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enumpure.cc
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enumpure.cc
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//
// This file is part of Gambit
// Copyright (c) 1994-2010, The Gambit Project (http://www.gambit-project.org)
//
// FILE: src/tools/enumpure/enumpure.cc
// Compute pure-strategy equilibria in extensive form games
//
// 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 2 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, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//
#include <unistd.h>
#include <stdlib.h>
#include <iostream>
#include "libgambit/libgambit.h"
#include "libgambit/subgame.h"
using namespace Gambit;
template <class T>
void PrintProfile(std::ostream &p_stream,
const MixedBehavProfile<T> &p_profile)
{
p_stream << "NE,";
for (int i = 1; i <= p_profile.Length(); i++) {
p_stream << p_profile[i];
if (i < p_profile.Length()) {
p_stream << ',';
}
}
p_stream << std::endl;
}
List<MixedBehavProfile<Rational> > SolveBehav(const BehavSupport &p_support,
bool p_print = false)
{
List<MixedBehavProfile<Rational> > solutions;
Game efg = p_support.GetGame();
for (BehavIterator citer(p_support); !citer.AtEnd(); citer++) {
bool isNash = true;
for (GamePlayerIterator player = efg->Players();
isNash && !player.AtEnd(); player++) {
Rational current = citer->GetPayoff<Rational>(player);
for (int iset = 1; isNash && iset <= player->NumInfosets(); iset++) {
GameInfoset infoset = player->GetInfoset(iset);
for (int act = 1; act <= infoset->NumActions(); act++) {
GameAction action = infoset->GetAction(act);
if (citer->GetActionValue<Rational>(action) > current) {
isNash = false;
break;
}
}
}
}
if (isNash) {
MixedBehavProfile<Rational> temp(efg);
// zero out all the entries, since any equilibria are pure
((Vector<Rational> &) temp).operator=(Rational(0));
for (GamePlayerIterator player = efg->Players();
!player.AtEnd(); player++) {
for (int iset = 1; iset <= player->NumInfosets(); iset++) {
temp(citer->GetAction(player->GetInfoset(iset))) = 1;
}
}
if (p_print) {
PrintProfile(std::cout, temp);
}
solutions.Append(temp);
}
}
return solutions;
}
List<MixedBehavProfile<Rational> >
SubsolveBehav(const BehavSupport &p_support)
{
return SolveBehav(p_support, false);
}
template <class T>
void PrintProfile(std::ostream &p_stream,
const MixedStrategyProfile<T> &p_profile)
{
p_stream << "NE,";
for (int i = 1; i <= p_profile.MixedProfileLength(); i++) {
p_stream << p_profile[i];
if (i < p_profile.MixedProfileLength()) {
p_stream << ',';
}
}
p_stream << std::endl;
}
void SolveMixed(Game p_nfg)
{
for (StrategyIterator citer(p_nfg); !citer.AtEnd(); citer++) {
bool flag = true;
for (GamePlayerIterator player = p_nfg->Players();
flag && !player.AtEnd(); player++) {
Rational current = (*citer)->GetPayoff(player);
PureStrategyProfile p = (*citer)->Copy();
for (GameStrategyIterator strategy = player->Strategies();
!strategy.AtEnd(); strategy++) {
if (p->GetStrategyValue(strategy) > current) {
flag = false;
break;
}
}
}
if (flag) {
MixedStrategyProfile<Rational> temp(p_nfg->NewMixedStrategyProfile(Rational(0)));
((Vector<Rational> &) temp).operator=(Rational(0));
PureStrategyProfile profile = (*citer)->Copy();
for (GamePlayerIterator player = p_nfg->Players();
!player.AtEnd(); player++) {
temp[profile->GetStrategy(player)] = 1;
}
PrintProfile(std::cout, temp);
}
}
}
void PrintBanner(std::ostream &p_stream)
{
p_stream << "Search for Nash equilibria in pure strategies\n";
p_stream << "Gambit version " VERSION ", Copyright (C) 1994-2010, The Gambit Project\n";
p_stream << "This is free software, distributed under the GNU GPL\n\n";
}
void PrintHelp(char *progname)
{
PrintBanner(std::cerr);
std::cerr << "Usage: " << progname << " [OPTIONS]\n";
std::cerr << "Accepts game on standard input.\n";
std::cerr << "With no options, locates all Nash equilibria in pure strategies.\n\n";
std::cerr << "Options:\n";
std::cerr << " -S use strategic game\n";
std::cerr << " -P find only subgame-perfect equilibria\n";
std::cerr << " -h print this help message\n";
std::cerr << " -q quiet mode (suppresses banner)\n";
exit(1);
}
int main(int argc, char *argv[])
{
opterr = 0;
bool quiet = false, useStrategic = false, bySubgames = false;
int c;
while ((c = getopt(argc, argv, "hqSP")) != -1) {
switch (c) {
case 'S':
useStrategic = true;
break;
case 'P':
bySubgames = true;
break;
case 'h':
PrintHelp(argv[0]);
break;
case 'q':
quiet = true;
break;
case '?':
if (isprint(optopt)) {
std::cerr << argv[0] << ": Unknown option `-" << ((char) optopt) << "'.\n";
}
else {
std::cerr << argv[0] << ": Unknown option character `\\x" << optopt << "`.\n";
}
return 1;
default:
abort();
}
}
if (!quiet) {
PrintBanner(std::cerr);
}
try {
Game game = ReadGame(std::cin);
if (!game->IsTree() || useStrategic) {
game->BuildComputedValues();
SolveMixed(game);
}
else {
if (bySubgames) {
List<MixedBehavProfile<Rational> > solutions;
solutions = SolveBySubgames<Rational>(BehavSupport(game),
&SubsolveBehav);
for (int i = 1; i <= solutions.Length(); i++) {
PrintProfile(std::cout, solutions[i]);
}
}
else {
SolveBehav(game, true);
}
}
return 0;
}
catch (InvalidFileException) {
std::cerr << "Error: Game not in a recognized format.\n";
return 1;
}
catch (...) {
std::cerr << "Error: An internal error occurred.\n";
return 1;
}
}