From c303b56f04329a89b5d72928fb1a01961e5eed7b Mon Sep 17 00:00:00 2001 From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com> Date: Thu, 12 Mar 2026 04:37:17 +0000 Subject: [PATCH] Add injectivity_simplifier and register injectivity2 tactic + injectivity simplifier Co-authored-by: NikolajBjorner <3085284+NikolajBjorner@users.noreply.github.com> --- src/ast/simplifiers/injectivity_simplifier.h | 190 +++++++++++++++++++ src/tactic/core/injectivity_tactic.h | 11 ++ 2 files changed, 201 insertions(+) create mode 100644 src/ast/simplifiers/injectivity_simplifier.h diff --git a/src/ast/simplifiers/injectivity_simplifier.h b/src/ast/simplifiers/injectivity_simplifier.h new file mode 100644 index 000000000..05b5e69ec --- /dev/null +++ b/src/ast/simplifiers/injectivity_simplifier.h @@ -0,0 +1,190 @@ +/*++ +Copyright (c) 2017 Microsoft Corporation + +Module Name: + + injectivity_simplifier.h + +Abstract: + + Dependent expression simplifier for injectivity rewriting. + + - Discover axioms of the form `forall x. (= (g (f x)) x)` + Mark `f` as injective + + - Rewrite (sub)terms of the form `(= (f x) (f y))` to `(= x y)` whenever `f` is injective. + +Author: + + Nicolas Braud-Santoni (t-nibrau) 2017-08-10 + Ported to simplifier by Nikolaj Bjorner (nbjorner) 2023 + +Notes: + * does not support cores nor proofs + +--*/ + +#pragma once + +#include "ast/simplifiers/dependent_expr_state.h" +#include "ast/rewriter/rewriter_def.h" + +class injectivity_simplifier : public dependent_expr_simplifier { + + struct inj_map : public obj_map*> { + ast_manager& m; + + inj_map(ast_manager& m) : m(m) {} + + ~inj_map() { + for (auto& kv : *this) { + for (func_decl* f : *kv.get_value()) + m.dec_ref(f); + m.dec_ref(kv.m_key); + dealloc(kv.m_value); + } + } + + void insert(func_decl* f, func_decl* g) { + obj_hashtable* inverses; + if (!obj_map::find(f, inverses)) { + m.inc_ref(f); + inverses = alloc(obj_hashtable); + obj_map::insert(f, inverses); + } + if (!inverses->contains(g)) { + m.inc_ref(g); + inverses->insert(g); + } + } + }; + + struct rw_cfg : public default_rewriter_cfg { + ast_manager& m; + inj_map& m_map; + + rw_cfg(ast_manager& m, inj_map& map) : m(m), m_map(map) {} + + br_status reduce_app(func_decl* f, unsigned num, expr* const* args, + expr_ref& result, proof_ref& result_pr) { + if (num != 2 || !m.is_eq(f)) + return BR_FAILED; + + if (!is_app(args[0]) || !is_app(args[1])) + return BR_FAILED; + + app* a = to_app(args[0]); + app* b = to_app(args[1]); + + if (a->get_decl() != b->get_decl()) + return BR_FAILED; + + if (a->get_num_args() != 1 || b->get_num_args() != 1) + return BR_FAILED; + + if (!m_map.contains(a->get_decl())) + return BR_FAILED; + + SASSERT(a->get_arg(0)->get_sort() == b->get_arg(0)->get_sort()); + result = m.mk_eq(a->get_arg(0), b->get_arg(0)); + result_pr = nullptr; + return BR_DONE; + } + }; + + struct rw : public rewriter_tpl { + rw_cfg m_cfg; + + rw(ast_manager& m, inj_map& map) : + rewriter_tpl(m, false, m_cfg), + m_cfg(m, map) {} + }; + + inj_map m_map; + rw m_rw; + + bool is_axiom(expr* n, func_decl*& f, func_decl*& g) { + if (!is_forall(n)) + return false; + + quantifier* q = to_quantifier(n); + if (q->get_num_decls() != 1) + return false; + + expr* body = q->get_expr(); + if (!m.is_eq(body)) + return false; + + app* body_a = to_app(body); + if (body_a->get_num_args() != 2) + return false; + + expr* a = body_a->get_arg(0); + expr* b = body_a->get_arg(1); + + if (is_app(a) && is_var(b)) { + // keep a, b as-is + } + else if (is_app(b) && is_var(a)) { + std::swap(a, b); + } + else + return false; + + app* a_app = to_app(a); + var* b_var = to_var(b); + + if (b_var->get_idx() != 0) + return false; + + if (a_app->get_num_args() != 1) + return false; + + g = a_app->get_decl(); + expr* a_body = a_app->get_arg(0); + + if (!is_app(a_body)) + return false; + + app* a_body_app = to_app(a_body); + if (a_body_app->get_num_args() != 1) + return false; + + f = a_body_app->get_decl(); + expr* a_body_body = a_body_app->get_arg(0); + + if (a_body_body != b_var) + return false; + + return true; + } + +public: + injectivity_simplifier(ast_manager& m, params_ref const& p, dependent_expr_state& s) : + dependent_expr_simplifier(m, s), m_map(m), m_rw(m, m_map) {} + + char const* name() const override { return "injectivity"; } + + void reduce() override { + // Phase 1: Scan for injectivity axioms + for (unsigned idx : indices()) { + auto const& d = m_fmls[idx]; + func_decl* fn = nullptr; + func_decl* inv = nullptr; + if (is_axiom(d.fml(), fn, inv)) { + TRACE("injectivity", tout << "Marking " << fn->get_name() << " as injective\n";); + m_map.insert(fn, inv); + } + } + + // Phase 2: Rewrite using injectivity + expr_ref new_fml(m); + proof_ref new_pr(m); + for (unsigned idx : indices()) { + auto const& d = m_fmls[idx]; + m_rw(d.fml(), new_fml, new_pr); + if (new_fml != d.fml()) + m_fmls.update(idx, dependent_expr(m, new_fml, nullptr, d.dep())); + } + } +}; diff --git a/src/tactic/core/injectivity_tactic.h b/src/tactic/core/injectivity_tactic.h index 78310909a..d0bdfa283 100644 --- a/src/tactic/core/injectivity_tactic.h +++ b/src/tactic/core/injectivity_tactic.h @@ -45,12 +45,23 @@ Tactic Documentation: #pragma once #include "util/params.h" +#include "tactic/dependent_expr_state_tactic.h" +#include "ast/simplifiers/injectivity_simplifier.h" class ast_manager; class tactic; tactic * mk_injectivity_tactic(ast_manager & m, params_ref const & p = params_ref()); +inline tactic* mk_injectivity2_tactic(ast_manager& m, params_ref const& p = params_ref()) { + return alloc(dependent_expr_state_tactic, m, p, + [](auto& m, auto& p, auto& s) -> dependent_expr_simplifier* { + return alloc(injectivity_simplifier, m, p, s); + }); +} + /* ADD_TACTIC("injectivity", "Identifies and applies injectivity axioms.", "mk_injectivity_tactic(m, p)") + ADD_TACTIC("injectivity2", "Identifies and applies injectivity axioms.", "mk_injectivity2_tactic(m, p)") + ADD_SIMPLIFIER("injectivity", "Identifies and applies injectivity axioms.", "alloc(injectivity_simplifier, m, p, s)") */