P. 483 of Theorem List - Metamath Proof Explorer

Theorem List for Metamath Proof Explorer - 48201-48300   *Has distinct variable group(s)

Type	Label	Description
Statement
Theorem	stgrusgra 48201	The star graph SN is a simple graph. (Contributed by AV, 11-Sep-2025.)
⊢ (𝑁 ∈ ℕ0 → (StarGr‘𝑁) ∈ USGraph)
Theorem	stgr0 48202	The star graph S0 consists of a single vertex without edges. (Contributed by AV, 11-Sep-2025.)
⊢ (StarGr‘0) = {⟨(Base‘ndx), {0}⟩, ⟨(.ef‘ndx), ∅⟩}
Theorem	stgr1 48203	The star graph S1 consists of a single simple edge. (Contributed by AV, 11-Sep-2025.)
⊢ (StarGr‘1) = {⟨(Base‘ndx), {0, 1}⟩, ⟨(.ef‘ndx), ( I ↾ {{0, 1}})⟩}
Theorem	stgrvtx0 48204	The center ("internal node") of a star graph SN. (Contributed by AV, 12-Sep-2025.)
⊢ 𝐺 = (StarGr‘𝑁)    &   ⊢ 𝑉 = (Vtx‘𝐺)    ⇒   ⊢ (𝑁 ∈ ℕ0 → 0 ∈ 𝑉)
Theorem	stgrorder 48205	The order of a star graph SN. (Contributed by AV, 12-Sep-2025.)
⊢ 𝐺 = (StarGr‘𝑁)    &   ⊢ 𝑉 = (Vtx‘𝐺)    ⇒   ⊢ (𝑁 ∈ ℕ0 → (♯‘𝑉) = (𝑁 + 1))
Theorem	stgrnbgr0 48206	All vertices of a star graph SN except the center are in the (open) neighborhood of the center. (Contributed by AV, 12-Sep-2025.)
⊢ 𝐺 = (StarGr‘𝑁)    &   ⊢ 𝑉 = (Vtx‘𝐺)    ⇒   ⊢ (𝑁 ∈ ℕ0 → (𝐺 NeighbVtx 0) = (𝑉 ∖ {0}))
Theorem	stgrclnbgr0 48207	All vertices of a star graph SN are in the closed neighborhood of the center. (Contributed by AV, 12-Sep-2025.)
⊢ 𝐺 = (StarGr‘𝑁)    &   ⊢ 𝑉 = (Vtx‘𝐺)    ⇒   ⊢ (𝑁 ∈ ℕ0 → (𝐺 ClNeighbVtx 0) = 𝑉)
Theorem	isubgr3stgrlem1 48208	Lemma 1 for isubgr3stgr 48217. (Contributed by AV, 16-Sep-2025.)
⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑈 = (𝐺 NeighbVtx 𝑋)    &   ⊢ 𝐶 = (𝐺 ClNeighbVtx 𝑋)    &   ⊢ 𝐹 = (𝐻 ∪ {⟨𝑋, 𝑌⟩})    ⇒   ⊢ ((𝐻:𝑈–1-1-onto→𝑅 ∧ 𝑋 ∈ 𝑉 ∧ (𝑌 ∈ 𝑊 ∧ 𝑌 ∉ 𝑅)) → 𝐹:𝐶–1-1-onto→(𝑅 ∪ {𝑌}))
Theorem	isubgr3stgrlem2 48209*	Lemma 2 for isubgr3stgr 48217. (Contributed by AV, 16-Sep-2025.)
⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑈 = (𝐺 NeighbVtx 𝑋)    &   ⊢ 𝐶 = (𝐺 ClNeighbVtx 𝑋)    &   ⊢ 𝑁 ∈ ℕ0    &   ⊢ 𝑆 = (StarGr‘𝑁)    &   ⊢ 𝑊 = (Vtx‘𝑆)    ⇒   ⊢ ((𝐺 ∈ USGraph ∧ 𝑋 ∈ 𝑉 ∧ (♯‘𝑈) = 𝑁) → ∃𝑓 𝑓:𝑈–1-1-onto→(𝑊 ∖ {0}))
Theorem	isubgr3stgrlem3 48210*	Lemma 3 for isubgr3stgr 48217. (Contributed by AV, 17-Sep-2025.)
⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑈 = (𝐺 NeighbVtx 𝑋)    &   ⊢ 𝐶 = (𝐺 ClNeighbVtx 𝑋)    &   ⊢ 𝑁 ∈ ℕ0    &   ⊢ 𝑆 = (StarGr‘𝑁)    &   ⊢ 𝑊 = (Vtx‘𝑆)    ⇒   ⊢ ((𝐺 ∈ USGraph ∧ 𝑋 ∈ 𝑉 ∧ (♯‘𝑈) = 𝑁) → ∃𝑔(𝑔:𝐶–1-1-onto→𝑊 ∧ (𝑔‘𝑋) = 0))
Theorem	isubgr3stgrlem4 48211*	Lemma 4 for isubgr3stgr 48217. (Contributed by AV, 24-Sep-2025.)
⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑈 = (𝐺 NeighbVtx 𝑋)    &   ⊢ 𝐶 = (𝐺 ClNeighbVtx 𝑋)    &   ⊢ 𝑁 ∈ ℕ0    &   ⊢ 𝑆 = (StarGr‘𝑁)    &   ⊢ 𝑊 = (Vtx‘𝑆)    &   ⊢ 𝐸 = (Edg‘𝐺)    ⇒   ⊢ ((𝐴 = 𝑋 ∧ (𝐹:𝐶–1-1-onto→𝑊 ∧ (𝐹‘𝑋) = 0) ∧ (𝐴 ≠ 𝐵 ∧ 𝐴 ∈ 𝐶 ∧ 𝐵 ∈ 𝐶)) → ∃𝑧 ∈ (1...𝑁)(𝐹 “ {𝐴, 𝐵}) = {0, 𝑧})
Theorem	isubgr3stgrlem5 48212*	Lemma 5 for isubgr3stgr 48217. (Contributed by AV, 24-Sep-2025.)
⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑈 = (𝐺 NeighbVtx 𝑋)    &   ⊢ 𝐶 = (𝐺 ClNeighbVtx 𝑋)    &   ⊢ 𝑁 ∈ ℕ0    &   ⊢ 𝑆 = (StarGr‘𝑁)    &   ⊢ 𝑊 = (Vtx‘𝑆)    &   ⊢ 𝐸 = (Edg‘𝐺)    &   ⊢ 𝐼 = (Edg‘(𝐺 ISubGr 𝐶))    &   ⊢ 𝐻 = (𝑖 ∈ 𝐼 ↦ (𝐹 “ 𝑖))    ⇒   ⊢ ((𝐹:𝐶⟶𝑊 ∧ 𝑌 ∈ 𝐼) → (𝐻‘𝑌) = (𝐹 “ 𝑌))
Theorem	isubgr3stgrlem6 48213*	Lemma 6 for isubgr3stgr 48217. (Contributed by AV, 24-Sep-2025.)
⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑈 = (𝐺 NeighbVtx 𝑋)    &   ⊢ 𝐶 = (𝐺 ClNeighbVtx 𝑋)    &   ⊢ 𝑁 ∈ ℕ0    &   ⊢ 𝑆 = (StarGr‘𝑁)    &   ⊢ 𝑊 = (Vtx‘𝑆)    &   ⊢ 𝐸 = (Edg‘𝐺)    &   ⊢ 𝐼 = (Edg‘(𝐺 ISubGr 𝐶))    &   ⊢ 𝐻 = (𝑖 ∈ 𝐼 ↦ (𝐹 “ 𝑖))    ⇒   ⊢ ((((𝐺 ∈ USGraph ∧ 𝑋 ∈ 𝑉) ∧ ((♯‘𝑈) = 𝑁 ∧ ∀𝑥 ∈ 𝑈 ∀𝑦 ∈ 𝑈 {𝑥, 𝑦} ∉ 𝐸)) ∧ (𝐹:𝐶–1-1-onto→𝑊 ∧ (𝐹‘𝑋) = 0)) → 𝐻:𝐼⟶(Edg‘(StarGr‘𝑁)))
Theorem	isubgr3stgrlem7 48214*	Lemma 7 for isubgr3stgr 48217. (Contributed by AV, 29-Sep-2025.)
⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑈 = (𝐺 NeighbVtx 𝑋)    &   ⊢ 𝐶 = (𝐺 ClNeighbVtx 𝑋)    &   ⊢ 𝑁 ∈ ℕ0    &   ⊢ 𝑆 = (StarGr‘𝑁)    &   ⊢ 𝑊 = (Vtx‘𝑆)    &   ⊢ 𝐸 = (Edg‘𝐺)    &   ⊢ 𝐼 = (Edg‘(𝐺 ISubGr 𝐶))    &   ⊢ 𝐻 = (𝑖 ∈ 𝐼 ↦ (𝐹 “ 𝑖))    ⇒   ⊢ (((𝐺 ∈ USGraph ∧ 𝑋 ∈ 𝑉) ∧ (𝐹:𝐶–1-1-onto→𝑊 ∧ (𝐹‘𝑋) = 0) ∧ 𝐽 ∈ (Edg‘(StarGr‘𝑁))) → (◡𝐹 “ 𝐽) ∈ 𝐼)
Theorem	isubgr3stgrlem8 48215*	Lemma 8 for isubgr3stgr 48217. (Contributed by AV, 29-Sep-2025.)
⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑈 = (𝐺 NeighbVtx 𝑋)    &   ⊢ 𝐶 = (𝐺 ClNeighbVtx 𝑋)    &   ⊢ 𝑁 ∈ ℕ0    &   ⊢ 𝑆 = (StarGr‘𝑁)    &   ⊢ 𝑊 = (Vtx‘𝑆)    &   ⊢ 𝐸 = (Edg‘𝐺)    &   ⊢ 𝐼 = (Edg‘(𝐺 ISubGr 𝐶))    &   ⊢ 𝐻 = (𝑖 ∈ 𝐼 ↦ (𝐹 “ 𝑖))    ⇒   ⊢ ((((𝐺 ∈ USGraph ∧ 𝑋 ∈ 𝑉) ∧ ((♯‘𝑈) = 𝑁 ∧ ∀𝑥 ∈ 𝑈 ∀𝑦 ∈ 𝑈 {𝑥, 𝑦} ∉ 𝐸)) ∧ (𝐹:𝐶–1-1-onto→𝑊 ∧ (𝐹‘𝑋) = 0)) → 𝐻:𝐼–1-1-onto→(Edg‘(StarGr‘𝑁)))
Theorem	isubgr3stgrlem9 48216*	Lemma 9 for isubgr3stgr 48217. (Contributed by AV, 29-Sep-2025.)
⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑈 = (𝐺 NeighbVtx 𝑋)    &   ⊢ 𝐶 = (𝐺 ClNeighbVtx 𝑋)    &   ⊢ 𝑁 ∈ ℕ0    &   ⊢ 𝑆 = (StarGr‘𝑁)    &   ⊢ 𝑊 = (Vtx‘𝑆)    &   ⊢ 𝐸 = (Edg‘𝐺)    &   ⊢ 𝐼 = (Edg‘(𝐺 ISubGr 𝐶))    &   ⊢ 𝐻 = (𝑖 ∈ 𝐼 ↦ (𝐹 “ 𝑖))    ⇒   ⊢ ((((𝐺 ∈ USGraph ∧ 𝑋 ∈ 𝑉) ∧ ((♯‘𝑈) = 𝑁 ∧ ∀𝑥 ∈ 𝑈 ∀𝑦 ∈ 𝑈 {𝑥, 𝑦} ∉ 𝐸)) ∧ (𝐹:𝐶–1-1-onto→𝑊 ∧ (𝐹‘𝑋) = 0)) → (𝐻:𝐼–1-1-onto→(Edg‘(StarGr‘𝑁)) ∧ ∀𝑒 ∈ 𝐼 (𝐹 “ 𝑒) = (𝐻‘𝑒)))
Theorem	isubgr3stgr 48217*	If a vertex of a simple graph has exactly 𝑁 (different) neighbors, and none of these neighbors are connected by an edge, then the (closed) neighborhood of this vertex induces a subgraph which is isomorphic to an 𝑁-star. (Contributed by AV, 29-Sep-2025.)
⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑈 = (𝐺 NeighbVtx 𝑋)    &   ⊢ 𝐶 = (𝐺 ClNeighbVtx 𝑋)    &   ⊢ 𝑁 ∈ ℕ0    &   ⊢ 𝑆 = (StarGr‘𝑁)    &   ⊢ 𝑊 = (Vtx‘𝑆)    &   ⊢ 𝐸 = (Edg‘𝐺)    ⇒   ⊢ ((𝐺 ∈ USGraph ∧ 𝑋 ∈ 𝑉) → (((♯‘𝑈) = 𝑁 ∧ ∀𝑥 ∈ 𝑈 ∀𝑦 ∈ 𝑈 {𝑥, 𝑦} ∉ 𝐸) → (𝐺 ISubGr 𝐶) ≃𝑔𝑟 (StarGr‘𝑁)))
21.48.15.7  Local isomorphisms of graphs This section is about local isomorphisms of graphs, which are a generalization of isomorphisms of graphs, i.e., every isomorphism between two graphs is also a local isomorphism between these graphs, see uhgrimgrlim 48229. This definition is according to a chat in mathoverflow (https://mathoverflow.net/questions/491133/locally-isomorphic-graphs 48229): roughly speaking, it restricts the correspondence of two graphs to their neighborhoods. Additionally, a binary relation ≃𝑙𝑔𝑟 is defined (see df-grlic 48223) which is true for two graphs iff there is a local isomorphism between these graphs. Then these graphs are called "locally isomorphic". Therefore, this relation is also called "is locally isomorphic to" relation. As a main result of this section, it is shown that the "is locally isomorphic to" relation is an equivalence relation (for hypergraphs), see grlicer 48258. The names and symbols are chosen analogously to group isomorphisms GrpIso (see df-gim 19188) and graph isomorphisms GraphIso (see df-grim 48120) resp. isomorphism between groups ≃𝑔 (see df-gic 19189) and isomorphism between graphs ≃𝑔𝑟 (see df-gric 48123). As discussed in the above mentioned chat in mathoverflow, it is shown that there are local isomorphisms between two graphs which are not (ordinary) isomorphisms between these graphs. In other words, there are two different locally isomorphic graphs which are not isomorphic, see lgricngricex 48371. Such two graphs are the two generalized Petersen graphs G(5,K) of order 10 (see definition df-gpg 48283), which are the Petersen graph G(5,2) and the 5-prism G(5,1), see gpg5ngric 48370.
Syntax	cgrlim 48218	The class of graph local isomorphism sets.
class GraphLocIso
Syntax	cgrlic 48219	The class of the graph local isomorphism relation.
class ≃𝑙𝑔𝑟
Definition	df-grlim 48220*	A local isomorphism of graphs is a bijection between the sets of vertices of two graphs that preserves local adjacency, i.e. the subgraph induced by the closed neighborhood of a vertex of the first graph and the subgraph induced by the closed neighborhood of the associated vertex of the second graph are isomorphic. See the following chat in mathoverflow: https://mathoverflow.net/questions/491133/locally-isomorphic-graphs. (Contributed by AV, 27-Apr-2025.)
⊢ GraphLocIso = (𝑔 ∈ V, ℎ ∈ V ↦ {𝑓 ∣ (𝑓:(Vtx‘𝑔)–1-1-onto→(Vtx‘ℎ) ∧ ∀𝑣 ∈ (Vtx‘𝑔)(𝑔 ISubGr (𝑔 ClNeighbVtx 𝑣)) ≃𝑔𝑟 (ℎ ISubGr (ℎ ClNeighbVtx (𝑓‘𝑣))))})
Theorem	grlimfn 48221	The graph local isomorphism function is a well-defined function. (Contributed by AV, 20-May-2025.)
⊢ GraphLocIso Fn (V × V)
Theorem	grlimdmrel 48222	The domain of the graph local isomorphism function is a relation. (Contributed by AV, 20-May-2025.)
