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Description: Two simple pseudographs are not isomorphic if one has a cycle and the other has no cycle of the same length. (Contributed by AV, 6-Nov-2025)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | cycldlenngric | |- ( ( G e. USPGraph /\ H e. USPGraph ) -> ( ( E. p E. f ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) /\ -. E. p E. f ( f ( Cycles ` H ) p /\ ( # ` f ) = N ) ) -> -. G ~=gr H ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | brgric | |- ( G ~=gr H <-> ( G GraphIso H ) =/= (/) ) |
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| 2 | n0rex | |- ( ( G GraphIso H ) =/= (/) -> E. i e. ( G GraphIso H ) i e. ( G GraphIso H ) ) |
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| 3 | eqid | |- ( iEdg ` G ) = ( iEdg ` G ) |
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| 4 | eqid | |- ( iEdg ` H ) = ( iEdg ` H ) |
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| 5 | simprll | |- ( ( i e. ( G GraphIso H ) /\ ( ( G e. USPGraph /\ H e. USPGraph ) /\ ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) ) ) -> G e. USPGraph ) |
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| 6 | simprlr | |- ( ( i e. ( G GraphIso H ) /\ ( ( G e. USPGraph /\ H e. USPGraph ) /\ ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) ) ) -> H e. USPGraph ) |
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| 7 | simpl | |- ( ( i e. ( G GraphIso H ) /\ ( ( G e. USPGraph /\ H e. USPGraph ) /\ ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) ) ) -> i e. ( G GraphIso H ) ) |
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| 8 | 2fveq3 | |- ( x = j -> ( ( iEdg ` G ) ` ( f ` x ) ) = ( ( iEdg ` G ) ` ( f ` j ) ) ) |
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| 9 | 8 | imaeq2d | |- ( x = j -> ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) = ( i " ( ( iEdg ` G ) ` ( f ` j ) ) ) ) |
| 10 | 9 | fveq2d | |- ( x = j -> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) = ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` j ) ) ) ) ) |
| 11 | 10 | cbvmptv | |- ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) = ( j e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` j ) ) ) ) ) |
| 12 | cycliswlk | |- ( f ( Cycles ` G ) p -> f ( Walks ` G ) p ) |
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| 13 | 12 | ad2antrl | |- ( ( ( G e. USPGraph /\ H e. USPGraph ) /\ ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) ) -> f ( Walks ` G ) p ) |
| 14 | 13 | adantl | |- ( ( i e. ( G GraphIso H ) /\ ( ( G e. USPGraph /\ H e. USPGraph ) /\ ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) ) ) -> f ( Walks ` G ) p ) |
| 15 | 3 4 5 6 7 11 14 | upgrimwlklen | |- ( ( i e. ( G GraphIso H ) /\ ( ( G e. USPGraph /\ H e. USPGraph ) /\ ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) ) ) -> ( ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ( Walks ` H ) ( i o. p ) /\ ( # ` ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ) = ( # ` f ) ) ) |
| 16 | simprrl | |- ( ( i e. ( G GraphIso H ) /\ ( ( G e. USPGraph /\ H e. USPGraph ) /\ ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) ) ) -> f ( Cycles ` G ) p ) |
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| 17 | 3 4 5 6 7 11 16 | upgrimcycls | |- ( ( i e. ( G GraphIso H ) /\ ( ( G e. USPGraph /\ H e. USPGraph ) /\ ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) ) ) -> ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ( Cycles ` H ) ( i o. p ) ) |
