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Fix bug probabilistic linear algebra with a linear form #287

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Merged
ederc merged 10 commits into from
Mar 13, 2026
Merged

Fix bug probabilistic linear algebra with a linear form #287

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84d8fe2
tabulation in initial_modular_step
jerebertho Mar 9, 2026
df1c775
disable verbose mode on the 2nd run of FGLM when verifying parametriz…
jerebertho Mar 9, 2026
d5080ce
restart computation when the ideal 0-dim but probabilistic linear alg…
jerebertho Mar 9, 2026
f4ff257
typo and spaces
jerebertho Mar 9, 2026
f34fe03
typo and message in verbose mode
jerebertho Mar 9, 2026
a2642e7
wrapping lines
jerebertho Mar 9, 2026
5293204
set is0dim to 1 independantly of the characteristic or the success of…
jerebertho Mar 10, 2026
e1325f2
handles the fact that probabilistic linear algebra can return a 0-dim…
jerebertho Mar 12, 2026
dc856bb
change test for wrong degree of the output of probabilistic linear al…
jerebertho Mar 12, 2026
6be2f7b
revert verbose mode when verifying the parametrizations, keep them if…
jerebertho Mar 12, 2026
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248 changes: 150 additions & 98 deletions src/msolve/msolve.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1590,59 +1590,61 @@ static int equal_param(param_t *param, param_t *test_param){
}

static int32_t *initial_modular_step(
sp_matfglm_t **bmatrix,
int32_t **bdiv_xn,
int32_t **blen_gb_xn,
int32_t **bstart_cf_gb_xn,
long **bextra_nf,
int32_t **blens_extra_nf,
int32_t **bexps_extra_nf,
int32_t **bcfs_extra_nf,

nvars_t *nlins_ptr, nvars_t *linvars,
uint32_t **lineqs_ptr, nvars_t *squvars,

fglm_data_t **bdata_fglm, fglm_bms_data_t **bdata_bms,
int32_t *num_gb,
int32_t **leadmons,
uint64_t *bsz,
param_t **bparam,
bs_t *gbg,
md_t *md,
const uint32_t fc,
const int32_t unstable_staircase,
int print_gb,
int *dim,
long *dquot_ori,
int *minpolydeg_ori,
data_gens_ff_t *gens,
files_gb *files,
int *success)
sp_matfglm_t **bmatrix,
int32_t **bdiv_xn,
int32_t **blen_gb_xn,
int32_t **bstart_cf_gb_xn,
long **bextra_nf,
int32_t **blens_extra_nf,
int32_t **bexps_extra_nf,
int32_t **bcfs_extra_nf,

nvars_t *nlins_ptr, nvars_t *linvars,
uint32_t **lineqs_ptr, nvars_t *squvars,

fglm_data_t **bdata_fglm,
fglm_bms_data_t **bdata_bms,
int32_t *num_gb,
int32_t **leadmons,
uint64_t *bsz,
param_t **bparam,
bs_t *gbg,
md_t *md,
const uint32_t fc,
const int32_t unstable_staircase,
int print_gb,
int *dim,
long *dquot_ori,
int *minpolydeg_ori,
data_gens_ff_t *gens,
files_gb *files,
int *success)
{
double rt = realtime();
double rt = realtime();

md->print_gb = print_gb;
md->f4_qq_round = 1;
md->print_gb = print_gb;
md->f4_qq_round = 1;

int32_t error = 0;
int32_t empty_solution_set = 1;
bs_t *bs = core_gba(gbg, md, &error, fc);
int32_t error = 0;
int32_t empty_solution_set = 1;
bs_t *bs = core_gba(gbg, md, &error, fc);

md->learning_rtime = realtime()-rt;
print_tracer_statistics(stdout, rt, md);
md->learning_rtime = realtime()-rt;
print_tracer_statistics(stdout, rt, md);

get_leading_ideal_information(num_gb, leadmons, 0, bs);
get_leading_ideal_information(num_gb, leadmons, 0, bs);

print_groebner_basis(files, gens, bs, md, fc);
print_groebner_basis(files, gens, bs, md, fc);

empty_solution_set = check_for_single_element_groebner_basis(
dim, dquot_ori, bs, leadmons, 0, md);
empty_solution_set = check_for_single_element_groebner_basis(dim, dquot_ori,
bs, leadmons, 0,
md);

if (empty_solution_set == 1) {
free_basis_without_hash_table(&(bs));
free(bs);
return NULL;
}
if (empty_solution_set == 1) {
free_basis_without_hash_table(&(bs));
free(bs);
return NULL;
}


