Reminiscences of logicians.- Frames and models in modal logic.- A language and axioms for explicit mathematics.- Dimension theory of commutative polynomial rings.- Dimension theory of power series rings over a commutative ring.- Axiomatic classes in propositional modal logic.- Nilpotent actions on nilpotent groups.- Structure theorems for inverse semigroups.- Recursion theory and algebra.- An exposition of forcing.- Logic and foundations.- Church-Rosser theorems for replacement systems.