| 18 | simp3 | |- ( ( ( i e. ( G GraphIso H ) /\ ( ( G e. USPGraph /\ H e. USPGraph ) /\ ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) ) ) /\ ( ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ( Walks ` H ) ( i o. p ) /\ ( # ` ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ) = ( # ` f ) ) /\ ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ( Cycles ` H ) ( i o. p ) ) -> ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ( Cycles ` H ) ( i o. p ) ) |
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| 19 | simp2r | |- ( ( ( i e. ( G GraphIso H ) /\ ( ( G e. USPGraph /\ H e. USPGraph ) /\ ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) ) ) /\ ( ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ( Walks ` H ) ( i o. p ) /\ ( # ` ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ) = ( # ` f ) ) /\ ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ( Cycles ` H ) ( i o. p ) ) -> ( # ` ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ) = ( # ` f ) ) |
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| 20 | simprrr | |- ( ( i e. ( G GraphIso H ) /\ ( ( G e. USPGraph /\ H e. USPGraph ) /\ ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) ) ) -> ( # ` f ) = N ) |
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| 21 | 20 | 3ad2ant1 | |- ( ( ( i e. ( G GraphIso H ) /\ ( ( G e. USPGraph /\ H e. USPGraph ) /\ ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) ) ) /\ ( ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ( Walks ` H ) ( i o. p ) /\ ( # ` ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ) = ( # ` f ) ) /\ ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ( Cycles ` H ) ( i o. p ) ) -> ( # ` f ) = N ) |
| 22 | 19 21 | eqtrd | |- ( ( ( i e. ( G GraphIso H ) /\ ( ( G e. USPGraph /\ H e. USPGraph ) /\ ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) ) ) /\ ( ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ( Walks ` H ) ( i o. p ) /\ ( # ` ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ) = ( # ` f ) ) /\ ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ( Cycles ` H ) ( i o. p ) ) -> ( # ` ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ) = N ) |
| 23 | vex | |- i e. _V |
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| 24 | vex | |- p e. _V |
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| 25 | 23 24 | coex | |- ( i o. p ) e. _V |
| 26 | vex | |- f e. _V |
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| 27 | 26 | dmex | |- dom f e. _V |
| 28 | 27 | mptex | |- ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) e. _V |
| 29 | breq12 | |- ( ( g = ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) /\ q = ( i o. p ) ) -> ( g ( Cycles ` H ) q <-> ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ( Cycles ` H ) ( i o. p ) ) ) |
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| 30 | 29 | ancoms | |- ( ( q = ( i o. p ) /\ g = ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ) -> ( g ( Cycles ` H ) q <-> ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ( Cycles ` H ) ( i o. p ) ) ) |
| 31 | fveqeq2 | |- ( g = ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) -> ( ( # ` g ) = N <-> ( # ` ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ) = N ) ) |
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| 32 | 31 | adantl | |- ( ( q = ( i o. p ) /\ g = ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ) -> ( ( # ` g ) = N <-> ( # ` ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ) = N ) ) |
| 33 | 30 32 | anbi12d | |- ( ( q = ( i o. p ) /\ g = ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ) -> ( ( g ( Cycles ` H ) q /\ ( # ` g ) = N ) <-> ( ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ( Cycles ` H ) ( i o. p ) /\ ( # ` ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ) = N ) ) ) |
