simulate_theorem_producer.cpp

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/*****************************************************************************/
/*!
 *\file simulate_theorem_producer.cpp
 *\brief Trusted implementation of the proof rules for symbolic simulator
 *
 * Author: Sergey Berezin
 *
 * Created: Tue Oct  7 10:55:24 2003
 *
 * <hr>
 * Copyright (C) 2003 by the Board of Trustees of Leland Stanford
 * Junior University and by New York University. 
 *
 * License to use, copy, modify, sell and/or distribute this software
 * and its documentation for any purpose is hereby granted without
 * royalty, subject to the terms and conditions defined in the \ref
 * LICENSE file provided with this distribution.  In particular:
 *
 * - The above copyright notice and this permission notice must appear
 * in all copies of the software and related documentation.
 *
 * - THE SOFTWARE IS PROVIDED "AS-IS", WITHOUT ANY WARRANTIES,
 * EXPRESSED OR IMPLIED.  USE IT AT YOUR OWN RISK.
 * 
 * <hr>
 * 
 */
/*****************************************************************************/

// This code is trusted
#define _CVCL_TRUSTED_

#include "simulate_theorem_producer.h"
#include "theory_simulate.h"
#include <algorithm>

using namespace std;
using namespace CVCL;

////////////////////////////////////////////////////////////////////
// TheoryArith: trusted method for creating ArithTheoremProducer
////////////////////////////////////////////////////////////////////

SimulateProofRules* TheorySimulate::createProofRules(VCL* vcl) {
  return new SimulateTheoremProducer(vcl);
}
  
////////////////////////////////////////////////////////////////////
// Proof rules
////////////////////////////////////////////////////////////////////

Theorem SimulateTheoremProducer::expandSimulate(const Expr& e) {
  const int arity = e.arity();
  if (CHECK_PROOFS) {
    CHECK_SOUND(e.getKind() == SIMULATE, 
                "SimulateTheoremProducer::expandSimulate: "
                "expected SIMULATE expression: "
                +e.toString());
    CHECK_SOUND(arity >= 3 && e[arity - 1].isRational() && 
                e[arity - 1].getRational().isInteger(), 
                "SimulateTheoremProducer::expandSimulate: "
                "incorrect children in SIMULATE: " + e.toString());
  }

  int n = e[arity - 1].getRational().getInt();

  if(CHECK_PROOFS) {
    CHECK_SOUND(n >= 0, "SimulateTheoremProducer::expandSimulate: "
                "Requested negative number of iterations: "+int2string(n));
  }
 
  // Compute f(f(...f(f(s0, I1(0), I2(0), ...), I1(1), ...), ... ),
  //           I1(n-1), ...)
  //
  // We do this by accumulating the expression in 'res':
  // res_{i+1} = func(res_i, I1(i), ..., Ik(i))
  Expr res(e[1]);
  for(int i=0; i<n; ++i) {
    vector<Expr> args;
    args.push_back(res);
    Expr ri(newRatExpr(d_em, i));
    for(int j=2; j<arity-1; ++j)
      args.push_back(newApplyExpr(e[j], ri));
    res = newApplyExpr(e[0], args);
  }

  Assumptions a;
  Proof pf;
  if(withProof())
    pf = newPf("expand_simulate", e);
  return newRWTheorem(e, res, a, pf);
}

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