A modern program of this type called Stockfish may have been used by Borislav Ivanov at the 2012 Zadar Open.  
Richard Greenblatt declined MIT's offer for a PhD in exchange for writing a thesis on a program of this type he wrote in one week on a PDP-6.  Greenblatt's program of this type, MacHack, was used to counter a 1965 RAND Corporation memo written by Herbert Dreyfus.  In 2015, Baudsurfer broke a long-standing record by writing a program of this type in just 487 bytes.  Hackers at MIT used a primitive network connection between the PDP-1 and TX-0 to fool (*) John McCarthy into thinking they had written a program of this type.  A modern program of this type called Stockfish may have been used by Borislav Ivanov at the 2012 Zadar Open.  Perhaps the most famous program to do this was based on Feng-hsiung Hsu's work at Carnegie Mellon on Deep Thought and won a 1997 contest.  For 10 points, name this game played by IBM's Deep Blue, which beat Garry Kasparov.
Richard Greenblatt declined MIT's offer for a PhD in exchange for writing a thesis on a program of this type he wrote in one week on a PDP-6.  
chess program [or chess AI]