Theorem br2nd 4860

Description: Binary relationship equivalence for the 2^nd function. (Contributed by set.mm contributors, 8-Jan-2015.)

Hypothesis

Ref	Expression
br1st.1	⊢ B ∈ V

Assertion

Ref	Expression
br2nd	⊢ (A2nd B ↔ ∃x A = ⟨x, B⟩)

Distinct variable groups:   x,A   x,B

Proof of Theorem br2nd

Dummy variables y z are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		brex 4690	. . 3 ⊢ (A2nd B → (A ∈ V ∧ B ∈ V))
2	1	simpld 445	. 2 ⊢ (A2nd B → A ∈ V)
3		vex 2863	. . . . 5 ⊢ x ∈ V
4		br1st.1	. . . . 5 ⊢ B ∈ V
5	3, 4	opex 4589	. . . 4 ⊢ ⟨x, B⟩ ∈ V
6		eleq1 2413	. . . 4 ⊢ (A = ⟨x, B⟩ → (A ∈ V ↔ ⟨x, B⟩ ∈ V))
7	5, 6	mpbiri 224	. . 3 ⊢ (A = ⟨x, B⟩ → A ∈ V)
8	7	exlimiv 1634	. 2 ⊢ (∃x A = ⟨x, B⟩ → A ∈ V)
9		eqeq1 2359	. . . . 5 ⊢ (y = A → (y = ⟨x, z⟩ ↔ A = ⟨x, z⟩))
10	9	exbidv 1626	. . . 4 ⊢ (y = A → (∃x y = ⟨x, z⟩ ↔ ∃x A = ⟨x, z⟩))
11		opeq2 4580	. . . . . 6 ⊢ (z = B → ⟨x, z⟩ = ⟨x, B⟩)
12	11	eqeq2d 2364	. . . . 5 ⊢ (z = B → (A = ⟨x, z⟩ ↔ A = ⟨x, B⟩))
13	12	exbidv 1626	. . . 4 ⊢ (z = B → (∃x A = ⟨x, z⟩ ↔ ∃x A = ⟨x, B⟩))
14		df-2nd 4798	. . . 4 ⊢ 2nd = {⟨y, z⟩ ∣ ∃x y = ⟨x, z⟩}
15	10, 13, 14	brabg 4707	. . 3 ⊢ ((A ∈ V ∧ B ∈ V) → (A2nd B ↔ ∃x A = ⟨x, B⟩))
16	4, 15	mpan2 652	. 2 ⊢ (A ∈ V → (A2nd B ↔ ∃x A = ⟨x, B⟩))
17	2, 8, 16	pm5.21nii 342	1 ⊢ (A2nd B ↔ ∃x A = ⟨x, B⟩)

Syntax hints:   ↔ wb 176  ∃wex 1541   = wceq 1642   ∈ wcel 1710  Vcvv 2860  ⟨cop 4562   class class class wbr 4640  2^nd c2nd 4784

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1546  ax-5 1557  ax-17 1616  ax-9 1654  ax-8 1675  ax-13 1712  ax-14 1714  ax-6 1729  ax-7 1734  ax-11 1746  ax-12 1925  ax-ext 2334  ax-nin 4079  ax-xp 4080  ax-cnv 4081  ax-1c 4082  ax-sset 4083  ax-si 4084  ax-ins2 4085  ax-ins3 4086  ax-typlower 4087  ax-sn 4088

This theorem depends on definitions:  df-bi 177  df-or 359  df-an 360  df-3or 935  df-3an 936  df-nan 1288  df-tru 1319  df-ex 1542  df-nf 1545  df-sb 1649  df-eu 2208  df-mo 2209  df-clab 2340  df-cleq 2346  df-clel 2349  df-nfc 2479  df-ne 2519  df-ral 2620  df-rex 2621  df-reu 2622  df-rmo 2623  df-rab 2624  df-v 2862  df-sbc 3048  df-nin 3212  df-compl 3213  df-in 3214  df-un 3215  df-dif 3216  df-symdif 3217  df-ss 3260  df-pss 3262  df-nul 3552  df-if 3664  df-pw 3725  df-sn 3742  df-pr 3743  df-uni 3893  df-int 3928  df-opk 4059  df-1c 4137  df-pw1 4138  df-uni1 4139  df-xpk 4186  df-cnvk 4187  df-ins2k 4188  df-ins3k 4189  df-imak 4190  df-cok 4191  df-p6 4192  df-sik 4193  df-ssetk 4194  df-imagek 4195  df-idk 4196  df-iota 4340  df-0c 4378  df-addc 4379  df-nnc 4380  df-fin 4381  df-lefin 4441  df-ltfin 4442  df-ncfin 4443  df-tfin 4444  df-evenfin 4445  df-oddfin 4446  df-sfin 4447  df-spfin 4448  df-phi 4566  df-op 4567  df-proj1 4568  df-proj2 4569  df-opab 4624  df-br 4641  df-2nd 4798

This theorem is referenced by:  dfxp2  5114  opbr2nd  5503  2ndfo  5507  dfrn5  5509  brtxp  5784