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The Type Theory of Lean

Mario Carneiro

cs.LO Jan 1, 2020 · v1
Provides a formal specification of Lean's kernel type theory and metatheoretic properties.
This master's thesis describes the type theory underlying the Lean theorem prover, providing a formal specification of the calculus of inductive constructions as implemented in Lean. It covers the kernel type system, soundness, and normalization properties of the system.

The Lean theorem prover needs a rigorous formal specification of its underlying type theory to establish trust in its kernel and enable independent verification of its soundness.

This master's thesis describes the type theory underlying the Lean theorem prover, providing a formal specification of the calculus of inductive constructions as implemented in Lean. It covers the kernel type system, soundness, and normalization properties.

The thesis provides a complete formal specification of Lean's type theory, covering inductive types, universes, and reduction rules, serving as a reference for the system's metatheoretic properties.