Metamath Proof Explorer


Definition df-comlaw

Description: The commutative law for binary operations, see definitions of laws A2. and M2. in section 1.1 of Hall p. 1, or definition 8 in BourbakiAlg1 p. 7: the value of a binary operation applied to two operands equals the value of a binary operation applied to the two operands in reversed order. By this definition, the commutative law is expressed as binary relation: a binary operation is related to a set by comLaw if the commutative law holds for this binary operation regarding this set. Note that the binary operation needs neither to be closed nor to be a function. (Contributed by AV, 7-Jan-2020)

Ref Expression
Assertion df-comlaw comLaw = { ⟨ 𝑜 , 𝑚 ⟩ ∣ ∀ 𝑥𝑚𝑦𝑚 ( 𝑥 𝑜 𝑦 ) = ( 𝑦 𝑜 𝑥 ) }

Detailed syntax breakdown

Step Hyp Ref Expression
0 ccomlaw comLaw
1 vo 𝑜
2 vm 𝑚
3 vx 𝑥
4 2 cv 𝑚
5 vy 𝑦
6 3 cv 𝑥
7 1 cv 𝑜
8 5 cv 𝑦
9 6 8 7 co ( 𝑥 𝑜 𝑦 )
10 8 6 7 co ( 𝑦 𝑜 𝑥 )
11 9 10 wceq ( 𝑥 𝑜 𝑦 ) = ( 𝑦 𝑜 𝑥 )
12 11 5 4 wral 𝑦𝑚 ( 𝑥 𝑜 𝑦 ) = ( 𝑦 𝑜 𝑥 )
13 12 3 4 wral 𝑥𝑚𝑦𝑚 ( 𝑥 𝑜 𝑦 ) = ( 𝑦 𝑜 𝑥 )
14 13 1 2 copab { ⟨ 𝑜 , 𝑚 ⟩ ∣ ∀ 𝑥𝑚𝑦𝑚 ( 𝑥 𝑜 𝑦 ) = ( 𝑦 𝑜 𝑥 ) }
15 0 14 wceq comLaw = { ⟨ 𝑜 , 𝑚 ⟩ ∣ ∀ 𝑥𝑚𝑦𝑚 ( 𝑥 𝑜 𝑦 ) = ( 𝑦 𝑜 𝑥 ) }