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mv util/lp to math/lp
Signed-off-by: Lev Nachmanson <levnach@hotmail.com>
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Lev Nachmanson
parent
b6513b8e2d
commit
33cbd29ed0
150 changed files with 524 additions and 479 deletions
351
src/math/lp/var_eqs.h
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351
src/math/lp/var_eqs.h
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/*++
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Copyright (c) 2017 Microsoft Corporation
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Module Name:
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<name>
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Abstract:
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<abstract>
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Author:
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Nikolaj Bjorner (nbjorner)
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Lev Nachmanson (levnach)
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Revision History:
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--*/
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#pragma once
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#include "util/union_find.h"
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#include "math/lp/nla_defs.h"
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#include "util/rational.h"
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#include "math/lp/explanation.h"
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#include "math/lp/incremental_vector.h"
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namespace nla {
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class eq_justification {
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lpci m_cs[4];
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public:
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eq_justification(std::initializer_list<lpci> cs) {
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int i = 0;
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for (lpci c: cs) {
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m_cs[i++] = c;
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}
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for (; i < 4; i++) {
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m_cs[i] = -1;
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}
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}
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void explain(lp::explanation& e) const {
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for (lpci c : m_cs)
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if (c + 1 != 0) // c != -1
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e.add(c);
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}
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};
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template <typename T>
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class var_eqs {
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struct eq_edge {
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signed_var m_var;
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eq_justification m_just;
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eq_edge(signed_var v, eq_justification const& j): m_var(v), m_just(j) {}
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};
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struct var_frame {
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signed_var m_var;
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unsigned m_index;
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var_frame(signed_var v, unsigned i): m_var(v), m_index(i) {}
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};
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struct stats {
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unsigned m_num_explain_calls;
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unsigned m_num_explains;
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stats() { memset(this, 0, sizeof(*this)); }
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};
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T* m_merge_handler;
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union_find<var_eqs> m_uf;
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lp::incremental_vector<std::pair<signed_var, signed_var>>
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m_trail;
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vector<svector<eq_edge>> m_eqs; // signed_var.index() -> the edges adjacent to signed_var.index()
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trail_stack<var_eqs> m_stack;
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mutable svector<var_frame> m_todo;
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mutable svector<bool> m_marked;
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mutable unsigned_vector m_marked_trail;
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mutable svector<eq_justification> m_justtrail;
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mutable stats m_stats;
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public:
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var_eqs(): m_merge_handler(nullptr), m_uf(*this), m_stack(*this) {}
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/**
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\brief push a scope */
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void push() {
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m_trail.push_scope();
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m_stack.push_scope();
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}
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/**
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\brief pop n scopes
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*/
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void pop(unsigned n) {
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unsigned old_sz = m_trail.peek_size(n);
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for (unsigned i = m_trail.size(); i-- > old_sz; ) {
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auto const& sv = m_trail[i];
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m_eqs[sv.first.index()].pop_back();
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m_eqs[sv.second.index()].pop_back();
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m_eqs[(~sv.first).index()].pop_back();
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m_eqs[(~sv.second).index()].pop_back();
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}
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m_trail.pop_scope(n);
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m_stack.pop_scope(n); // this cass takes care of unmerging through union_find m_uf
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}
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/**
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\brief merge equivalence classes for v1, v2 with justification j
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*/
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void merge(signed_var v1, signed_var v2, eq_justification const& j) {
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unsigned max_i = std::max(v1.index(), v2.index()) + 2;
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m_eqs.reserve(max_i);
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while (m_uf.get_num_vars() <= max_i) m_uf.mk_var();
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m_trail.push_back(std::make_pair(v1, v2));
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m_uf.merge(v1.index(), v2.index());
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m_uf.merge((~v1).index(), (~v2).index());
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m_eqs[v1.index()].push_back(eq_edge(v2, j));
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m_eqs[v2.index()].push_back(eq_edge(v1, j));
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m_eqs[(~v1).index()].push_back(eq_edge(~v2, j));
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m_eqs[(~v2).index()].push_back(eq_edge(~v1, j));
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}
