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// Copyright 2004 Michael E. Stillman.
#include "text-io.hpp"
#include "comp-res.hpp"
#include "res-a1.hpp"
#include "res-a0.hpp"
#include "res-a2.hpp"
#include "finalize.hpp"
#include "schreyer-resolution/res-f4-computation.hpp"
#include "NCResolutions/nc-res-computation.hpp"
#include <iostream>
ResolutionComputation::ResolutionComputation() {}
ResolutionComputation::~ResolutionComputation() {}
ResolutionComputation *ResolutionComputation::choose_res(
const Matrix *m,
M2_bool resolve_cokernel,
int max_level,
M2_bool use_max_slanted_degree,
int max_slanted_degree,
int algorithm,
int strategy)
{
// The following modification is because some algorithms do not work if
// max_level is 0.
// github issue (crash, #368).
if (max_level <= 0) max_level = 1;
const Ring *R = m->get_ring();
ResolutionComputation *C = nullptr;
int origsyz;
// First, we need to check that m is homogeneous, and that
// the heft values of the variables are all positive.
// All of these algorithms also assume that R is a polynomial ring.
const M2FreeAlgebraOrQuotient *NCP = R->cast_to_M2FreeAlgebraOrQuotient();
if (NCP != nullptr)
{
if (M2_gbTrace > 0) emit_line("NC resolution");
C = createNCRes(m, max_level, strategy);
return C;
}
const PolynomialRing *P = R->cast_to_PolynomialRing();
if (P == nullptr)
{
ERROR("engine resolution strategies all require a polynomial base ring");
return nullptr;
}
const Ring* K = P->getCoefficientRing();
if (K->get_precision() != 0)
{
ERROR("free resolutions over polynomial rings with RR or CC coefficients not yet implemented");
return nullptr;
}
if (!P->getMonoid()->primary_degrees_of_vars_positive())
{
ERROR(
"engine resolution strategies all require a Heft vector which is "
"positive for all variables");
return nullptr;
}
if (algorithm < 4 and !m->is_homogeneous())
{
ERROR("engine resolution strategies require a homogeneous module");
return nullptr;
}
switch (algorithm)
{
case 1:
if (!resolve_cokernel)
{
ERROR(
"resolution Strategy=>1 cannot resolve a cokernel with a given "
"presentation: use Strategy=>2 or Strategy=>3 instead");
return nullptr;
}
if (!R->is_commutative_ring())
{
ERROR(
"use resolution Strategy=>2 or Strategy=>3 for non commutative "
"polynomial rings");
return nullptr;
}
if (M2_gbTrace > 0) emit_line("resolution Strategy=>1");
C = new res_comp(m, max_level, strategy);
break;
case 0:
if (!resolve_cokernel)
{
ERROR(
"resolution Strategy=>0 cannot resolve a cokernel with a given "
"presentation: use Strategy=>2 or Strategy=>3 instead");
return nullptr;
}
if (!R->is_commutative_ring())
{
ERROR(
"use resolution Strategy=>2 or Strategy=>3 for non commutative "
"polynomial rings");
return nullptr;
}
if (M2_gbTrace > 0) emit_line("resolution Strategy=>0");
C = new res2_comp(
m, max_level, use_max_slanted_degree, max_slanted_degree, strategy);
break;
case 2:
origsyz = m->n_cols();
if (M2_gbTrace > 0) emit_line("resolution Strategy=>2");
C = new gbres_comp(m, max_level + 1, origsyz, strategy);
break;
case 3:
origsyz = m->n_cols();
if (M2_gbTrace > 0) emit_line("resolution Strategy=>3");
C = new gbres_comp(
m, max_level + 1, origsyz, strategy | STRATEGY_USE_HILB);
break;
case 4:
case 5:
if (!resolve_cokernel)
{
ERROR(
"resolution Strategy=>4 cannot resolve a cokernel with a given "
"presentation: use Strategy=>2 or Strategy=>3 instead");
return nullptr;
}
if (!P->is_skew_commutative() and !R->is_commutative_ring())
{
ERROR(
"use resolution Strategy=>2 or Strategy=>3 for non commutative "
"polynomial rings");
return nullptr;
}
if (M2_gbTrace > 0) emit_line("resolution Strategy=>4 (res-f4)");
C = createF4Res(m, max_level, strategy);
if (C == nullptr) return nullptr;
break;
}
if (C == nullptr)
{
ERROR("unknown resolution algorithm");
return nullptr;
}
intern_res(C);
return C;
}
void ResolutionComputation::betti_init(int lo, int hi, int len, int *&bettis)
{
int z = (hi - lo + 1) * (len + 1);
bettis = newarray_atomic_clear(int, z);
}
M2_arrayint ResolutionComputation::betti_make(int lo,
int hi,
int len,
int *bettis)
{
int d, lev;
int hi1 = hi + 1;
int len1 = len + 1;
// Reset 'hi1' to reflect the top degree that occurs
for (d = hi; d >= lo; d--)
{
for (lev = 0; lev <= len; lev++)
if (bettis[lev + (len + 1) * (d - lo)] > 0)
{
hi1 = d;
break;
}
if (hi1 <= hi) break;
}
if (hi1 > hi) hi1 = hi;
// Reset 'len1' to reflect the top level that occurs
for (lev = len; lev >= 0; lev--)
{
for (d = lo; d <= hi1; d++)
if (bettis[lev + (len + 1) * (d - lo)] > 0)
{
len1 = lev;
break;
}
if (len1 <= len) break;
}
if (len1 > len) len1 = len;
int totallen = (hi1 - lo + 1) * (len1 + 1);
M2_arrayint result = M2_makearrayint(3 + totallen);
result->array[0] = lo;
result->array[1] = hi1;
result->array[2] = len1;
int next = 3;
for (d = lo; d <= hi1; d++)
for (lev = 0; lev <= len1; lev++)
result->array[next++] = bettis[lev + (len + 1) * (d - lo)];
return result;
}
void ResolutionComputation::betti_display(buffer &o, M2_arrayint ar)
{
int *a = ar->array;
int total_sum = 0;
int lo = a[0];
int hi = a[1];
int len = a[2] + 1;
o << "total ";
for (int lev = 0; lev < len; lev++)
{
int sum = 0;
for (int d = lo; d <= hi; d++) sum += a[len * (d - lo) + lev + 3];
total_sum += sum;
o.put(sum, 6);
o << ' ';
}
o << " [" << total_sum << "]" << newline;
for (int d = lo; d <= hi; d++)
{
o.put(d, 5);
o << ": ";
for (int lev = 0; lev < len; lev++)
{
int c = a[len * (d - lo) + lev + 3];
if (c != 0)
o.put(c, 6);
else
o << " -";
o << " ";
}
o << newline;
}
}
MutableMatrix /* or null */ *ResolutionComputation::get_matrix(int level,
int degree)
{
// the default version gives an error that it isn't defined
ERROR("this function not defined for this resolution type");
return 0;
}
// Local Variables:
// compile-command: "make -C $M2BUILDDIR/Macaulay2/e "
// indent-tabs-mode: nil
// End:
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