lean2/library/data/countable.lean

/-
Copyright (c) 2015 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.
Author: Leonardo de Moura

Define countable types
-/
import algebra.function
open function

definition countable (A : Type) : Prop := ∃ f : A → nat, injective f
chore(library/data/countable): add copyright notice 2015-04-16 16:24:53 +00:00			`/-`
			`Copyright (c) 2015 Microsoft Corporation. All rights reserved.`
			`Released under Apache 2.0 license as described in the file LICENSE.`
			`Author: Leonardo de Moura`

refactor(library/data): rename 'countable' to 'encodable', define countable in the usual way, and prove all 'encodable' type is 'countable' 2015-04-19 21:18:49 +00:00			`Define countable types`
chore(library/data/countable): add copyright notice 2015-04-16 16:24:53 +00:00			`-/`
refactor(library/data): rename 'countable' to 'encodable', define countable in the usual way, and prove all 'encodable' type is 'countable' 2015-04-19 21:18:49 +00:00			`import algebra.function`
			`open function`
feat(library/data/countable): define countable type class 2015-04-13 15:09:23 +00:00
refactor(library/data): rename 'countable' to 'encodable', define countable in the usual way, and prove all 'encodable' type is 'countable' 2015-04-19 21:18:49 +00:00			`definition countable (A : Type) : Prop := ∃ f : A → nat, injective f`