monideal-minprimes.hpp

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// (c) 1994-2005 Michael E. Stillman
#ifndef _monideal_minprimes_h_
#define _monideal_minprimes_h_

 
#include "monideal.hpp"
 
class MinimalPrimes
// A class which enables one to compute the codimension and
// associated primes of minimal codimension, of a monomial ideal.
{
  enum { do_codim, do_primes } state;
  int min_codim;
  int nvars;
 
  MonomialIdeal *mi;  // A radical monomial ideal
 
  MonomialIdeal *primes;
  VECTOR(Bag *) Q;   // Each monomial corresponds to a potential prime monomial
                    // ideal: a monomial is the product of the gens of
                    // the prime ideal.
  int codim_limit;  // only consider monomial primes of codim <= this number.
  int minprime_limit;  // -1 means find all.  >= 1 means stop after that number
  int n_minprimes;  // number found so far, during associated_primes computation
  exponents_t *exps;
 
  int depth_limit;  // -codim_limit-1
  exponents_t exp;
  exponents_t exp2;
  int *monoms;
 
  void alg1_grab_prime(int depth);
  void alg1_min_prime_generator(int *which, int depth);
 
  void ass_prime_generator(Nmi_node *p, int codim);
 
 public:
  MinimalPrimes(const MonomialIdeal *const &mi);
 
  ~MinimalPrimes();
 
  int codimension();
 
  MonomialIdeal *associated_primes(int count);
 
  MonomialIdeal *alg1_min_primes(int maxcodim, int count);
 
  MonomialIdeal *min_primes(int maxcodim, int count);
  // maxcodim == nvars means get all of them
  // count == -1 means no limit
  // return value: A monomial ideal where each
  //  monomial prime ideal is represented as a
  //  monomial: the product of the generators.
  // NOTE: this is the complement of the gens from
  //  max_indep_sets
 
  MonomialIdeal *max_indep_sets(int count);
 
 public:
  // Static routines:
  static int codimension(const MonomialIdeal *I);
 
  static MonomialIdeal *min_primes(const MonomialIdeal *I,
                                   int maxcodim,
                                   int count);
 
  static MonomialIdeal *max_indep_sets(const MonomialIdeal *I, int count);
};
 
#endif
 
// Local Variables:
// compile-command: "make -C $M2BUILDDIR/Macaulay2/e "
// indent-tabs-mode: nil
// End: