* 3.4

* More 3.4

* More 3.4

* More 3.4

* More 3.4

* More 3.4

* More 3.4

* More 3.4

* More 3.4

* More 3.4

* More 3.4

* More 3.4

* More 3.4

* Golf

* Some 2-epilogue problems

* More 2-epilogue

* More 2-epilogue

* More solutions

* More solutions

* More solutions

* Hell yeah

* Section 2.3 solutions

* More 2.3

* More section 2.3

* Comment

* Some section 2.2 solutions

* More Section 2.2 solutions

Fill in SetTheory.Set.iProd_equiv_pi

change a to x; add comment

fix gap in 3.1

fix gap in proof in Sec 11.4

fix bug caused by ext change

tag extensionality as @[ext] in section 3.1 to allow the `ext` tactic to work

Fill in some of 3.5, fix numbering

a little more golf

null

Disable wavy red underline for errors

Fill in a bit of SetTheory.Set.prod_equiv_prod

Add equality lemma for mk_cartesian

more golf

golf

Add a helper lemma for Exercise 3.5.1

Fixing a broken link in the README

Add some missing exercises in Ch3.6

Remove unused junk variables

fix a proof due to swapped order

remove a simp lemma and swap an equality

more golf