check_and_set_linear_poly(nlins_ptr, linvars, lineqs_ptr, bs->ht,
Expand All @@ -1655,61 +1657,77 @@ static int32_t *initial_modular_step(
/* fprintf(stderr, "Dimension of quotient: %ld\n", dquot); */
/* } */
if(print_gb==0){
/* *bmatrix = build_matrixn_from_bs_trace(bdiv_xn, */
/* blen_gb_xn, */
/* bstart_cf_gb_xn, */
/* lmb, dquot, bs, bs->ht, */
/* leadmons[0], bs->ht->nv, */
/* fc, */
/* md->info_level); */
md->fglm_rtime = realtime();
md->fglm_ctime = cputime();
print_fglm_header (stdout,md);
*bmatrix = build_matrixn_unstable_from_bs_trace(bdiv_xn,
blen_gb_xn,
bstart_cf_gb_xn,
bextra_nf,
blens_extra_nf,
bexps_extra_nf,
bcfs_extra_nf,
lmb, dquot, bs, bs->ht,
leadmons[0], md,
bs->ht->nv,
fc, unstable_staircase,
md->info_level,
files);

if(*bmatrix == NULL){
*success = 0;
*dim = 0;
*dquot_ori = dquot;
if(md->info_level > 1){
fprintf (stdout,"------------------------------------------------------------------------------------------------------\n");
}
free_basis_without_hash_table(&(bs));
free(bs);
return NULL;
/* *bmatrix = build_matrixn_from_bs_trace(bdiv_xn, */
/* blen_gb_xn, */
/* bstart_cf_gb_xn, */
/* lmb, dquot, bs, bs->ht, */
/* leadmons[0], bs->ht->nv, */
/* fc, */
/* md->info_level); */
md->fglm_rtime = realtime();
md->fglm_ctime = cputime();
print_fglm_header (stdout,md);
*bmatrix = build_matrixn_unstable_from_bs_trace(bdiv_xn,
blen_gb_xn,
bstart_cf_gb_xn,
bextra_nf,
blens_extra_nf,
bexps_extra_nf,
bcfs_extra_nf,
lmb, dquot, bs, bs->ht,
leadmons[0], md,
bs->ht->nv,
fc, unstable_staircase,
md->info_level,
files);

if(*bmatrix == NULL){
*success = 0;
*dim = 0;
*dquot_ori = dquot;
if(md->info_level > 1){
fprintf (stdout,"------------------------------------------------------------------------------------------------------\n");
}
free_basis_without_hash_table(&(bs));
free(bs);
return NULL;
}

*bsz = bs->ht->nv - (*nlins_ptr); //nlins ;

check_and_set_vars_squared_in_monomial_basis(squvars, lmb,
dquot, gens->nvars);
dquot, gens->nvars);
*bparam = nmod_fglm_compute_trace_data(*bmatrix, fc, bs->ht->nv,
*bsz, *nlins_ptr, linvars, lineqs_ptr[0], squvars,
md->info_level, bdata_fglm, bdata_bms, success, md);
*bsz, *nlins_ptr, linvars,
lineqs_ptr[0], squvars,
md->info_level, bdata_fglm,
bdata_bms, success, md);
if((*bparam)->elim->length - 1 != dquot){
param_t **test_nmod_param =
/* reset times for change of order */
md->fglm_ctime = cputime();
md->fglm_rtime = realtime();
param_t **test_nmod_param =
(param_t **)malloc(sizeof(param_t *));
*test_nmod_param = nmod_fglm_compute_trace_data(*bmatrix, fc, bs->ht->nv,
*bsz, *nlins_ptr, linvars, lineqs_ptr[0], squvars,
0, bdata_fglm, bdata_bms, success, md);
int boo = equal_param(*bparam, *test_nmod_param);
if(boo == 0){
*success = 0;
}
free_fglm_param(test_nmod_param[0]);
free(test_nmod_param);
*test_nmod_param = nmod_fglm_compute_trace_data(
*bmatrix, fc, bs->ht->nv,
*bsz, *nlins_ptr, linvars, lineqs_ptr[0],
squvars,
0, bdata_fglm, bdata_bms, success, md);
int boo = equal_param(*bparam, *test_nmod_param);
if ((*test_nmod_param)->degelimpol == dquot) {
/* shape position
replace with the new parametrizations
necessarily correct */
free_fglm_param(bparam[0]);
*bparam = *test_nmod_param;
} else {
if(boo == 0) {
/* both parametrizations might be incorrect */
*success = 0;
}
free_fglm_param(test_nmod_param[0]);
}
free(test_nmod_param);
}
}
*dim = 0;
Expand Down Expand Up @@ -2093,9 +2111,14 @@ int is_member(uint32_t fc, primes_t *init_primes){

- returns 2 if requires more genericity.
=> (all the squares are not under the staircase)

- returns 3 if computation with a random linear form succeeded
=> charac 0 + requires a non random linear form now

- returns 4 if probabilistic F4 yields dim > 0 while it is
known to satisfy dim = 0
or returns dim = 0 with a wrong (too large) degree

