  This is an introduction to Game Semantics based on some lecture notes given
at the CLiCS II summer school in Cambridge in 1995. We will focus on the recent
(1994) work on Game semantics, which has led to some striking advances in the
Full Abstraction problem for PCF and other programming languages. Our aim is to
give a genuinely elementary first introduction; we therefore present a
simplified version of game semantics, which nonetheless contains most of the
essential concepts. The more complex game semantics used by Abramsky,
Jagadeesan and Malacaria and by Hyland and Ong to construct fully abstract
models for PCF can be seen as refinements of what we present. Some background
in category theory, type theory and linear logic would be helpful in reading
these notes.
