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init solve_eqs

This commit is contained in:
Nikolaj Bjorner 2022-11-02 15:59:08 -07:00
parent 6790f18132
commit e141759768
3 changed files with 192 additions and 0 deletions

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@ -2,6 +2,7 @@ z3_add_component(simplifiers
SOURCES
euf_completion.cpp
bv_slice.cpp
solve_eqs.cpp
COMPONENT_DEPENDENCIES
euf
rewriter

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/*++
Copyright (c) 2022 Microsoft Corporation
Module Name:
solve_eqs.cpp
Abstract:
simplifier for solving equations
Author:
Nikolaj Bjorner (nbjorner) 2022-11-2.
--*/
#include "ast/simplifiers/solve_eqs.h"
namespace euf {
void solve_eqs::init() {
}
// initialize graph that maps variable ids to next ids
void solve_eqs::extract_dep_graph(dep_eq_vector& eqs) {
m_var2id.reset();
m_id2var.reset();
m_next.reset();
unsigned sz = 0;
for (auto const& [v, t, d] : eqs)
sz = std::max(sz, v->get_id());
m_var2id.resize(sz + 1, UINT_MAX);
for (auto const& [v, t, d] : eqs) {
if (is_var(v))
continue;
m_var2id[v->get_id()] = m_id2var.size();
m_id2var.push_back(v);
}
m_next.resize(m_id2var.size());
for (auto const& [v, t, d] : eqs)
m_next[var2id(v)].push_back(t);
}
void solve_eqs::add_subst(app* v, expr* term) {
}
/**
* Build a substitution while assigning levels to terms.
* The substitution is well-formed when variables are replaced with terms whose
* Free variables have higher levels.
*/
void solve_eqs::extract_subst() {
m_var2level.reset();
m_var2level.resize(m_id2var.size(), UINT_MAX);
auto is_explored = [&](unsigned id) {
return m_var2level[id] != UINT_MAX;
};
auto is_safe = [&](unsigned lvl, expr* t) {
for (auto* e : subterms::all(expr_ref(t, m)))
if (is_var(e) && m_var2level[var2id(e)] < lvl)
return false;
};
unsigned init_level = UINT_MAX;
for (unsigned id = 0; id < m_id2var.size(); ++id) {
if (is_explored(id))
continue;
// initialize current level to have enough room to assign different levels to all variables.
init_level -= m_id2var.size() + 1;
unsigned curr_level = init_level;
todo.push_back(id);
while (!todo.empty()) {
unsigned j = todo.back();
todo.pop_back();
if (is_explored(j))
continue;
m_var2level[id] = curr_level++;
for (expr* t : m_next[j]) {
if (!is_safe(curr_level, t))
continue;
add_subst(m_id2var[j], t);
for (auto* e : subterms::all(expr_ref(t, m)))
if (is_var(e) && !is_explored(var2id(e)))
todo.push_back(var2id(e));
break;
}
}
}
}
void solve_eqs::extract_subst(dep_eq_vector& eqs, dep_eq_vector& subst) {
}
void solve_eqs::apply_subst() {
}
void solve_eqs::reduce() {
init();
dep_eq_vector eqs, subst;
get_eqs(eqs);
extract_subst(eqs, subst);
apply_subst();
advance_qhead(m_fmls.size());
}
}

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/*++
Copyright (c) 2022 Microsoft Corporation
Module Name:
solve_eqs.h
Abstract:
simplifier for solving equations
Author:
Nikolaj Bjorner (nbjorner) 2022-11-2.
--*/
#pragma once
#include "ast/simplifiers/dependent_expr_state.h"
#include "ast/rewriter/th_rewriter.h"
namespace euf {
struct dependent_eq {
app* var;
expr_ref term;
expr_dependency* dep;
dependent_eq(app* var, expr_ref& term, expr_dependency* d) : var(var), term(term), dep(d) {}
};
typedef vector<dependent_eq> dep_eq_vector;
class extract_eq {
pulic:
virtual ~extract_eq() {}
virtual void get_eqs(depdendent_expr const& e, dep_eq_vector& eqs) = 0;
};
class solve_eqs : public dependent_expr_simplifier {
th_rewriter m_rewriter;
scoped_ptr_vector<extract_eq> m_extract_plugins;
unsigned_vector m_var2id;
ptr_vector<app> m_id2var;
vector<uint_set> m_next;
void init();
bool is_var(expr* v) const;
unsigned var2id(expr* v) const { return m_var2id[v->get_id()]; }
void get_eqs(dep_eq_vector& eqs) {
for (unsigned i = m_qhead; i < m_fmls.size(); ++i)
get_eqs(m_fmls[i](), eqs);
}
void get_eqs(dependent_expr const& f, dep_eq_vector& eqs) {
for (auto* ex : m_extract_plugins)
ex->get_eqs(f, eqs);
}
void extract_subst(dep_eq_vector& eqs, dep_eq_vector& subst);
void apply_subst();
public:
solve_eqs(ast_manager& m, dependent_expr_state& fmls) : dependent_expr_simplifier(m, fmls), m_rewriter(m) {}
void push() override { dependent_expr_simplifier::push(); }
void pop(unsigned n) override { dependent_expr_simplifier::pop(n); }
void reduce() override;
};
}