Metamath Proof Explorer


Theorem dfsymrels5

Description: Alternate definition of the class of symmetric relations. (Contributed by Peter Mazsa, 22-Jul-2021)

Ref Expression
Assertion dfsymrels5 SymRels = { 𝑟 ∈ Rels ∣ ∀ 𝑥𝑦 ( 𝑥 𝑟 𝑦𝑦 𝑟 𝑥 ) }

Proof

Step Hyp Ref Expression
1 dfsymrels4 SymRels = { 𝑟 ∈ Rels ∣ 𝑟 = 𝑟 }
2 elrelscnveq2 ( 𝑟 ∈ Rels → ( 𝑟 = 𝑟 ↔ ∀ 𝑥𝑦 ( 𝑥 𝑟 𝑦𝑦 𝑟 𝑥 ) ) )
3 1 2 rabimbieq SymRels = { 𝑟 ∈ Rels ∣ ∀ 𝑥𝑦 ( 𝑥 𝑟 𝑦𝑦 𝑟 𝑥 ) }