מאיר גולדברג

In this work we consider a standard numeral system in the lambda-calculus, and the elementary arithmetic and Boolean functions and predicates defined on this numeral system, and show how to construct terms that "circumvent" or "defeat" these functions: The equality predicate is satisfied when comparing these special terms to any numeral, the zero predicate is satisfied for these terms, etc. We believe this exercise offers an instructive look at what definability means in the untyped lambda-calculus.