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Mirrors > Home > MPE Home > Th. List > 0cat | Structured version Visualization version GIF version |
Description: The empty set is a category, the empty category, see example 3.3(4.c) in [Adamek] p. 24. (Contributed by Mario Carneiro, 3-Jan-2017.) |
Ref | Expression |
---|---|
0cat | ⊢ ∅ ∈ Cat |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 0ex 5210 | . 2 ⊢ ∅ ∈ V | |
2 | base0 16535 | . 2 ⊢ ∅ = (Base‘∅) | |
3 | 0catg 16957 | . 2 ⊢ ((∅ ∈ V ∧ ∅ = (Base‘∅)) → ∅ ∈ Cat) | |
4 | 1, 2, 3 | mp2an 690 | 1 ⊢ ∅ ∈ Cat |
Colors of variables: wff setvar class |
Syntax hints: = wceq 1533 ∈ wcel 2110 Vcvv 3494 ∅c0 4290 ‘cfv 6354 Basecbs 16482 Catccat 16934 |
This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1792 ax-4 1806 ax-5 1907 ax-6 1966 ax-7 2011 ax-8 2112 ax-9 2120 ax-10 2141 ax-11 2157 ax-12 2173 ax-ext 2793 ax-sep 5202 ax-nul 5209 ax-pow 5265 ax-pr 5329 |
This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-3an 1085 df-tru 1536 df-ex 1777 df-nf 1781 df-sb 2066 df-mo 2618 df-eu 2650 df-clab 2800 df-cleq 2814 df-clel 2893 df-nfc 2963 df-ral 3143 df-rex 3144 df-rab 3147 df-v 3496 df-sbc 3772 df-dif 3938 df-un 3940 df-in 3942 df-ss 3951 df-nul 4291 df-if 4467 df-sn 4567 df-pr 4569 df-op 4573 df-uni 4838 df-br 5066 df-opab 5128 df-mpt 5146 df-id 5459 df-xp 5560 df-rel 5561 df-cnv 5562 df-co 5563 df-dm 5564 df-iota 6313 df-fun 6356 df-fv 6362 df-ov 7158 df-slot 16486 df-base 16488 df-cat 16938 |
This theorem is referenced by: (None) |
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