[Agda] excluded-middle

[Thorsten Altenkirch]

Excluded middle should only apply to propositions, where a proposition is a type with at most one inhabitant.

Otherwise it is much stronger because it chooses an element in each inhabited set and incompatible with univalence (I think).

Thorsten



On 22/06/2016, 09:10, "agda-bounces at lists.chalmers.se on behalf of Nils Anders Danielsson" <agda-bounces at lists.chalmers.se on behalf of nad at cse.gu.se> wrote:

>On 2016-06-22 03:59, Katsutoshi Itoh wrote:
>> 3. double negate elimination is valid in the logic
>
>No, it's not.
>
>> I've beleave dne and em are the same thing, but 2 and 3 suggest dne
>> and em are NOT.
>
>The standard library module Relation.Nullary.Negation contains proofs
>showing that excluded middle and double-negation elimination are
>logically equivalent.
>
>-- 
>/NAD
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