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/*
* richard-atp-engine: A saturation-based automated theorem prover for first-order logic.
* Copyright (C) 2026 Richard Qin
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include "atp/proof/proof_trace.h"
#include "atp/core/clause.h"
#include "atp/core/symbol_table.h"
#include "atp/core/term.h"
#include "atp/core/types.h"
#include <algorithm>
#include <stack>
#include <string>
#include <unordered_set>
#include <vector>
namespace atp {
// ─── extractProof
// DFS from empty clause back to axioms, collect all participating clauses,
// then reverse for topological order (axioms first).
std::vector<ProofStep> extractProof(const ClauseStore& store, ClauseId empty_clause_id) {
std::vector<ProofStep> steps;
std::unordered_set<ClauseId> visited;
std::stack<ClauseId> worklist;
worklist.push(empty_clause_id);
while (!worklist.empty()) {
ClauseId cid = worklist.top();
worklist.pop();
if (cid == kInvalidId) {
continue;
}
if (visited.count(cid) > 0) {
continue;
}
visited.insert(cid);
const Clause& c = store.getClause(cid);
steps.push_back({
.clause_id = cid,
.rule = c.rule,
.parent1 = c.parent1,
.parent2 = c.parent2,
});
// Recurse into parents (axioms have kInvalidId parents, which are
// filtered by the check at the top of the loop)
worklist.push(c.parent1);
worklist.push(c.parent2);
}
// Reverse: axioms (leaves) first → empty clause (root) last
std::ranges::reverse(steps);
return steps;
}
// ─── termToString
std::string termToString(TermId id, const TermBank& bank) {
const Term& t = bank.getTerm(id);
std::string name(bank.symbols().getName(t.symbol_id));
if (t.args.empty()) {
return name;
}
std::string result = name + "(";
for (size_t i = 0; i < t.args.size(); ++i) {
if (i > 0) {
result += ",";
}
result += termToString(t.args[i], bank);
}
result += ")";
return result;
}
// ─── clauseToString
std::string clauseToString(const Clause& clause, const TermBank& bank) {
if (clause.isEmpty()) {
return "□";
}
std::string result;
for (size_t i = 0; i < clause.literals.size(); ++i) {
if (i > 0) {
result += " ∨ ";
}
if (!clause.literals[i].is_positive) {
result += "¬";
}
result += termToString(clause.literals[i].atom, bank);
}
return result;
}
// ─── ruleToString
static std::string ruleToString(InferenceRule rule) {
switch (rule) {
case InferenceRule::kInput: return "input";
case InferenceRule::kResolution: return "resolution";
case InferenceRule::kFactoring: return "factoring";
default: return "unknown";
}
}
// ─── formatProof
std::string formatProof(const std::vector<ProofStep>& proof,
const ClauseStore& store, const TermBank& bank) {
std::string result;
for (size_t i = 0; i < proof.size(); ++i) {
const auto& step = proof[i];
const Clause& c = store.getClause(step.clause_id);
result += std::to_string(i + 1) + ". ";
result += "[" + ruleToString(step.rule) + "] ";
result += "c" + std::to_string(step.clause_id) + ": ";
result += clauseToString(c, bank);
// Show parents for derived clauses
if (step.parent1 != kInvalidId) {
result += " [from c" + std::to_string(step.parent1);
if (step.parent2 != kInvalidId) {
result += ", c" + std::to_string(step.parent2);
}
result += "]";
}
result += "\n";
}
return result;
}
} // namespace atp
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