(Bristol)

Quasi-inductive definitions can be considered a generalisation of the more common monotone inductive definitions, and we shall look at some examples that have arisen independently in philosophical theories of truth, in transfinite computation theory, and (much more briefly) in attempts to separate out various complexity classes. As a theory it is best studied as a subsystem of second order number theory, and then the question arises to relate its theoretical strength to other such subsystems. A natural benchmark is the levels of determinacy of Gale-Stewart two person perfect information games it can prove.Robert Recorde Room

Department of Computer Science