elrelscnveq3 - Mathbox for Peter Mazsa

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Theorem elrelscnveq3 38948

Description: Two ways of saying a relation is symmetric. (Contributed by Peter Mazsa, 22-Aug-2021.)

**Assertion**
Ref	Expression
elrelscnveq3	⊢ (𝑅 ∈ Rels → (𝑅 = ^◡𝑅 ↔ ∀𝑥∀𝑦(𝑥𝑅𝑦 → 𝑦𝑅𝑥)))

Distinct variable group: 𝑥,𝑅,𝑦

**Proof of Theorem elrelscnveq3**
Step	Hyp	Ref	Expression
1		eqss 3937	. 2 ⊢ (𝑅 = ^◡𝑅 ↔ (𝑅 ⊆ ^◡𝑅 ∧ ^◡𝑅 ⊆ 𝑅))
2		cnvsym 6077	. . . . . . 7 ⊢ (^◡𝑅 ⊆ 𝑅 ↔ ∀𝑥∀𝑦(𝑥𝑅𝑦 → 𝑦𝑅𝑥))
3	2	biimpi 216	. . . . . 6 ⊢ (^◡𝑅 ⊆ 𝑅 → ∀𝑥∀𝑦(𝑥𝑅𝑦 → 𝑦𝑅𝑥))
4	3	a1d 25	. . . . 5 ⊢ (^◡𝑅 ⊆ 𝑅 → (𝑅 ∈ Rels → ∀𝑥∀𝑦(𝑥𝑅𝑦 → 𝑦𝑅𝑥)))
5	4	adantl 481	. . . 4 ⊢ ((𝑅 ⊆ ^◡𝑅 ∧ ^◡𝑅 ⊆ 𝑅) → (𝑅 ∈ Rels → ∀𝑥∀𝑦(𝑥𝑅𝑦 → 𝑦𝑅𝑥)))
6	5	com12 32	. . 3 ⊢ (𝑅 ∈ Rels → ((𝑅 ⊆ ^◡𝑅 ∧ ^◡𝑅 ⊆ 𝑅) → ∀𝑥∀𝑦(𝑥𝑅𝑦 → 𝑦𝑅𝑥)))
7		elrelsrelim 38764	. . . . . 6 ⊢ (𝑅 ∈ Rels → Rel 𝑅)
8		dfrel2 6153	. . . . . 6 ⊢ (Rel 𝑅 ↔ ^◡^◡𝑅 = 𝑅)
9	7, 8	sylib 218	. . . . 5 ⊢ (𝑅 ∈ Rels → ^◡^◡𝑅 = 𝑅)
10		cnvss 5827	. . . . . . 7 ⊢ (^◡𝑅 ⊆ 𝑅 → ^◡^◡𝑅 ⊆ ^◡𝑅)
11		sseq1 3947	. . . . . . 7 ⊢ (^◡^◡𝑅 = 𝑅 → (^◡^◡𝑅 ⊆ ^◡𝑅 ↔ 𝑅 ⊆ ^◡𝑅))
12	10, 11	syl5ibcom 245	. . . . . 6 ⊢ (^◡𝑅 ⊆ 𝑅 → (^◡^◡𝑅 = 𝑅 → 𝑅 ⊆ ^◡𝑅))
13	2, 12	sylbir 235	. . . . 5 ⊢ (∀𝑥∀𝑦(𝑥𝑅𝑦 → 𝑦𝑅𝑥) → (^◡^◡𝑅 = 𝑅 → 𝑅 ⊆ ^◡𝑅))
14	9, 13	syl5com 31	. . . 4 ⊢ (𝑅 ∈ Rels → (∀𝑥∀𝑦(𝑥𝑅𝑦 → 𝑦𝑅𝑥) → 𝑅 ⊆ ^◡𝑅))
15	2	biimpri 228	. . . 4 ⊢ (∀𝑥∀𝑦(𝑥𝑅𝑦 → 𝑦𝑅𝑥) → ^◡𝑅 ⊆ 𝑅)
16	14, 15	jca2 513	. . 3 ⊢ (𝑅 ∈ Rels → (∀𝑥∀𝑦(𝑥𝑅𝑦 → 𝑦𝑅𝑥) → (𝑅 ⊆ ^◡𝑅 ∧ ^◡𝑅 ⊆ 𝑅)))
17	6, 16	impbid 212	. 2 ⊢ (𝑅 ∈ Rels → ((𝑅 ⊆ ^◡𝑅 ∧ ^◡𝑅 ⊆ 𝑅) ↔ ∀𝑥∀𝑦(𝑥𝑅𝑦 → 𝑦𝑅𝑥)))
18	1, 17	bitrid 283	1 ⊢ (𝑅 ∈ Rels → (𝑅 = ^◡𝑅 ↔ ∀𝑥∀𝑦(𝑥𝑅𝑦 → 𝑦𝑅𝑥)))

Colors of variables: wff setvar class

Syntax hints: → wi 4 ↔ wb 206 ∧ wa 395 ∀wal 1540 = wceq 1542 ∈ wcel 2114 ⊆ wss 3889 class class class wbr 5085 ^◡ccnv 5630 Rel wrel 5636 Rels crels 38506

This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1797 ax-4 1811 ax-5 1912 ax-6 1969 ax-7 2010 ax-8 2116 ax-9 2124 ax-ext 2708 ax-sep 5231 ax-pr 5375

This theorem depends on definitions: df-bi 207 df-an 396 df-or 849 df-3an 1089 df-tru 1545 df-fal 1555 df-ex 1782 df-sb 2069 df-clab 2715 df-cleq 2728 df-clel 2811 df-rab 3390 df-v 3431 df-dif 3892 df-un 3894 df-in 3896 df-ss 3906 df-nul 4274 df-if 4467 df-pw 4543 df-sn 4568 df-pr 4570 df-op 4574 df-br 5086 df-opab 5148 df-xp 5637 df-rel 5638 df-cnv 5639 df-rels 38761

This theorem is referenced by: elrelscnveq 38949

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