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Theorem grpinvnz 18973
Description: The inverse of a nonzero group element is not zero. (Contributed by Stefan O'Rear, 27-Feb-2015.)
Hypotheses
Ref Expression
grpinvnzcl.b 𝐵 = (Base‘𝐺)
grpinvnzcl.z 0 = (0g𝐺)
grpinvnzcl.n 𝑁 = (invg𝐺)
Assertion
Ref Expression
grpinvnz ((𝐺 ∈ Grp ∧ 𝑋𝐵𝑋0 ) → (𝑁𝑋) ≠ 0 )

Proof of Theorem grpinvnz
StepHypRef Expression
1 fveq2 6902 . . . . . 6 ((𝑁𝑋) = 0 → (𝑁‘(𝑁𝑋)) = (𝑁0 ))
21adantl 480 . . . . 5 (((𝐺 ∈ Grp ∧ 𝑋𝐵) ∧ (𝑁𝑋) = 0 ) → (𝑁‘(𝑁𝑋)) = (𝑁0 ))
3 grpinvnzcl.b . . . . . . 7 𝐵 = (Base‘𝐺)
4 grpinvnzcl.n . . . . . . 7 𝑁 = (invg𝐺)
53, 4grpinvinv 18969 . . . . . 6 ((𝐺 ∈ Grp ∧ 𝑋𝐵) → (𝑁‘(𝑁𝑋)) = 𝑋)
65adantr 479 . . . . 5 (((𝐺 ∈ Grp ∧ 𝑋𝐵) ∧ (𝑁𝑋) = 0 ) → (𝑁‘(𝑁𝑋)) = 𝑋)
7 grpinvnzcl.z . . . . . . 7 0 = (0g𝐺)
87, 4grpinvid 18963 . . . . . 6 (𝐺 ∈ Grp → (𝑁0 ) = 0 )
98ad2antrr 724 . . . . 5 (((𝐺 ∈ Grp ∧ 𝑋𝐵) ∧ (𝑁𝑋) = 0 ) → (𝑁0 ) = 0 )
102, 6, 93eqtr3d 2776 . . . 4 (((𝐺 ∈ Grp ∧ 𝑋𝐵) ∧ (𝑁𝑋) = 0 ) → 𝑋 = 0 )
1110ex 411 . . 3 ((𝐺 ∈ Grp ∧ 𝑋𝐵) → ((𝑁𝑋) = 0𝑋 = 0 ))
1211necon3d 2958 . 2 ((𝐺 ∈ Grp ∧ 𝑋𝐵) → (𝑋0 → (𝑁𝑋) ≠ 0 ))
13123impia 1114 1 ((𝐺 ∈ Grp ∧ 𝑋𝐵𝑋0 ) → (𝑁𝑋) ≠ 0 )
Colors of variables: wff setvar class
Syntax hints:  wi 4  wa 394  w3a 1084   = wceq 1533  wcel 2098  wne 2937  cfv 6553  Basecbs 17187  0gc0g 17428  Grpcgrp 18897  invgcminusg 18898
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1789  ax-4 1803  ax-5 1905  ax-6 1963  ax-7 2003  ax-8 2100  ax-9 2108  ax-10 2129  ax-11 2146  ax-12 2166  ax-ext 2699  ax-sep 5303  ax-nul 5310  ax-pow 5369  ax-pr 5433  ax-un 7746
This theorem depends on definitions:  df-bi 206  df-an 395  df-or 846  df-3an 1086  df-tru 1536  df-fal 1546  df-ex 1774  df-nf 1778  df-sb 2060  df-mo 2529  df-eu 2558  df-clab 2706  df-cleq 2720  df-clel 2806  df-nfc 2881  df-ne 2938  df-ral 3059  df-rex 3068  df-rmo 3374  df-reu 3375  df-rab 3431  df-v 3475  df-sbc 3779  df-dif 3952  df-un 3954  df-in 3956  df-ss 3966  df-nul 4327  df-if 4533  df-pw 4608  df-sn 4633  df-pr 4635  df-op 4639  df-uni 4913  df-br 5153  df-opab 5215  df-mpt 5236  df-id 5580  df-xp 5688  df-rel 5689  df-cnv 5690  df-co 5691  df-dm 5692  df-rn 5693  df-res 5694  df-ima 5695  df-iota 6505  df-fun 6555  df-fn 6556  df-f 6557  df-fv 6561  df-riota 7382  df-ov 7429  df-0g 17430  df-mgm 18607  df-sgrp 18686  df-mnd 18702  df-grp 18900  df-minusg 18901
This theorem is referenced by:  grpinvnzcl  18974
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