Merge pull request #1874 from flintlib/notring

Generic structures shouldn't be rings by default
flintlib · Mar 22, 2024 · 2843ebb · 2843ebb
2 parents 1d534ea + a7e7115
commit 2843ebb
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Showing 5 changed files with 14 additions and 2 deletions.
diff --git a/src/gr/cmp_coercion.c b/src/gr/cmp_coercion.c
@@ -11,6 +11,8 @@
 
 #include "gr.h"
 
+/* todo: make overloadable */
+/* todo: deal correctly with structures having the same kind */
 /* todo: deal correctly with nested structures */
 
 int gr_ctx_cmp_coercion(gr_ctx_t ctx1, gr_ctx_t ctx2)

diff --git a/src/gr/mpoly.c b/src/gr/mpoly.c
@@ -87,6 +87,13 @@ _gr_gr_mpoly_ctx_set_gen_names(gr_ctx_t ctx, const char ** s)
     return GR_SUCCESS;
 }
 
+/* todo: everything is a ring when there are 0 vars? */
+truth_t
+_gr_gr_mpoly_ctx_is_ring(gr_ctx_t ctx)
+{
+    return gr_ctx_is_ring(MPOLYNOMIAL_ELEM_CTX(ctx));
+}
+
 truth_t
 _gr_gr_mpoly_ctx_is_commutative_ring(gr_ctx_t ctx)
 {
@@ -308,7 +315,7 @@ gr_method_tab_input _gr__gr_gr_mpoly_methods_input[] =
 {
     {GR_METHOD_CTX_WRITE,   (gr_funcptr) _gr_gr_mpoly_ctx_write},
     {GR_METHOD_CTX_CLEAR,   (gr_funcptr) _gr_gr_mpoly_ctx_clear},
-    {GR_METHOD_CTX_IS_RING,     (gr_funcptr) gr_generic_ctx_predicate_true},  /* todo: matrices over semirings? */
+    {GR_METHOD_CTX_IS_RING,     (gr_funcptr) _gr_gr_mpoly_ctx_is_ring},
     {GR_METHOD_CTX_IS_COMMUTATIVE_RING, (gr_funcptr) _gr_gr_mpoly_ctx_is_commutative_ring},
     {GR_METHOD_CTX_IS_INTEGRAL_DOMAIN,  (gr_funcptr) _gr_gr_mpoly_ctx_is_integral_domain},
     {GR_METHOD_CTX_IS_FIELD,            (gr_funcptr) _gr_gr_mpoly_ctx_is_field},

diff --git a/src/gr/perm.c b/src/gr/perm.c
@@ -224,6 +224,7 @@ gr_method_tab_input _perm_methods_input[] =
 {
     {GR_METHOD_CTX_IS_FINITE,
                             (gr_funcptr) gr_generic_ctx_predicate_true},
+    {GR_METHOD_CTX_IS_RING, (gr_funcptr) gr_generic_ctx_predicate_false},
     {GR_METHOD_CTX_IS_MULTIPLICATIVE_GROUP,
                             (gr_funcptr) gr_generic_ctx_predicate_true},
     {GR_METHOD_CTX_WRITE,   (gr_funcptr) _gr_perm_ctx_write},

diff --git a/src/gr_generic/generic.c b/src/gr_generic/generic.c
@@ -2518,7 +2518,7 @@ const gr_method_tab_input _gr_generic_methods[] =
 {
     {GR_METHOD_CTX_CLEAR,               (gr_funcptr) gr_generic_ctx_clear},
 
-    {GR_METHOD_CTX_IS_RING,             (gr_funcptr) gr_generic_ctx_predicate_true},
+    {GR_METHOD_CTX_IS_RING,             (gr_funcptr) gr_generic_ctx_predicate},
     {GR_METHOD_CTX_IS_COMMUTATIVE_RING, (gr_funcptr) gr_generic_ctx_predicate},
     {GR_METHOD_CTX_IS_INTEGRAL_DOMAIN,  (gr_funcptr) gr_generic_ctx_predicate},
     {GR_METHOD_CTX_IS_FIELD,            (gr_funcptr) gr_generic_ctx_predicate},

diff --git a/src/python/flint_ctypes.py b/src/python/flint_ctypes.py
@@ -439,6 +439,8 @@ def is_ring(self):
             False
             >>> PSL2Z.is_ring()
             False
+            >>> SymmetricGroup(5).is_ring()
+            False
             >>> PolynomialRing(RF).is_ring()
             False
             >>> PowerSeriesRing(RF).is_ring()