| 34 | 25 28 33 | spc2ev | |- ( ( ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ( Cycles ` H ) ( i o. p ) /\ ( # ` ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ) = N ) -> E. q E. g ( g ( Cycles ` H ) q /\ ( # ` g ) = N ) ) |
| 35 | 18 22 34 | syl2anc | |- ( ( ( i e. ( G GraphIso H ) /\ ( ( G e. USPGraph /\ H e. USPGraph ) /\ ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) ) ) /\ ( ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ( Walks ` H ) ( i o. p ) /\ ( # ` ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ) = ( # ` f ) ) /\ ( x e. dom f |-> ( `' ( iEdg ` H ) ` ( i " ( ( iEdg ` G ) ` ( f ` x ) ) ) ) ) ( Cycles ` H ) ( i o. p ) ) -> E. q E. g ( g ( Cycles ` H ) q /\ ( # ` g ) = N ) ) |
| 36 | 15 17 35 | mpd3an23 | |- ( ( i e. ( G GraphIso H ) /\ ( ( G e. USPGraph /\ H e. USPGraph ) /\ ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) ) ) -> E. q E. g ( g ( Cycles ` H ) q /\ ( # ` g ) = N ) ) |
| 37 | 36 | ex | |- ( i e. ( G GraphIso H ) -> ( ( ( G e. USPGraph /\ H e. USPGraph ) /\ ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) ) -> E. q E. g ( g ( Cycles ` H ) q /\ ( # ` g ) = N ) ) ) |
| 38 | 37 | rexlimivw | |- ( E. i e. ( G GraphIso H ) i e. ( G GraphIso H ) -> ( ( ( G e. USPGraph /\ H e. USPGraph ) /\ ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) ) -> E. q E. g ( g ( Cycles ` H ) q /\ ( # ` g ) = N ) ) ) |
| 39 | 2 38 | syl | |- ( ( G GraphIso H ) =/= (/) -> ( ( ( G e. USPGraph /\ H e. USPGraph ) /\ ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) ) -> E. q E. g ( g ( Cycles ` H ) q /\ ( # ` g ) = N ) ) ) |
| 40 | 1 39 | sylbi | |- ( G ~=gr H -> ( ( ( G e. USPGraph /\ H e. USPGraph ) /\ ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) ) -> E. q E. g ( g ( Cycles ` H ) q /\ ( # ` g ) = N ) ) ) |
| 41 | 40 | expdcom | |- ( ( G e. USPGraph /\ H e. USPGraph ) -> ( ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) -> ( G ~=gr H -> E. q E. g ( g ( Cycles ` H ) q /\ ( # ` g ) = N ) ) ) ) |
| 42 | 41 | exlimdvv | |- ( ( G e. USPGraph /\ H e. USPGraph ) -> ( E. p E. f ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) -> ( G ~=gr H -> E. q E. g ( g ( Cycles ` H ) q /\ ( # ` g ) = N ) ) ) ) |
| 43 | 42 | imp | |- ( ( ( G e. USPGraph /\ H e. USPGraph ) /\ E. p E. f ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) ) -> ( G ~=gr H -> E. q E. g ( g ( Cycles ` H ) q /\ ( # ` g ) = N ) ) ) |
| 44 | breq12 | |- ( ( f = g /\ p = q ) -> ( f ( Cycles ` H ) p <-> g ( Cycles ` H ) q ) ) |
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| 45 | 44 | ancoms | |- ( ( p = q /\ f = g ) -> ( f ( Cycles ` H ) p <-> g ( Cycles ` H ) q ) ) |
| 46 | fveqeq2 | |- ( f = g -> ( ( # ` f ) = N <-> ( # ` g ) = N ) ) |
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| 47 | 46 | adantl | |- ( ( p = q /\ f = g ) -> ( ( # ` f ) = N <-> ( # ` g ) = N ) ) |
| 48 | 45 47 | anbi12d | |- ( ( p = q /\ f = g ) -> ( ( f ( Cycles ` H ) p /\ ( # ` f ) = N ) <-> ( g ( Cycles ` H ) q /\ ( # ` g ) = N ) ) ) |
| 49 | 48 | cbvex2vw | |- ( E. p E. f ( f ( Cycles ` H ) p /\ ( # ` f ) = N ) <-> E. q E. g ( g ( Cycles ` H ) q /\ ( # ` g ) = N ) ) |
| 50 | 43 49 | imbitrrdi | |- ( ( ( G e. USPGraph /\ H e. USPGraph ) /\ E. p E. f ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) ) -> ( G ~=gr H -> E. p E. f ( f ( Cycles ` H ) p /\ ( # ` f ) = N ) ) ) |
| 51 | 50 | con3d | |- ( ( ( G e. USPGraph /\ H e. USPGraph ) /\ E. p E. f ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) ) -> ( -. E. p E. f ( f ( Cycles ` H ) p /\ ( # ` f ) = N ) -> -. G ~=gr H ) ) |
| 52 | 51 | expimpd | |- ( ( G e. USPGraph /\ H e. USPGraph ) -> ( ( E. p E. f ( f ( Cycles ` G ) p /\ ( # ` f ) = N ) /\ -. E. p E. f ( f ( Cycles ` H ) p /\ ( # ` f ) = N ) ) -> -. G ~=gr H ) ) |