Metamath Proof Explorer


Theorem upgrimspths

Description: Graph isomorphisms between simple pseudographs map simple paths onto simple paths. (Contributed by AV, 31-Oct-2025)

Ref Expression
Hypotheses upgrimwlk.i
|- I = ( iEdg ` G )
upgrimwlk.j
|- J = ( iEdg ` H )
upgrimwlk.g
|- ( ph -> G e. USPGraph )
upgrimwlk.h
|- ( ph -> H e. USPGraph )
upgrimwlk.n
|- ( ph -> N e. ( G GraphIso H ) )
upgrimwlk.e
|- E = ( x e. dom F |-> ( `' J ` ( N " ( I ` ( F ` x ) ) ) ) )
upgrimspths.s
|- ( ph -> F ( SPaths ` G ) P )
Assertion upgrimspths
|- ( ph -> E ( SPaths ` H ) ( N o. P ) )

Proof

Step Hyp Ref Expression
1 upgrimwlk.i
 |-  I = ( iEdg ` G )
2 upgrimwlk.j
 |-  J = ( iEdg ` H )
3 upgrimwlk.g
 |-  ( ph -> G e. USPGraph )
4 upgrimwlk.h
 |-  ( ph -> H e. USPGraph )
5 upgrimwlk.n
 |-  ( ph -> N e. ( G GraphIso H ) )
6 upgrimwlk.e
 |-  E = ( x e. dom F |-> ( `' J ` ( N " ( I ` ( F ` x ) ) ) ) )
7 upgrimspths.s
 |-  ( ph -> F ( SPaths ` G ) P )
8 spthispth
 |-  ( F ( SPaths ` G ) P -> F ( Paths ` G ) P )
9 pthistrl
 |-  ( F ( Paths ` G ) P -> F ( Trails ` G ) P )
10 7 8 9 3syl
 |-  ( ph -> F ( Trails ` G ) P )
11 1 2 3 4 5 6 10 upgrimtrls
 |-  ( ph -> E ( Trails ` H ) ( N o. P ) )
12 isspth
 |-  ( F ( SPaths ` G ) P <-> ( F ( Trails ` G ) P /\ Fun `' P ) )
13 12 simprbi
 |-  ( F ( SPaths ` G ) P -> Fun `' P )
14 7 13 syl
 |-  ( ph -> Fun `' P )
15 eqid
 |-  ( Vtx ` G ) = ( Vtx ` G )
16 eqid
 |-  ( Vtx ` H ) = ( Vtx ` H )
17 15 16 grimf1o
 |-  ( N e. ( G GraphIso H ) -> N : ( Vtx ` G ) -1-1-onto-> ( Vtx ` H ) )
18 dff1o3
 |-  ( N : ( Vtx ` G ) -1-1-onto-> ( Vtx ` H ) <-> ( N : ( Vtx ` G ) -onto-> ( Vtx ` H ) /\ Fun `' N ) )
19 18 simprbi
 |-  ( N : ( Vtx ` G ) -1-1-onto-> ( Vtx ` H ) -> Fun `' N )
20 5 17 19 3syl
 |-  ( ph -> Fun `' N )
21 funco
 |-  ( ( Fun `' P /\ Fun `' N ) -> Fun ( `' P o. `' N ) )
22 14 20 21 syl2anc
 |-  ( ph -> Fun ( `' P o. `' N ) )
23 cnvco
 |-  `' ( N o. P ) = ( `' P o. `' N )
24 23 funeqi
 |-  ( Fun `' ( N o. P ) <-> Fun ( `' P o. `' N ) )
25 22 24 sylibr
 |-  ( ph -> Fun `' ( N o. P ) )
26 isspth
 |-  ( E ( SPaths ` H ) ( N o. P ) <-> ( E ( Trails ` H ) ( N o. P ) /\ Fun `' ( N o. P ) ) )
27 11 25 26 sylanbrc
 |-  ( ph -> E ( SPaths ` H ) ( N o. P ) )