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Theorem 0g0 17530
Description: The identity element function evaluates to the empty set on an empty structure. (Contributed by Stefan O'Rear, 2-Oct-2015.)
Assertion
Ref Expression
0g0 ∅ = (0g‘∅)

Proof of Theorem 0g0
Dummy variables 𝑒 𝑥 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 base0 16185 . . 3 ∅ = (Base‘∅)
2 eqid 2764 . . 3 (+g‘∅) = (+g‘∅)
3 eqid 2764 . . 3 (0g‘∅) = (0g‘∅)
41, 2, 3grpidval 17527 . 2 (0g‘∅) = (℩𝑒(𝑒 ∈ ∅ ∧ ∀𝑥 ∈ ∅ ((𝑒(+g‘∅)𝑥) = 𝑥 ∧ (𝑥(+g‘∅)𝑒) = 𝑥)))
5 noel 4082 . . . . . 6 ¬ 𝑒 ∈ ∅
65intnanr 481 . . . . 5 ¬ (𝑒 ∈ ∅ ∧ ∀𝑥 ∈ ∅ ((𝑒(+g‘∅)𝑥) = 𝑥 ∧ (𝑥(+g‘∅)𝑒) = 𝑥))
76nex 1895 . . . 4 ¬ ∃𝑒(𝑒 ∈ ∅ ∧ ∀𝑥 ∈ ∅ ((𝑒(+g‘∅)𝑥) = 𝑥 ∧ (𝑥(+g‘∅)𝑒) = 𝑥))
8 euex 2590 . . . 4 (∃!𝑒(𝑒 ∈ ∅ ∧ ∀𝑥 ∈ ∅ ((𝑒(+g‘∅)𝑥) = 𝑥 ∧ (𝑥(+g‘∅)𝑒) = 𝑥)) → ∃𝑒(𝑒 ∈ ∅ ∧ ∀𝑥 ∈ ∅ ((𝑒(+g‘∅)𝑥) = 𝑥 ∧ (𝑥(+g‘∅)𝑒) = 𝑥)))
97, 8mto 188 . . 3 ¬ ∃!𝑒(𝑒 ∈ ∅ ∧ ∀𝑥 ∈ ∅ ((𝑒(+g‘∅)𝑥) = 𝑥 ∧ (𝑥(+g‘∅)𝑒) = 𝑥))
10 iotanul 6045 . . 3 (¬ ∃!𝑒(𝑒 ∈ ∅ ∧ ∀𝑥 ∈ ∅ ((𝑒(+g‘∅)𝑥) = 𝑥 ∧ (𝑥(+g‘∅)𝑒) = 𝑥)) → (℩𝑒(𝑒 ∈ ∅ ∧ ∀𝑥 ∈ ∅ ((𝑒(+g‘∅)𝑥) = 𝑥 ∧ (𝑥(+g‘∅)𝑒) = 𝑥))) = ∅)
119, 10ax-mp 5 . 2 (℩𝑒(𝑒 ∈ ∅ ∧ ∀𝑥 ∈ ∅ ((𝑒(+g‘∅)𝑥) = 𝑥 ∧ (𝑥(+g‘∅)𝑒) = 𝑥))) = ∅
124, 11eqtr2i 2787 1 ∅ = (0g‘∅)
Colors of variables: wff setvar class
Syntax hints:  ¬ wn 3  wa 384   = wceq 1652  wex 1874  wcel 2155  ∃!weu 2580  wral 3054  c0 4078  cio 6028  cfv 6067  (class class class)co 6841  +gcplusg 16215  0gc0g 16367
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1890  ax-4 1904  ax-5 2005  ax-6 2069  ax-7 2105  ax-8 2157  ax-9 2164  ax-10 2183  ax-11 2198  ax-12 2211  ax-13 2349  ax-ext 2742  ax-sep 4940  ax-nul 4948  ax-pow 5000  ax-pr 5061
This theorem depends on definitions:  df-bi 198  df-an 385  df-or 874  df-3an 1109  df-tru 1656  df-ex 1875  df-nf 1879  df-sb 2062  df-mo 2564  df-eu 2581  df-clab 2751  df-cleq 2757  df-clel 2760  df-nfc 2895  df-ral 3059  df-rex 3060  df-rab 3063  df-v 3351  df-sbc 3596  df-dif 3734  df-un 3736  df-in 3738  df-ss 3745  df-nul 4079  df-if 4243  df-sn 4334  df-pr 4336  df-op 4340  df-uni 4594  df-br 4809  df-opab 4871  df-mpt 4888  df-id 5184  df-xp 5282  df-rel 5283  df-cnv 5284  df-co 5285  df-dm 5286  df-iota 6030  df-fun 6069  df-fv 6075  df-ov 6844  df-slot 16135  df-base 16137  df-0g 16369
This theorem is referenced by:  frmd0  17665  ringidval  18769
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