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Questions about higher-order logic, that is logic that allows arbitrary quantification, e.g. over sets of functions.
computability and complexity in real or complex analysis
Church numerals are an encoding of integers in the lambda calculus
Meta-programming is the writing of programs with the ability to treat programs as their data.
Isabelle is an interactive theorem prover, mostly used as Isabelle/HOL which is based on higer-order logic
A doubly-connected edge list (DCEL) is an edge-centered data structure capable of maintaining incidence information of vertices, edges and faces, for example for planar maps.