lean2/library/logic/axioms/em.lean at 670eac9d5066d9a219d40b33e12aa93bdd4d109d - michael/lean2 - Forgejo: Beyond coding. We forge.

michael/lean2

Leonardo de Moura 6e6cc749a8 feat(library/logic/axioms): break prop_complete into propext and em

The user may want to use propext without assuming em.

2015-03-31 18:51:43 -07:00

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 /-
 Copyright (c) 2015 Microsoft Corporation. All rights reserved.
 Released under Apache 2.0 license as described in the file LICENSE.
 Module: logic.axioms.funext
 Author: Leonardo de Moura
 Excluded middle
 Remark: This axiom can be derived from propext funext and hilbert.
 See examples/diaconescu
 -/
 axiom em (a : Prop) : a ∨ ¬a