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Theorem 0g0 17310
 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 15959 . . 3 ∅ = (Base‘∅)
2 eqid 2651 . . 3 (+g‘∅) = (+g‘∅)
3 eqid 2651 . . 3 (0g‘∅) = (0g‘∅)
41, 2, 3grpidval 17307 . 2 (0g‘∅) = (℩𝑒(𝑒 ∈ ∅ ∧ ∀𝑥 ∈ ∅ ((𝑒(+g‘∅)𝑥) = 𝑥 ∧ (𝑥(+g‘∅)𝑒) = 𝑥)))
5 noel 3952 . . . . . 6 ¬ 𝑒 ∈ ∅
65intnanr 981 . . . . 5 ¬ (𝑒 ∈ ∅ ∧ ∀𝑥 ∈ ∅ ((𝑒(+g‘∅)𝑥) = 𝑥 ∧ (𝑥(+g‘∅)𝑒) = 𝑥))
76nex 1771 . . . 4 ¬ ∃𝑒(𝑒 ∈ ∅ ∧ ∀𝑥 ∈ ∅ ((𝑒(+g‘∅)𝑥) = 𝑥 ∧ (𝑥(+g‘∅)𝑒) = 𝑥))
8 euex 2522 . . . 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 5904 . . 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 2674 1 ∅ = (0g‘∅)
 Colors of variables: wff setvar class Syntax hints:  ¬ wn 3   ∧ wa 383   = wceq 1523  ∃wex 1744   ∈ wcel 2030  ∃!weu 2498  ∀wral 2941  ∅c0 3948  ℩cio 5887  ‘cfv 5926  (class class class)co 6690  +gcplusg 15988  0gc0g 16147 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1762  ax-4 1777  ax-5 1879  ax-6 1945  ax-7 1981  ax-8 2032  ax-9 2039  ax-10 2059  ax-11 2074  ax-12 2087  ax-13 2282  ax-ext 2631  ax-sep 4814  ax-nul 4822  ax-pow 4873  ax-pr 4936 This theorem depends on definitions:  df-bi 197  df-or 384  df-an 385  df-3an 1056  df-tru 1526  df-ex 1745  df-nf 1750  df-sb 1938  df-eu 2502  df-mo 2503  df-clab 2638  df-cleq 2644  df-clel 2647  df-nfc 2782  df-ral 2946  df-rex 2947  df-rab 2950  df-v 3233  df-sbc 3469  df-dif 3610  df-un 3612  df-in 3614  df-ss 3621  df-nul 3949  df-if 4120  df-sn 4211  df-pr 4213  df-op 4217  df-uni 4469  df-br 4686  df-opab 4746  df-mpt 4763  df-id 5053  df-xp 5149  df-rel 5150  df-cnv 5151  df-co 5152  df-dm 5153  df-iota 5889  df-fun 5928  df-fv 5934  df-ov 6693  df-slot 15908  df-base 15910  df-0g 16149 This theorem is referenced by:  frmd0  17444  ringidval  18549
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