Metamath Proof Explorer


Theorem gpg5gricstgr3

Description: Each closed neighborhood in a generalized Petersen graph G(N,K) of order 10 ( N = 5 ), which is either the Petersen graph G(5,2) or the 5-prism G(5,1), is isomorphic to a 3-star. (Contributed by AV, 13-Sep-2025)

Ref Expression
Hypothesis gpg5gricstgr3.g No typesetting found for |- G = ( 5 gPetersenGr K ) with typecode |-
Assertion gpg5gricstgr3 Could not format assertion : No typesetting found for |- ( ( K e. ( 1 ... 2 ) /\ V e. ( Vtx ` G ) ) -> ( G ISubGr ( G ClNeighbVtx V ) ) ~=gr ( StarGr ` 3 ) ) with typecode |-

Proof

Step Hyp Ref Expression
1 gpg5gricstgr3.g Could not format G = ( 5 gPetersenGr K ) : No typesetting found for |- G = ( 5 gPetersenGr K ) with typecode |-
2 5eluz3 5 3
3 2z 2
4 fzval3 2 1 2 = 1 ..^ 2 + 1
5 3 4 ax-mp 1 2 = 1 ..^ 2 + 1
6 2p1e3 2 + 1 = 3
7 6 oveq2i 1 ..^ 2 + 1 = 1 ..^ 3
8 ceil5half3 5 2 = 3
9 8 eqcomi 3 = 5 2
10 9 oveq2i 1 ..^ 3 = 1 ..^ 5 2
11 5 7 10 3eqtri 1 2 = 1 ..^ 5 2
12 11 eleq2i K 1 2 K 1 ..^ 5 2
13 12 biimpi K 1 2 K 1 ..^ 5 2
14 gpgusgra Could not format ( ( 5 e. ( ZZ>= ` 3 ) /\ K e. ( 1 ..^ ( |^ ` ( 5 / 2 ) ) ) ) -> ( 5 gPetersenGr K ) e. USGraph ) : No typesetting found for |- ( ( 5 e. ( ZZ>= ` 3 ) /\ K e. ( 1 ..^ ( |^ ` ( 5 / 2 ) ) ) ) -> ( 5 gPetersenGr K ) e. USGraph ) with typecode |-
15 1 14 eqeltrid 5 3 K 1 ..^ 5 2 G USGraph
16 2 13 15 sylancr K 1 2 G USGraph
17 16 anim1i K 1 2 V Vtx G G USGraph V Vtx G
18 eqidd K 1 2 V Vtx G 5 = 5
19 13 adantr K 1 2 V Vtx G K 1 ..^ 5 2
20 simpr K 1 2 V Vtx G V Vtx G
21 eqid 1 ..^ 5 2 = 1 ..^ 5 2
22 eqid Vtx G = Vtx G
23 eqid G NeighbVtx V = G NeighbVtx V
24 eqid Edg G = Edg G
25 21 1 22 23 24 gpg5nbgr3star 5 = 5 K 1 ..^ 5 2 V Vtx G G NeighbVtx V = 3 x G NeighbVtx V y G NeighbVtx V x y Edg G
26 18 19 20 25 syl3anc K 1 2 V Vtx G G NeighbVtx V = 3 x G NeighbVtx V y G NeighbVtx V x y Edg G
27 eqid G ClNeighbVtx V = G ClNeighbVtx V
28 3nn0 3 0
29 eqid Could not format ( StarGr ` 3 ) = ( StarGr ` 3 ) : No typesetting found for |- ( StarGr ` 3 ) = ( StarGr ` 3 ) with typecode |-
30 eqid Could not format ( Vtx ` ( StarGr ` 3 ) ) = ( Vtx ` ( StarGr ` 3 ) ) : No typesetting found for |- ( Vtx ` ( StarGr ` 3 ) ) = ( Vtx ` ( StarGr ` 3 ) ) with typecode |-
31 22 23 27 28 29 30 24 isubgr3stgr Could not format ( ( G e. USGraph /\ V e. ( Vtx ` G ) ) -> ( ( ( # ` ( G NeighbVtx V ) ) = 3 /\ A. x e. ( G NeighbVtx V ) A. y e. ( G NeighbVtx V ) { x , y } e/ ( Edg ` G ) ) -> ( G ISubGr ( G ClNeighbVtx V ) ) ~=gr ( StarGr ` 3 ) ) ) : No typesetting found for |- ( ( G e. USGraph /\ V e. ( Vtx ` G ) ) -> ( ( ( # ` ( G NeighbVtx V ) ) = 3 /\ A. x e. ( G NeighbVtx V ) A. y e. ( G NeighbVtx V ) { x , y } e/ ( Edg ` G ) ) -> ( G ISubGr ( G ClNeighbVtx V ) ) ~=gr ( StarGr ` 3 ) ) ) with typecode |-
32 17 26 31 sylc Could not format ( ( K e. ( 1 ... 2 ) /\ V e. ( Vtx ` G ) ) -> ( G ISubGr ( G ClNeighbVtx V ) ) ~=gr ( StarGr ` 3 ) ) : No typesetting found for |- ( ( K e. ( 1 ... 2 ) /\ V e. ( Vtx ` G ) ) -> ( G ISubGr ( G ClNeighbVtx V ) ) ~=gr ( StarGr ` 3 ) ) with typecode |-