Database
SUPPLEMENTARY MATERIAL (USERS' MATHBOXES)
Mathbox for Alexander van der Vekens
Even and odd numbers
Definitions and basic properties
oddz
Next ⟩
evendiv2z
Metamath Proof Explorer
Ascii
Structured
Theorem
oddz
Description:
An odd number is an integer.
(Contributed by
AV
, 14-Jun-2020)
Ref
Expression
Assertion
oddz
⊢
(
𝑍
∈ Odd →
𝑍
∈ ℤ )
Proof
Step
Hyp
Ref
Expression
1
isodd
⊢
(
𝑍
∈ Odd ↔ (
𝑍
∈ ℤ ∧ ( (
𝑍
+ 1 ) / 2 ) ∈ ℤ ) )
2
1
simplbi
⊢
(
𝑍
∈ Odd →
𝑍
∈ ℤ )