- returns -2 if charac > 0

- returns -3 if meta data are not correct
Expand All @@ -2107,7 +2130,8 @@ int msolve_trace_qq(mpz_param_t *mpz_paramp,
param_t **nmod_param,
int *dim_ptr,
long *dquot_ptr,
int *minpolydeg_ptr,
int *minpolydeg_ptr,
int *is0dim_ptr,
data_gens_ff_t *gens,
int32_t ht_size, //initial_hts,
int32_t unstable_staircase,
Expand Down Expand Up @@ -2319,6 +2343,18 @@ int msolve_trace_qq(mpz_param_t *mpz_paramp,
files,
&success);


if (*is0dim_ptr == -1) {
if (*dim_ptr == 0) {
/* first run, detects that the ideal is 0-dim
and save its degree */
*is0dim_ptr= *dquot_ptr;
}
} else if (*dim_ptr > 0 || *is0dim_ptr < *dquot_ptr) {
/* another run, detects that the ideal is positive-dimensional
or has a wrong degree, too large */
return 4;
}
if (gens->field_char == 0 && gens->rand_linear) {
*minpolydeg_ptr = (*nmod_params)->degsqfrelimpol;
return 3;
Expand Down Expand Up @@ -3668,11 +3704,12 @@ void isolate_real_roots_lparam(mpz_param_array_t lparams, long **lnbr_ptr,
}

int real_msolve_qq(mpz_param_t *mpz_paramp, param_t **nmod_param, int *dim_ptr,
long *dquot_ptr, int *minpolydeg_ptr, long *nb_real_roots_ptr,
long *dquot_ptr, int *minpolydeg_ptr, int* is0dim_ptr,
long *nb_real_roots_ptr,
interval **real_roots_ptr, real_point_t **real_pts_ptr,
data_gens_ff_t *gens,
int32_t ht_size, //initial_hts,
int32_t unstable_staircase,
int32_t unstable_staircase,
int32_t nr_threads,
int32_t max_nr_pairs,
int32_t elim_block_len,
Expand Down Expand Up @@ -3706,7 +3743,8 @@ int real_msolve_qq(mpz_param_t *mpz_paramp, param_t **nmod_param, int *dim_ptr,
nmod_param,
dim_ptr,
dquot_ptr,
minpolydeg_ptr,
minpolydeg_ptr,
is0dim_ptr,
gens,
ht_size, //initial_hts,
unstable_staircase,
Expand Down Expand Up @@ -3941,6 +3979,7 @@ int core_msolve(
when over Q */
int minpolydeg = -1;
int oldminpolydeg = -1;
int is0dim = -1;

restart:

Expand Down Expand Up @@ -4424,7 +4463,8 @@ int core_msolve(
paramp,
&dim,
&dquot,
&minpolydeg,
&minpolydeg,
&is0dim,
nb_real_roots_ptr,
real_roots_ptr,
real_pts_ptr,
Expand Down Expand Up @@ -5100,7 +5140,8 @@ int core_msolve(
&param,
&dim,
&dquot,
&minpolydeg,
&minpolydeg,
&is0dim,
nb_real_roots_ptr,
real_roots_ptr,
real_pts_ptr,
Expand Down Expand Up @@ -5256,6 +5297,17 @@ int core_msolve(
}
}
}
if (b == 4){
/* Probabilistic linear algebra yields a
Groebner basis of a positive-dimensional ideal
or of a 0-dimensional ideal of wrong degree,
restart with the same linear form */
if (info_level > 0) {
fprintf (stdout, "\nWrong dimension or degree\n");
fprintf (stdout, "Restarting with the same linear form\n");
}
goto restart;
}
}

free(bld);
Expand Down
8 changes: 5 additions & 3 deletions src/msolve/msolve.h
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -32,7 +32,8 @@ int msolve_trace_qq(
param_t **nmod_param,
int *dim_ptr,
long *dquot_ptr,
int *minpolydeg_ptr,
int *minpolydeg_ptr,
int *is0dim_ptr,
data_gens_ff_t *gens,
int32_t ht_size,
int32_t unstable_staircase,
Expand All @@ -44,7 +45,7 @@ int msolve_trace_qq(
int32_t use_signatures,
int32_t lift_matrix,
int *to_split_ptr,
primes_t **binit_primes,
primes_t **binit_primes,
int32_t info_level,
int32_t print_gb,
int32_t pbm_file,
Expand Down Expand Up @@ -99,6 +100,7 @@ int real_msolve_qq(
int *dim_ptr,
long *dquot_ptr,
int *minpolydeg_ptr,
int *is0dim_ptr,
long *nb_real_roots_ptr,
interval **real_roots_ptr,
real_point_t **real_pts_ptr,
Expand Down Expand Up @@ -225,7 +227,7 @@ int64_t export_groebner_qq(
const int32_t reduce_gb,
const int32_t pbm_file,
const int32_t truncate_lifting,
const int32_t info_level
const int32_t info_level
);

// Utility functions to init and deinit data structures
Expand Down
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