Theorem fconstg 5252

Description: A cross product with a singleton is a constant function. (Contributed by set.mm contributors, 19-Oct-2004.)

Assertion

Ref	Expression
fconstg	⊢ (B ∈ V → (A × {B}):A–→{B})

Proof of Theorem fconstg

Dummy variable x is distinct from all other variables.

Step	Hyp	Ref	Expression
1		sneq 3745	. . . 4 ⊢ (x = B → {x} = {B})
2	1	xpeq2d 4809	. . 3 ⊢ (x = B → (A × {x}) = (A × {B}))
3		feq1 5211	. . . 4 ⊢ ((A × {x}) = (A × {B}) → ((A × {x}):A–→{x} ↔ (A × {B}):A–→{x}))
4		feq3 5213	. . . 4 ⊢ ({x} = {B} → ((A × {B}):A–→{x} ↔ (A × {B}):A–→{B}))
5	3, 4	sylan9bb 680	. . 3 ⊢ (((A × {x}) = (A × {B}) ∧ {x} = {B}) → ((A × {x}):A–→{x} ↔ (A × {B}):A–→{B}))
6	2, 1, 5	syl2anc 642	. 2 ⊢ (x = B → ((A × {x}):A–→{x} ↔ (A × {B}):A–→{B}))
7		vex 2863	. . 3 ⊢ x ∈ V
8	7	fconst 5251	. 2 ⊢ (A × {x}):A–→{x}
9	6, 8	vtoclg 2915	1 ⊢ (B ∈ V → (A × {B}):A–→{B})

Syntax hints:   → wi 4   ↔ wb 176   = wceq 1642   ∈ wcel 1710  {csn 3738   × cxp 4771  –→wf 4778

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-co 4727  df-ima 4728  df-id 4768  df-xp 4785  df-cnv 4786  df-rn 4787  df-dm 4788  df-fun 4790  df-fn 4791  df-f 4792

This theorem is referenced by:  fnconstg  5253  fvconst2g  5452  fconst2g  5453