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void merge_plus(lpvar v1, lpvar v2, eq_justification const& j) { merge(signed_var(v1, false), signed_var(v2, false), j); }
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void merge_minus(lpvar v1, lpvar v2, eq_justification const& j) { merge(signed_var(v1, false), signed_var(v2, true), j); }
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/**
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\brief find equivalence class representative for v
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*/
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signed_var find(signed_var v) const {
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if (v.index() >= m_uf.get_num_vars()) {
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return v;
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}
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unsigned idx = m_uf.find(v.index());
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return signed_var(idx);
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}
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inline signed_var find(lpvar j) const {
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return find(signed_var(j, false));
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}
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inline bool is_root(lpvar j) const {
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signed_var sv = find(signed_var(j, false));
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return sv.var() == j;
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}
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inline bool is_root(svector<lpvar> v) const {
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for (lpvar j : v)
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if (! is_root(j))
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return false;
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return true;
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}
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bool vars_are_equiv(lpvar j, lpvar k) const {
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signed_var sj = find(signed_var(j, false));
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signed_var sk = find(signed_var(k, false));
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return sj.var() == sk.var();
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}
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/**
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\brief Returns eq_justifications for
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\pre find(v1) == find(v2)
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*/
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void explain_dfs(signed_var v1, signed_var v2, lp::explanation& e) const {
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SASSERT(find(v1) == find(v2));
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if (v1 == v2) {
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return;
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}
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m_todo.push_back(var_frame(v1, 0));
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m_justtrail.reset();
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m_marked.reserve(m_eqs.size(), false);
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SASSERT(m_marked_trail.empty());
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m_marked[v1.index()] = true;
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m_marked_trail.push_back(v1.index());
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while (true) {
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SASSERT(!m_todo.empty());
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var_frame& f = m_todo.back();
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signed_var v = f.m_var;
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if (v == v2) {
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break;
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}
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auto const& next = m_eqs[v.index()];
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bool seen_all = true;
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unsigned sz = next.size();
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for (unsigned i = f.m_index; seen_all && i < sz; ++i) {
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eq_edge const& jv = next[i];
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signed_var v3 = jv.m_var;
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if (!m_marked[v3.index()]) {
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seen_all = false;
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f.m_index = i + 1;
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m_todo.push_back(var_frame(v3, 0));
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m_justtrail.push_back(jv.m_just);
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m_marked_trail.push_back(v3.index());
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m_marked[v3.index()] = true;
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}
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}
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if (seen_all) {
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m_todo.pop_back();
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m_justtrail.pop_back();
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}
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}
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for (eq_justification const& j : m_justtrail) {
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j.explain(e);
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}
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m_stats.m_num_explains += m_justtrail.size();
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m_stats.m_num_explain_calls++;
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m_todo.reset();
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m_justtrail.reset();
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for (unsigned idx : m_marked_trail) {
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m_marked[idx] = false;
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}
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m_marked_trail.reset();
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// IF_VERBOSE(2, verbose_stream() << (double)m_stats.m_num_explains / m_stats.m_num_explain_calls << "\n");
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}
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void explain_bfs(signed_var v1, signed_var v2, lp::explanation& e) const {
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SASSERT(find(v1) == find(v2));
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if (v1 == v2) {
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return;
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}
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m_todo.push_back(var_frame(v1, 0));
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m_justtrail.push_back(eq_justification({}));
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m_marked.reserve(m_eqs.size(), false);
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SASSERT(m_marked_trail.empty());
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m_marked[v1.index()] = true;
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m_marked_trail.push_back(v1.index());
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unsigned head = 0;
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for (; ; ++head) {
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var_frame& f = m_todo[head];
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signed_var v = f.m_var;
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if (v == v2) {
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break;
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}
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auto const& next = m_eqs[v.index()];
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unsigned sz = next.size();
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for (unsigned i = sz; i-- > 0; ) {
