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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/>.
*/
#pragma once
/// @file clausifier.h
/// @brief Converts FOL formulas to Clause Normal Form (CNF).
///
/// Clausifier is a stateful object because:
/// 1. Skolem function counter must be shared across all formulas in a problem
/// (otherwise different formulas generate conflicting Skolem names).
/// 2. Variable renaming counter must be shared for the same reason.
///
/// Pipeline: eliminate ↔/→ → NNF → Skolemize → distribute ∨ over ∧ → flatten.
#include "atp/core/clause.h"
#include "atp/core/symbol_table.h"
#include "atp/core/term_bank.h"
#include "atp/normalize/formula.h"
#include <vector>
namespace atp {
/// Stateful clausifier. Create one per proof problem.
///
/// Usage:
/// Clausifier clausifier(bank, symbols);
/// auto clauses1 = clausifier.clausify(formula1);
/// auto clauses2 = clausifier.clausify(formula2);
/// // Skolem IDs are unique across both calls.
class Clausifier {
public:
Clausifier(TermBank& bank, SymbolTable& symbols);
/// Convert a single formula to CNF clauses.
/// Skolem functions generated here are globally unique (counter persists).
[[nodiscard]] std::vector<Clause> clausify(const Formula& formula);
/// Negate a formula: wraps it in ¬(...)
/// Used to negate the conjecture before clausification.
[[nodiscard]] static std::unique_ptr<Formula> negate(std::unique_ptr<Formula> formula);
/// Number of Skolem functions generated so far.
[[nodiscard]] uint32_t skolemCount() const { return next_skolem_id_; }
private:
TermBank& bank_;
SymbolTable& symbols_;
uint32_t next_skolem_id_ = 0;
uint32_t next_var_id_ = 0; ///< For variable standardization apart
};
} // namespace atp
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