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/*-----------------------------------------------------------------------
File : cpr_dpll.c
Author: Stephan Schulz
Contents
Code for the main DPLL algorithm.
Copyright 1998-2011 by the author.
This code is released under the GNU General Public Licence and
the GNU Lesser General Public License.
See the file COPYING in the main E directory for details..
Run "eprover -h" for contact information.
Changes
<1> Wed May 14 01:56:29 CEST 2003
New
-----------------------------------------------------------------------*/
#include "cpr_dpll.h"
/*---------------------------------------------------------------------*/
/* Global Variables */
/*---------------------------------------------------------------------*/
/*---------------------------------------------------------------------*/
/* Forward Declarations */
/*---------------------------------------------------------------------*/
/*---------------------------------------------------------------------*/
/* Internal Functions */
/*---------------------------------------------------------------------*/
/*-----------------------------------------------------------------------
//
// Function: deactivate_clauses()
//
// Deactivete all clauses in *tree and record them on
// state->decativated. Return number of clauses.
//
// Global Variables: -
//
// Side Effects : Changes state.
//
/----------------------------------------------------------------------*/
long deactivate_clauses(DPLLState_p state, PTree_p *clauses)
{
long res = 0;
return res;
}
/*-----------------------------------------------------------------------
//
// Function: shorten_clauses()
//
// Shorten all clauses in *tree by one.
//
// Global Variables: -
//
// Side Effects : Changes state
//
/----------------------------------------------------------------------*/
long shorten_clauses(DPLLState_p state, PTree_p *clauses)
{
long res = 0;
return res;
}
/*---------------------------------------------------------------------*/
/* Exported Functions */
/*---------------------------------------------------------------------*/
/*-----------------------------------------------------------------------
//
// Function: DPLLStateAlloc()
//
// Allocate an initialized DPLL search state.
//
// Global Variables: -
//
// Side Effects : Memory operations
//
/----------------------------------------------------------------------*/
DPLLState_p DPLLStateAlloc(DPLLFormula_p form)
{
DPLLState_p handle = DPLLStateCellAlloc();
long i, limit;
DPLLClause_p clause;
handle->form = form;
handle->assignment = PStackAlloc();
handle->deactivated = PStackAlloc();
handle->unproc_units = PStackAlloc();
handle->open_atoms = AtomSetAlloc();
for(i=1; i<form->atom_no; i++)
{
if(form->atoms[i].pos_occur + form->atoms[i].neg_occur)
{
AtomSetInsert(handle->open_atoms, i);
}
}
limit = PStackGetSP(form->clauses);
for(i=0; i<limit; i++)
{
clause = PStackElementP(form->clauses, i);
if(DPLLClauseIsUnit(clause))
{
PStackPushP(handle->unproc_units, clause);
}
}
return handle;
}
/*-----------------------------------------------------------------------
//
// Function: DPLLStateFree()
//
// Free a DPLL search state
//
// Global Variables: -
//
// Side Effects : Memory operations
//
/----------------------------------------------------------------------*/
void DPLLStateFree(DPLLState_p junk)
{
PStackFree(junk->assignment);
PStackFree(junk->deactivated);
PStackFree(junk->unproc_units);
AtomSetFree(junk->open_atoms);
DPLLFormulaFree(junk->form);
DPLLStateCellFree(junk);
}
/*-----------------------------------------------------------------------
//
// Function: DPLLAssignVar()
//
// Extend the assignment with the given new propositional variable
// assignment. Return true if no empty clause has been generated.
//
// Global Variables: -
//
// Side Effects : Changes state!
//
/----------------------------------------------------------------------*/
bool DPLLAssignVar(DPLLState_p state, PLiteralCode assignment)
{
bool res = true;
Atom_p atom;
PStackPushInt(state->assignment, assignment);
PStackPushP(state->deactivated, NULL); /* Mark new subset */
if(assignment > 0)
{
atom = &(state->form->atoms[assignment]);
deactivate_clauses(state, &(atom->pos_active));
res = shorten_clauses(state, &(atom->neg_active));
}
else
{
assignment = -assignment;
atom = &(state->form->atoms[assignment]);
deactivate_clauses(state, &(atom->pos_active));
res = shorten_clauses(state, &(atom->neg_active));
}
return res;
}
/*---------------------------------------------------------------------*/
/* End of File */
/*---------------------------------------------------------------------*/
|
