 With chess it is possible , in principle , to play a perfect game or construct a machine to do so as follows : One considers in a given position all possible moves , then all moves for the opponent , etc . , to the end of the game ( in each variation ) . The end must occur , by the rules of the games after a finite number of moves ( remembering the 50 move drawing rule ) . Each of these variations ends in win , loss or draw . By working backward from the end one can determine whether there is a forced win , the position is a draw or is lost . It is easy to show , however , even with the high computing speed available in electronic calculators this computation is impractical . In typical chess positions there will be of the order of 30 legal moves . The number holds fairly constant until the game is nearly finished as shown ... by De Groot , who averaged the number of legal moves in a large number of master games . Thus a move for White and then one for Black gives about 103 possibilities . A typical game lasts about 40 moves to resignation of one party . This is conservative for our calculation since the machine would calculate out to checkmate , not resignation . However , even at this figure there will be 10120 variations to be calculated from the initial position . A machine operating at the rate of one variation per microsecond would require over 1090 years to calculate the first move ! 
 With chess it <a href='drop_aux' title='1'><mark>is</mark></a>possible , in principle , to play a perfect game or construct a machine to do so as <a href='uninflect' title='2'><mark>follows</mark></a> : One <a href='uninflect' title='3'><mark>considers</mark></a> in a given position all possible moves , then all moves for the opponent , etc . , to the end of the game ( in each variation ) . The end must occur , by the rules of the games after a finite number of moves ( remembering the 50 move drawing rule ) . Each of these variations <a href='uninflect' title='4'><mark>ends</mark></a> in win , loss or draw . By working backward from the end one can determine whether <a href='dey_it' title='5'><mark>there</mark></a> is a forced win , the position is a draw or is lost . It <a href='drop_aux' title='6'><mark>is</mark></a>easy to show , however , even with the high computing speed available in electronic calculators this computation <a href='drop_aux' title='7'><mark>is</mark></a>impractical . In typical chess positions <a href='dey_it' title='8'><mark>there</mark></a> will be of the order of 30 legal moves . The number <a href='uninflect' title='9'><mark>holds</mark></a> fairly constant until the game is nearly finished as shown ... by De Groot , <a href='null_relcl' title='10'><mark>who</mark></a>averaged the number of legal moves in a large number of master games . Thus a move for White and then one for Black <a href='uninflect' title='11'><mark>gives</mark></a> about 103 possibilities . A typical game <a href='uninflect' title='12'><mark>lasts</mark></a> about 40 moves to resignation of one party . This <a href='drop_aux' title='13'><mark>is</mark></a>conservative for our calculation since the machine would calculate out to checkmate , not resignation . However , even at this figure <a href='dey_it' title='14'><mark>there</mark></a> will be 10120 variations to be calculated from the initial position . A machine operating at the rate of one variation per microsecond would require over 1090 years to calculate the first move ! 
With chess it possible , in principle , to play a perfect game or construct a machine to do so as follow : One consider in a given position all possible moves , then alll moves for da opponent , etc . , to tdaend of the game ( in each variation ) . The end must occur , by thdaules of the games after a finite number of moves ( remembering the 50 move drawing rule ) . Each of these variations end in win , loss or draw . By workin backward from the end one can determine whether it is a forced win , the position is a draw or is lost . It easy to show , however , even with thedagh computing speed available in electronic calculators dis computation impractical . In typical chess positions it will be of the daer of 30 legal moves . The number hold fairly constant untill the game is nearly finished as shown ... by De Groot , averaged the number of legal moves in a bigass number of master games . Thus a move for White and then one for Black give bout 103 possibilities . A typical game last abou40 moves to resignation of one party . This conservative for our calculation since the mdaine would calculate outt to checkmate , not resignation . However , even at tdisfigure it will be 10120 variations to be calculated from the initial position . A machine operating at the rate of one variation per microsecond would require over 1090 years to calculate the fida move !