Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with
Search options not deleted user 38527
2 votes

Why in Martin-Löf type theory any natural number is assumed to be either $0$ or $S(a)$ for s...

First, we should pin down that we're talking about closed terms with natural number type, that is, terms without free variables. A free variable with type $\mathsf{N}$ is clearly not of the form $0$ o …
András Kovács's user avatar
8 votes
Accepted

Is $\prod_{X : \mathcal{U}} (X \to X) \cong 1$ consistent with type theory?

$\prod_{X : \mathcal{U}} (X \to X) \cong 1$ is consistent. It follows from parametricity and function extensionality. Usual parametric models also support function extensionality. The simplest one whi …
András Kovács's user avatar