skeleton_pairs()

void res_comp::skeleton_pairs	(	res_pair *&	result,
		res_pair *	p )

Definition at line 1496 of file res-a1.cpp.

{
  gc_vector<Bag*> elems;
  gc_vector<int> vp;  // This is 'p'.
  gc_vector<int> thisvp;
 
  monomial PAIRS_mon = ALLOCATE_MONOMIAL(monom_size);
 
  if (M2_gbTrace >= 10)
    {
      buffer o;
      o << "Computing pairs with first = " << p->me << newline;
      emit(o.str());
    }
  M->divide(p->base_monom, p->first->base_monom, PAIRS_mon);
  M->to_varpower(PAIRS_mon, vp);
 
  // First add in syzygies arising from exterior variables
  // At the moment, there are none of this sort.
 
  if (P->is_skew_commutative())
    {
 
      exponents_t exp = newarray_atomic(int, M->n_vars());
      varpower::to_expvector(M->n_vars(), vp.data(), exp);
 
      int nskew = P->n_skew_commutative_vars();
      for (int v = 0; v < nskew; v++)
        {
          int w = P->skew_variable(v);
          if (exp[w] > 0)
            {
              thisvp.resize(0);
              varpower::var(w, 1, thisvp);
              Bag *b = new Bag(static_cast<void *>(nullptr), thisvp);
              elems.push_back(b);
            }
        }
      freemem(exp);
    }
 
  // Second, add in syzygies arising from the base ring, if any
  // The baggage of each of these is NULL
  if (P->is_quotient_ring())
    {
      const MonomialIdeal *Rideal = P->get_quotient_monomials();
      for (Bag& a : *Rideal)
        {
          // Compute (P->quotient_ideal->monom : p->monom)
          // and place this into a varpower and Bag, placing
          // that into 'elems'
          thisvp.resize(0);
          varpower::quotient(a.monom().data(), vp.data(), thisvp);
          if (varpower::is_equal(a.monom().data(), thisvp.data()))
            continue;
          Bag *b = new Bag(static_cast<void *>(nullptr), thisvp);
          elems.push_back(b);
        }
    }
 
  // Third, add in syzygies arising from previous elements of this same level
  // The baggage of each of these is their corresponding res_pair
 
  MonomialIdeal *mi_orig = p->first->mi;
  for (Bag& a : *mi_orig)
    {
      Bag *b = new Bag(a.basis_ptr());
      varpower::quotient(a.monom().data(), vp.data(), b->monom());
      elems.push_back(b);
    }
 
  // Make this monomial ideal, and then run through each minimal generator
  // and insert into the proper degree. (Notice that sorting does not
  // need to be done yet: only once that degree is about to begin.
 
  mi_orig->insert_minimal(new Bag(p, vp));
 
  MonomialIdeal *mi = new MonomialIdeal(P, elems);
 
  if (M2_gbTrace >= 11) mi->debug_out(1);
 
  for (Bag& a : *mi)
    {
      res_pair *second = reinterpret_cast<res_pair *>(a.basis_ptr());
      res_pair *q = new_res_pair(SYZ_S_PAIR, p, second);
      // That set most fields except base_monom:
      M->from_varpower(a.monom().data(), q->base_monom);
      M->mult(q->base_monom, p->base_monom, q->base_monom);
      result->next = q;
      result = q;
    }
 
  delete mi;
}

References ALLOCATE_MONOMIAL, res_pair::base_monom, MonomialIdeal::debug_out(), emit(), freemem(), MonomialIdeal::insert_minimal(), ExponentList< int, true >::is_equal(), M, M2_gbTrace, int_bag::monom(), monom_size, monomial, new_res_pair(), newarray_atomic, newline, P, p, ExponentList< int, true >::quotient(), result(), buffer::str(), SYZ_S_PAIR, ExponentList< int, true >::to_expvector(), and ExponentList< int, true >::var().

Referenced by skeleton().