Theorem fn0 5203

Description: A function with empty domain is empty. (The proof was shortened by Andrew Salmon, 17-Sep-2011.) (Contributed by set.mm contributors, 15-Apr-1998.) (Revised by set.mm contributors, 18-Sep-2011.)

Assertion

Ref	Expression
fn0	|- (F Fn (/) <-> F = (/))

Proof of Theorem fn0

Step	Hyp	Ref	Expression
1		fndm 5183	. . 3 |- (F Fn (/) -> dom F = (/))
2		dmeq0 4923	. . 3 |- (F = (/) <-> dom F = (/))
3	1, 2	sylibr 203	. 2 |- (F Fn (/) -> F = (/))
4		fun0 5155	. . . 4 |- Fun (/)
5		dm0 4919	. . . 4 |- dom (/) = (/)
6		df-fn 4791	. . . 4 |- ((/) Fn (/) <-> (Fun (/) /\ dom (/) = (/)))
7	4, 5, 6	mpbir2an 886	. . 3 |- (/) Fn (/)
8		fneq1 5174	. . 3 |- (F = (/) -> (F Fn (/) <-> (/) Fn (/)))
9	7, 8	mpbiri 224	. 2 |- (F = (/) -> F Fn (/))
10	3, 9	impbii 180	1 |- (F Fn (/) <-> F = (/))

Syntax hints:   <-> wb 176   = wceq 1642  (/)c0 3551  dom cdm 4773  Fun wfun 4776   Fn wfn 4777

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-cnv 4786  df-rn 4787  df-dm 4788  df-fun 4790  df-fn 4791

This theorem is referenced by:  f00  5250  f1o00  5318  fo00  5319  fconstfv  5457  map0e  6024