Theorem refsymrel3

Description: A relation which is reflexive and symmetric (like an equivalence relation) can use the A. x e. dom R x R x version for its reflexive part, not just the A. x e. dom R A. y e. ran R ( x = y -> x R y ) version of dfrefrel3 , cf. the comment of dfrefrel3 . (Contributed by Peter Mazsa, 23-Aug-2021)

	Ref	Expression
Assertion	refsymrel3	⊢ ( ( RefRel 𝑅 ∧ SymRel 𝑅 ) ↔ ( ( ∀ 𝑥 ∈ dom 𝑅 𝑥 𝑅 𝑥 ∧ ∀ 𝑥 ∀ 𝑦 ( 𝑥 𝑅 𝑦 → 𝑦 𝑅 𝑥 ) ) ∧ Rel 𝑅 ) )

Proof

Step	Hyp	Ref	Expression
1		dfrefrel3	⊢ ( RefRel 𝑅 ↔ ( ∀ 𝑥 ∈ dom 𝑅 ∀ 𝑦 ∈ ran 𝑅 ( 𝑥 = 𝑦 → 𝑥 𝑅 𝑦 ) ∧ Rel 𝑅 ) )
2		dfsymrel3	⊢ ( SymRel 𝑅 ↔ ( ∀ 𝑥 ∀ 𝑦 ( 𝑥 𝑅 𝑦 → 𝑦 𝑅 𝑥 ) ∧ Rel 𝑅 ) )
3	1 2	anbi12i	⊢ ( ( RefRel 𝑅 ∧ SymRel 𝑅 ) ↔ ( ( ∀ 𝑥 ∈ dom 𝑅 ∀ 𝑦 ∈ ran 𝑅 ( 𝑥 = 𝑦 → 𝑥 𝑅 𝑦 ) ∧ Rel 𝑅 ) ∧ ( ∀ 𝑥 ∀ 𝑦 ( 𝑥 𝑅 𝑦 → 𝑦 𝑅 𝑥 ) ∧ Rel 𝑅 ) ) )
4		anandi3r	⊢ ( ( ∀ 𝑥 ∈ dom 𝑅 ∀ 𝑦 ∈ ran 𝑅 ( 𝑥 = 𝑦 → 𝑥 𝑅 𝑦 ) ∧ Rel 𝑅 ∧ ∀ 𝑥 ∀ 𝑦 ( 𝑥 𝑅 𝑦 → 𝑦 𝑅 𝑥 ) ) ↔ ( ( ∀ 𝑥 ∈ dom 𝑅 ∀ 𝑦 ∈ ran 𝑅 ( 𝑥 = 𝑦 → 𝑥 𝑅 𝑦 ) ∧ Rel 𝑅 ) ∧ ( ∀ 𝑥 ∀ 𝑦 ( 𝑥 𝑅 𝑦 → 𝑦 𝑅 𝑥 ) ∧ Rel 𝑅 ) ) )
5		3anan32	⊢ ( ( ∀ 𝑥 ∈ dom 𝑅 ∀ 𝑦 ∈ ran 𝑅 ( 𝑥 = 𝑦 → 𝑥 𝑅 𝑦 ) ∧ Rel 𝑅 ∧ ∀ 𝑥 ∀ 𝑦 ( 𝑥 𝑅 𝑦 → 𝑦 𝑅 𝑥 ) ) ↔ ( ( ∀ 𝑥 ∈ dom 𝑅 ∀ 𝑦 ∈ ran 𝑅 ( 𝑥 = 𝑦 → 𝑥 𝑅 𝑦 ) ∧ ∀ 𝑥 ∀ 𝑦 ( 𝑥 𝑅 𝑦 → 𝑦 𝑅 𝑥 ) ) ∧ Rel 𝑅 ) )
6	3 4 5	3bitr2i	⊢ ( ( RefRel 𝑅 ∧ SymRel 𝑅 ) ↔ ( ( ∀ 𝑥 ∈ dom 𝑅 ∀ 𝑦 ∈ ran 𝑅 ( 𝑥 = 𝑦 → 𝑥 𝑅 𝑦 ) ∧ ∀ 𝑥 ∀ 𝑦 ( 𝑥 𝑅 𝑦 → 𝑦 𝑅 𝑥 ) ) ∧ Rel 𝑅 ) )
7		symrefref3	⊢ ( ∀ 𝑥 ∀ 𝑦 ( 𝑥 𝑅 𝑦 → 𝑦 𝑅 𝑥 ) → ( ∀ 𝑥 ∈ dom 𝑅 ∀ 𝑦 ∈ ran 𝑅 ( 𝑥 = 𝑦 → 𝑥 𝑅 𝑦 ) ↔ ∀ 𝑥 ∈ dom 𝑅 𝑥 𝑅 𝑥 ) )
8	7	pm5.32ri	⊢ ( ( ∀ 𝑥 ∈ dom 𝑅 ∀ 𝑦 ∈ ran 𝑅 ( 𝑥 = 𝑦 → 𝑥 𝑅 𝑦 ) ∧ ∀ 𝑥 ∀ 𝑦 ( 𝑥 𝑅 𝑦 → 𝑦 𝑅 𝑥 ) ) ↔ ( ∀ 𝑥 ∈ dom 𝑅 𝑥 𝑅 𝑥 ∧ ∀ 𝑥 ∀ 𝑦 ( 𝑥 𝑅 𝑦 → 𝑦 𝑅 𝑥 ) ) )
9	8	anbi1i	⊢ ( ( ( ∀ 𝑥 ∈ dom 𝑅 ∀ 𝑦 ∈ ran 𝑅 ( 𝑥 = 𝑦 → 𝑥 𝑅 𝑦 ) ∧ ∀ 𝑥 ∀ 𝑦 ( 𝑥 𝑅 𝑦 → 𝑦 𝑅 𝑥 ) ) ∧ Rel 𝑅 ) ↔ ( ( ∀ 𝑥 ∈ dom 𝑅 𝑥 𝑅 𝑥 ∧ ∀ 𝑥 ∀ 𝑦 ( 𝑥 𝑅 𝑦 → 𝑦 𝑅 𝑥 ) ) ∧ Rel 𝑅 ) )
10	6 9	bitri	⊢ ( ( RefRel 𝑅 ∧ SymRel 𝑅 ) ↔ ( ( ∀ 𝑥 ∈ dom 𝑅 𝑥 𝑅 𝑥 ∧ ∀ 𝑥 ∀ 𝑦 ( 𝑥 𝑅 𝑦 → 𝑦 𝑅 𝑥 ) ) ∧ Rel 𝑅 ) )