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fix empty set declaration, add axioms and rewrites

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2025-10-27 18:18:46 +01:00
parent 4630373a97
commit 4464ab9431
6 changed files with 180 additions and 122 deletions
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97
src/ast/rewriter/finite_set_rewriter.cpp
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@ -47,78 +47,87 @@ br_status finite_set_rewriter::mk_app_core(func_decl * f, unsigned num_args, exp
}
br_status finite_set_rewriter::mk_union(unsigned num_args, expr * const * args, expr_ref & result) {
VERIFY(num_args == 2);
// Idempotency: set.union(x, x) -> x
if (num_args == 2 && args[0] == args[1]) {
if (args[0] == args[1]) {
result = args[0];
return BR_DONE;
}
// Identity: set.union(x, empty) -> x or set.union(empty, x) -> x
if (num_args == 2) {
if (u.is_empty(args[0])) {
result = args[1];
return BR_DONE;
}
if (u.is_empty(args[1])) {
if (u.is_empty(args[0])) {
result = args[1];
return BR_DONE;
}
if (u.is_empty(args[1])) {
result = args[0];
return BR_DONE;
}
// Absorption: set.union(x, set.intersect(x, y)) -> x
expr *a1, *a2;
if (u.is_intersect(args[1], a1, a2)) {
if (args[0] == a1 || args[0] == a2) {
result = args[0];
return BR_DONE;
}
// Absorption: set.union(x, set.intersect(x, y)) -> x
expr* a1, *a2;
if (u.is_intersect(args[1], a1, a2)) {
if (args[0] == a1 || args[0] == a2) {
result = args[0];
return BR_DONE;
}
}
// Absorption: set.union(set.intersect(x, y), x) -> x
if (u.is_intersect(args[0], a1, a2)) {
if (args[1] == a1 || args[1] == a2) {
result = args[1];
return BR_DONE;
}
}
// Absorption: set.union(set.intersect(x, y), x) -> x
if (u.is_intersect(args[0], a1, a2)) {
if (args[1] == a1 || args[1] == a2) {
result = args[1];
return BR_DONE;
}
}
return BR_FAILED;
}
br_status finite_set_rewriter::mk_intersect(unsigned num_args, expr * const * args, expr_ref & result) {
if (num_args != 2)
return BR_FAILED;
// Idempotency: set.intersect(x, x) -> x
if (num_args == 2 && args[0] == args[1]) {
if (args[0] == args[1]) {
result = args[0];
return BR_DONE;
}
// Annihilation: set.intersect(x, empty) -> empty or set.intersect(empty, x) -> empty
if (num_args == 2) {
if (u.is_empty(args[0])) {
if (u.is_empty(args[0])) {
result = args[0];
return BR_DONE;
}
if (u.is_empty(args[1])) {
result = args[1];
return BR_DONE;
}
// Absorption: set.intersect(x, set.union(x, y)) -> x
expr *a1, *a2;
if (u.is_union(args[1], a1, a2)) {
if (args[0] == a1 || args[0] == a2) {
result = args[0];
return BR_DONE;
}
if (u.is_empty(args[1])) {
}
// Absorption: set.intersect(set.union(x, y), x) -> x
if (u.is_union(args[0], a1, a2)) {
if (args[1] == a1 || args[1] == a2) {
result = args[1];
return BR_DONE;
}
// Absorption: set.intersect(x, set.union(x, y)) -> x
expr* a1, *a2;
if (u.is_union(args[1], a1, a2)) {
if (args[0] == a1 || args[0] == a2) {
result = args[0];
return BR_DONE;
}
}
// Absorption: set.intersect(set.union(x, y), x) -> x
if (u.is_union(args[0], a1, a2)) {
if (args[1] == a1 || args[1] == a2) {
result = args[1];
return BR_DONE;
}
}
}
expr *l1, *l2, *u1, *u2;
if (u.is_range(args[0], l1, u1) && u.is_range(args[1], l2, u2)) {
arith_util a(m);
auto max_l = m.mk_ite(a.mk_ge(l1, l2), l1, l2);
auto min_u = m.mk_ite(a.mk_ge(u1, u2), u2, u1);
result = u.mk_range(max_l, min_u);
return BR_REWRITE_FULL;
}
return BR_FAILED;