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eq_edge const& jv = next[i];
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signed_var v3 = jv.m_var;
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if (!m_marked[v3.index()]) {
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m_todo.push_back(var_frame(v3, head));
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m_justtrail.push_back(jv.m_just);
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m_marked_trail.push_back(v3.index());
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m_marked[v3.index()] = true;
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}
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}
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}
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while (head != 0) {
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m_justtrail[head].explain(e);
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head = m_todo[head].m_index;
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++m_stats.m_num_explains;
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}
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++m_stats.m_num_explain_calls;
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m_todo.reset();
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m_justtrail.reset();
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for (unsigned idx : m_marked_trail) {
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m_marked[idx] = false;
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}
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m_marked_trail.reset();
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// IF_VERBOSE(2, verbose_stream() << (double)m_stats.m_num_explains / m_stats.m_num_explain_calls << "\n");
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}
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inline void explain(signed_var v1, signed_var v2, lp::explanation& e) const {
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explain_bfs(v1, v2, e);
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}
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inline void explain(lpvar v1, lpvar v2, lp::explanation & e) const {
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return explain(signed_var(v1, false), signed_var(v2, false), e);
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}
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inline void explain(lpvar j, lp::explanation& e) const {
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signed_var s(j, false);
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return explain(find(s), s, e);
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}
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// iterates over the class of lpvar(m_idx)
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class iterator {
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var_eqs& m_ve; // context.
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unsigned m_idx; // index into a signed variable, same as union-find index
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bool m_touched; // toggle between initial and final state
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public:
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iterator(var_eqs& ve, unsigned idx, bool t) : m_ve(ve), m_idx(idx), m_touched(t) {}
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signed_var operator*() const {
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return signed_var(m_idx);
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}
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iterator& operator++() { m_idx = m_ve.m_uf.next(m_idx); m_touched = true; return *this; }
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bool operator==(iterator const& other) const { return m_idx == other.m_idx && m_touched == other.m_touched; }
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bool operator!=(iterator const& other) const { return m_idx != other.m_idx || m_touched != other.m_touched; }
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};
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class eq_class {
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var_eqs& m_ve;
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signed_var m_v;
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public:
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eq_class(var_eqs& ve, signed_var v) : m_ve(ve), m_v(v) {}
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iterator begin() { return iterator(m_ve, m_v.index(), false); }
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iterator end() { return iterator(m_ve, m_v.index(), true); }
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};
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eq_class equiv_class(signed_var v) { return eq_class(*this, v); }
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eq_class equiv_class(lpvar v) { return equiv_class(signed_var(v, false)); }
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std::ostream& display(std::ostream& out) const {
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m_uf.display(out);
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unsigned idx = 0;
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for (auto const& edges : m_eqs) {
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if (!edges.empty()) {
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auto v = signed_var(idx);
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out << v << " root: " << find(v) << " : ";
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for (auto const& jv : edges) {
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out << jv.m_var << " ";
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}
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out << "\n";
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}
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++idx;
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}
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return out;
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}
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// union find event handlers
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void set_merge_handler(T* mh) { m_merge_handler = mh; }
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// this method is required by union_find
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trail_stack<var_eqs> & get_trail_stack() { return m_stack; }
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void unmerge_eh(unsigned i, unsigned j) {
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if (m_merge_handler) {
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m_merge_handler->unmerge_eh(signed_var(i), signed_var(j));
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}
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}
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void merge_eh(unsigned r2, unsigned r1, unsigned v2, unsigned v1) {
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if (m_merge_handler) {
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m_merge_handler->merge_eh(signed_var(r2), signed_var(r1),
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signed_var(v2), signed_var(v1));
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}
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}
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void after_merge_eh(unsigned r2, unsigned r1, unsigned v2, unsigned v1) {
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if (m_merge_handler) {
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m_merge_handler->after_merge_eh(signed_var(r2), signed_var(r1),
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signed_var(v2), signed_var(v1));
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}
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}
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}; // end of var_eqs
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template <typename T>
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std::ostream& operator<<(var_eqs<T> const& ve, std::ostream& out) { return ve.display(out); }
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}
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