 The main topic of this entry is a logical approach to game theory, bringing classical notions and methods from logic to bear upon games. This project is sometimes called ‘logic of games’. There also is a converse direction of ‘logic as games’, where game theoretic concepts are employed to elucidate basic notions of logic. This section presents a brief discussion on this direction as a natural counterpoint to the main lines of the entry. For an extensive survey see the entries on  logic and games  and  games, abstraction and completeness.