Problem 3

LCS, page 163: Exercise 2.4.6.

For LEANĻĀ exercises in this assignment, your solutions should be restricted to

tactics and lemmas which are introduced up to the end of [MoP, Section 6.1).

We will take off points from solutions that use tactics and lemmas introduced in

[MoP, Section 6.2] and later sections or nowhere used in [MoP].

In your solutions for Problem 4 and Problem 5 as LEAN 4 scripts, you may want to include the

following imports from the LEAN-4 library (possibly not all of them, but you will have to experiment

to find out if all are needed):

import Mathlib.Data.Real Basic

isport Library Theory Parity

isport Library. Tactic. Induction

isport Library. Tactic ModCases

isport Library. Tactic Extra

isport Library. Tactic Numbers

isport Library. Tactic Addarith

isport Library. Tactic. Use