Update formal.tex

Typo
Merge pull request #709 from spearman/patch-1

Fix typo in appendix
Updated some Punctuation problems.

In English Punctuation is important for your texts, because when I see a post which have a Punctuation problem, I will never read it, and most of the people will ignore it. It's the psychology of human.

You should put comma before which
it's utility instead of utlity
Punctuation is important in the text.

Punctuation is important in the text.

I fixed 2 Punctuation problems.
Change the induction principle of V
Merge pull request #710 from araratm/master

Updated some Punctuation problems.
Merge pull request #711 from araratm/patch-1

Punctuation is important in the text.
re-fix some grammar
Package 'mh' no longer exists, so get 'mathtools' for travis instead
Merge pull request #714 from mikeshulman/grammar

re-fix some grammar
Merge pull request #715 from mikeshulman/travis

Package 'mh' no longer exists, so get 'mathtools' for travis instead
fix an ambiguous sentence
Fix a type

Arguably a better fix for #716.
Merge pull request #717 from kirelagin/patch-4

Fix a type
rephrase Remark 1.5.1 without counting, close #720
Merge pull request #721 from mikeshulman/remark1.5.1

rephrase Remark 1.5.1 without counting, close #720
Merge pull request #712 from jledent/master

Change the induction principle of V
introduced macro for uniq
changed rule name macros
renamed the uniqueness principles of products, unit and named the uniqueness principle of dependent pair types