp\", \"Dp\" or \"M\"
         to the ordering  \"(a(w),lp)\", \"(a(1,0,...,0),lp)\" or \"M\".
SEE ALSO: std, stdfglm, groebner, gwalk, pwalk, fwalk, twalk, awalk1, awalk2
KEYWORDS: Groebner walk
EXAMPLE: example rwalk; shows an example"
{
//--------------------  Initialize parameters  ------------------------
int n= nvars(basering);
list OSCTW = OrderStringalp_NP("al",#);
if(size(#)>1)
  {
  if(size(#[2]) == n*n)
    {
    OSCTW= OrderStringalp_NP("M", #);
    }
  }
else
  {
  OSCTW= OrderStringalp_NP("al", #);
  }
string ord_str = OSCTW[2];
intvec curr_weight = OSCTW[3]; // original weight vector
intvec target_weight = OSCTW[4]; // target weight vector
kill OSCTW;

//--------------------  Initialize parameters  ------------------------
def xR = basering;
execute("ring ostR = "+charstr(xR)+",("+varstr(xR)+"),"+ord_str+";");
def old_ring = basering;

ideal G = fetch(xR, Go);
G = system("Mrwalk", G, curr_weight, target_weight, radius, pert_deg, basering);

setring xR;
kill Go;

keepring basering;
ideal result = fetch(old_ring, G);
attrib(result,"isSB",1);
return (result);
}
example
{
  "EXAMPLE:"; echo = 2;
  // compute a Groebner basis of I w.r.t. lp.
  ring r = 32003,(z,y,x), lp;
  ideal I = y3+xyz+y2z+xz3, 3+xy+x2y+y2z;
  int radius = 1;
  int perturb_deg = 2;
  rwalk(I,radius,perturb_deg);
}

/*****************************************
 * Perturbation Walk with random element *
 *****************************************/
proc prwalk(ideal Go, int radius, int o_pert_deg, int t_pert_deg, list #)
"SYNTAX: rwalk(ideal i, int radius);
         if size(#)>0 then rwalk(ideal i, int radius, intvec v, intvec w);
TYPE:    ideal
PURPOSE: compute the standard basis of the ideal, calculated via
         the Random Perturbation Walk algorithm  from the ordering
         \"(a(v),lp)\", \"dp\", \"Dp\" or \"M\"
         to the ordering  \"(a(w),lp)\", \"(a(1,0,...,0),lp)\" or \"M\".
SEE ALSO: std, stdfglm, groebner, gwalk, pwalk, fwalk, twalk, awalk1, awalk2
KEYWORDS: Groebner walk
EXAMPLE: example rwalk; shows an example"
{
//--------------------  Initialize parameters  ------------------------
list OSCTW = OrderStringalp_NP("al", #);
if(size(#)>1)
  {
  if(size(#[2]) == n*n)
    {
    OSCTW= OrderStringalp_NP("M", #);
    }
  }
else
  {
  OSCTW= OrderStringalp_NP("al", #);
  }
string ord_str = OSCTW[2];
intvec curr_weight = OSCTW[3]; // original weight vector
intvec target_weight = OSCTW[4]; // target weight vector
kill OSCTW;

//--------------------  Initialize parameters  ------------------------
def xR = basering;
execute("ring ostR = ("+charstr(xR)+"),("+varstr(xR)+"),"+ord_str+";");
def old_ring = basering;

ideal G = fetch(xR, Go);
G = system("Mprwalk", G, curr_weight, target_weight, radius, o_pert_deg, t_pert_deg, basering);

setring xR;
kill Go;

keepring basering;
ideal result = fetch(old_ring, G);
attrib(result,"isSB",1);
return (result);
}
example
{
  "EXAMPLE:"; echo = 2;
  // compute a Groebner basis of I w.r.t. lp.
  ring r = 32003,(z,y,x), lp;
  ideal I = y3+xyz+y2z+xz3, 3+xy+x2y+y2z;
  int radius = 1;
  int o_perturb_deg = 2;
  int t_perturb_deg = 2;
  prwalk(I,radius,o_perturb_deg,t_perturb_deg);
}

/************************************
 * Fractal Walk with random element *
 ************************************/
proc frandwalk(ideal Go, int radius, list #)
"SYNTAX: frwalk(ideal i, int radius);
         frwalk(ideal i, int radius, intvec v, intvec w);
TYPE:    ideal
PURPOSE: compute the standard basis of the ideal, calculated via
         the Random Fractal walk algorithm  from the ordering
         \"(a(v),lp)\", \"dp\", \"Dp\" or \"M\"
         to the ordering  \"(a(w),lp)\", \"(a(1,0,...,0),lp)\" or \"M\".
SEE ALSO: std, stdfglm, groebner, gwalk, pwalk, twalk, awalk1, awalk2
KEYWORDS: The fractal walk algorithm
EXAMPLE: example frwalk; shows an example"
{
   // we use ring with ordering (a(...),lp,C)
   list OSCTW    = OrderStringalp_NP("al", #);
   if(size(#)>1)
   {
     if(size(#[2]) == n*n)
     {
       OSCTW= OrderStringalp_NP("M", #);
     }
   }
  else
  {
    OSCTW= OrderStringalp_NP("al", #);
  }
   string ord_str =   OSCTW[2];
   intvec curr_weight   =   OSCTW[3]; /* current weight vector */
   intvec target_weight =   OSCTW[4]; /* target weight vector */
   kill OSCTW;
   def xR = basering;

   execute("ring ostR = ("+charstr(xR)+"),("+varstr(xR)+"),"+ord_str+";");
   def old_ring = basering;
   //print("//** help ring = " + string(basering));
   ideal G = fetch(xR, Go);
   int pert_deg = 2;
   G = system("Mfrwalk", G, curr_weight, target_weight, radius);

   setring xR;
   //kill Go;

   keepring basering;
   ideal result = fetch(old_ring, G);
   attrib(result,"isSB",1);
   return (result);
}
example
{
    "EXAMPLE:"; echo = 2;
    ring r = 0,(z,y,x), lp;
    ideal I = y3+xyz+y2z+xz3, 3+xy+x2y+y2z;
    frandwalk(I,2);
}