⊢ Rel dom GraphLocIso
Definition	df-grlic 48223	Two graphs are said to be locally isomorphic iff they are connected by at least one local isomorphism. (Contributed by AV, 27-Apr-2025.)
⊢ ≃𝑙𝑔𝑟 = (◡ GraphLocIso “ (V ∖ 1o))
Theorem	isgrlim 48224*	A local isomorphism of graphs is a bijection between their vertices that preserves neighborhoods. (Contributed by AV, 20-May-2025.)
⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑊 = (Vtx‘𝐻)    ⇒   ⊢ ((𝐺 ∈ 𝑋 ∧ 𝐻 ∈ 𝑌 ∧ 𝐹 ∈ 𝑍) → (𝐹 ∈ (𝐺 GraphLocIso 𝐻) ↔ (𝐹:𝑉–1-1-onto→𝑊 ∧ ∀𝑣 ∈ 𝑉 (𝐺 ISubGr (𝐺 ClNeighbVtx 𝑣)) ≃𝑔𝑟 (𝐻 ISubGr (𝐻 ClNeighbVtx (𝐹‘𝑣))))))
Theorem	isgrlim2 48225*	A local isomorphism of graphs is a bijection between their vertices that preserves neighborhoods. Definitions expanded. (Contributed by AV, 29-May-2025.)
⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑊 = (Vtx‘𝐻)    &   ⊢ 𝑁 = (𝐺 ClNeighbVtx 𝑣)    &   ⊢ 𝑀 = (𝐻 ClNeighbVtx (𝐹‘𝑣))    &   ⊢ 𝐼 = (iEdg‘𝐺)    &   ⊢ 𝐽 = (iEdg‘𝐻)    &   ⊢ 𝐾 = {𝑥 ∈ dom 𝐼 ∣ (𝐼‘𝑥) ⊆ 𝑁}    &   ⊢ 𝐿 = {𝑥 ∈ dom 𝐽 ∣ (𝐽‘𝑥) ⊆ 𝑀}    ⇒   ⊢ ((𝐺 ∈ 𝑋 ∧ 𝐻 ∈ 𝑌 ∧ 𝐹 ∈ 𝑍) → (𝐹 ∈ (𝐺 GraphLocIso 𝐻) ↔ (𝐹:𝑉–1-1-onto→𝑊 ∧ ∀𝑣 ∈ 𝑉 ∃𝑓(𝑓:𝑁–1-1-onto→𝑀 ∧ ∃𝑔(𝑔:𝐾–1-1-onto→𝐿 ∧ ∀𝑖 ∈ 𝐾 (𝑓 “ (𝐼‘𝑖)) = (𝐽‘(𝑔‘𝑖)))))))
Theorem	grlimprop 48226*	Properties of a local isomorphism of graphs. (Contributed by AV, 21-May-2025.)
⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑊 = (Vtx‘𝐻)    ⇒   ⊢ (𝐹 ∈ (𝐺 GraphLocIso 𝐻) → (𝐹:𝑉–1-1-onto→𝑊 ∧ ∀𝑣 ∈ 𝑉 (𝐺 ISubGr (𝐺 ClNeighbVtx 𝑣)) ≃𝑔𝑟 (𝐻 ISubGr (𝐻 ClNeighbVtx (𝐹‘𝑣)))))
Theorem	grlimf1o 48227	A local isomorphism of graphs is a bijection between their vertices. (Contributed by AV, 21-May-2025.)
⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑊 = (Vtx‘𝐻)    ⇒   ⊢ (𝐹 ∈ (𝐺 GraphLocIso 𝐻) → 𝐹:𝑉–1-1-onto→𝑊)
Theorem	grlimprop2 48228*	Properties of a local isomorphism of graphs. (Contributed by AV, 29-May-2025.)
⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑊 = (Vtx‘𝐻)    &   ⊢ 𝑁 = (𝐺 ClNeighbVtx 𝑣)    &   ⊢ 𝑀 = (𝐻 ClNeighbVtx (𝐹‘𝑣))    &   ⊢ 𝐼 = (iEdg‘𝐺)    &   ⊢ 𝐽 = (iEdg‘𝐻)    &   ⊢ 𝐾 = {𝑥 ∈ dom 𝐼 ∣ (𝐼‘𝑥) ⊆ 𝑁}    &   ⊢ 𝐿 = {𝑥 ∈ dom 𝐽 ∣ (𝐽‘𝑥) ⊆ 𝑀}    ⇒   ⊢ (𝐹 ∈ (𝐺 GraphLocIso 𝐻) → (𝐹:𝑉–1-1-onto→𝑊 ∧ ∀𝑣 ∈ 𝑉 ∃𝑓(𝑓:𝑁–1-1-onto→𝑀 ∧ ∃𝑔(𝑔:𝐾–1-1-onto→𝐿 ∧ ∀𝑖 ∈ 𝐾 (𝑓 “ (𝐼‘𝑖)) = (𝐽‘(𝑔‘𝑖))))))
Theorem	uhgrimgrlim 48229	An isomorphism of hypergraphs is a local isomorphism between the two graphs. (Contributed by AV, 2-Jun-2025.)
⊢ ((𝐺 ∈ UHGraph ∧ 𝐻 ∈ UHGraph ∧ 𝐹 ∈ (𝐺 GraphIso 𝐻)) → 𝐹 ∈ (𝐺 GraphLocIso 𝐻))
Theorem	uspgrlimlem1 48230*	Lemma 1 for uspgrlim 48234. (Contributed by AV, 16-Aug-2025.)
⊢ 𝑀 = (𝐻 ClNeighbVtx 𝑋)    &   ⊢ 𝐽 = (Edg‘𝐻)    &   ⊢ 𝐿 = {𝑥 ∈ 𝐽 ∣ 𝑥 ⊆ 𝑀}    ⇒   ⊢ (𝐻 ∈ USPGraph → 𝐿 = ((iEdg‘𝐻) “ {𝑥 ∈ dom (iEdg‘𝐻) ∣ ((iEdg‘𝐻)‘𝑥) ⊆ 𝑀}))
Theorem	uspgrlimlem2 48231*	Lemma 2 for uspgrlim 48234. (Contributed by AV, 16-Aug-2025.)
⊢ 𝑀 = (𝐻 ClNeighbVtx 𝑋)    &   ⊢ 𝐽 = (Edg‘𝐻)    &   ⊢ 𝐿 = {𝑥 ∈ 𝐽 ∣ 𝑥 ⊆ 𝑀}    ⇒   ⊢ (𝐻 ∈ USPGraph → (◡(iEdg‘𝐻) “ 𝐿) = {𝑥 ∈ dom (iEdg‘𝐻) ∣ ((iEdg‘𝐻)‘𝑥) ⊆ 𝑀})
Theorem	uspgrlimlem3 48232*	Lemma 3 for uspgrlim 48234. (Contributed by AV, 16-Aug-2025.)
⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑊 = (Vtx‘𝐻)    &   ⊢ 𝑁 = (𝐺 ClNeighbVtx 𝑣)    &   ⊢ 𝑀 = (𝐻 ClNeighbVtx (𝐹‘𝑣))    &   ⊢ 𝐼 = (Edg‘𝐺)    &   ⊢ 𝐽 = (Edg‘𝐻)    &   ⊢ 𝐾 = {𝑥 ∈ 𝐼 ∣ 𝑥 ⊆ 𝑁}    &   ⊢ 𝐿 = {𝑥 ∈ 𝐽 ∣ 𝑥 ⊆ 𝑀}    ⇒   ⊢ ((𝐺 ∈ USPGraph ∧ ℎ:{𝑥 ∈ dom (iEdg‘𝐺) ∣ ((iEdg‘𝐺)‘𝑥) ⊆ 𝑁}–1-1-onto→𝑅 ∧ ∀𝑖 ∈ {𝑥 ∈ dom (iEdg‘𝐺) ∣ ((iEdg‘𝐺)‘𝑥) ⊆ 𝑁} (𝑓 “ ((iEdg‘𝐺)‘𝑖)) = ((iEdg‘𝐻)‘(ℎ‘𝑖))) → (𝑒 ∈ 𝐾 → (𝑓 “ 𝑒) = ((((iEdg‘𝐻) ∘ ℎ) ∘ ◡(iEdg‘𝐺))‘𝑒)))
Theorem	uspgrlimlem4 48233*	Lemma 4 for uspgrlim 48234. (Contributed by AV, 16-Aug-2025.)
⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑊 = (Vtx‘𝐻)    &   ⊢ 𝑁 = (𝐺 ClNeighbVtx 𝑣)    &   ⊢ 𝑀 = (𝐻 ClNeighbVtx (𝐹‘𝑣))    &   ⊢ 𝐼 = (Edg‘𝐺)    &   ⊢ 𝐽 = (Edg‘𝐻)    &   ⊢ 𝐾 = {𝑥 ∈ 𝐼 ∣ 𝑥 ⊆ 𝑁}    &   ⊢ 𝐿 = {𝑥 ∈ 𝐽 ∣ 𝑥 ⊆ 𝑀}    ⇒   ⊢ (((𝐺 ∈ USPGraph ∧ 𝐻 ∈ USPGraph) ∧ (𝑔:𝐾–1-1-onto→𝐿 ∧ ∀𝑒 ∈ 𝐾 (𝑓 “ 𝑒) = (𝑔‘𝑒))) → ((𝑖 ∈ dom (iEdg‘𝐺) ∧ ((iEdg‘𝐺)‘𝑖) ⊆ 𝑁) → (𝑓 “ ((iEdg‘𝐺)‘𝑖)) = ((iEdg‘𝐻)‘(((◡(iEdg‘𝐻) ∘ 𝑔) ∘ (iEdg‘𝐺))‘𝑖))))
Theorem	uspgrlim 48234*	A local isomorphism of simple pseudographs is a bijection between their vertices that preserves neighborhoods, expressed by properties of their edges (not edge functions as in isgrlim2 48225). (Contributed by AV, 15-Aug-2025.)
⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑊 = (Vtx‘𝐻)    &   ⊢ 𝑁 = (𝐺 ClNeighbVtx 𝑣)    &   ⊢ 𝑀 = (𝐻 ClNeighbVtx (𝐹‘𝑣))    &   ⊢ 𝐼 = (Edg‘𝐺)    &   ⊢ 𝐽 = (Edg‘𝐻)    &   ⊢ 𝐾 = {𝑥 ∈ 𝐼 ∣ 𝑥 ⊆ 𝑁}    &   ⊢ 𝐿 = {𝑥 ∈ 𝐽 ∣ 𝑥 ⊆ 𝑀}    ⇒   ⊢ ((𝐺 ∈ USPGraph ∧ 𝐻 ∈ USPGraph ∧ 𝐹 ∈ 𝑍) → (𝐹 ∈ (𝐺 GraphLocIso 𝐻) ↔ (𝐹:𝑉–1-1-onto→𝑊 ∧ ∀𝑣 ∈ 𝑉 ∃𝑓(𝑓:𝑁–1-1-onto→𝑀 ∧ ∃𝑔(𝑔:𝐾–1-1-onto→𝐿 ∧ ∀𝑒 ∈ 𝐾 (𝑓 “ 𝑒) = (𝑔‘𝑒))))))
Theorem	usgrlimprop 48235*	Properties of a local isomorphism of simple pseudographs. (Contributed by AV, 17-Aug-2025.)
⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑊 = (Vtx‘𝐻)    &   ⊢ 𝑁 = (𝐺 ClNeighbVtx 𝑣)    &   ⊢ 𝑀 = (𝐻 ClNeighbVtx (𝐹‘𝑣))    &   ⊢ 𝐼 = (Edg‘𝐺)    &   ⊢ 𝐽 = (Edg‘𝐻)    &   ⊢ 𝐾 = {𝑥 ∈ 𝐼 ∣ 𝑥 ⊆ 𝑁}    &   ⊢ 𝐿 = {𝑥 ∈ 𝐽 ∣ 𝑥 ⊆ 𝑀}    ⇒   ⊢ ((𝐺 ∈ USPGraph ∧ 𝐻 ∈ USPGraph ∧ 𝐹 ∈ (𝐺 GraphLocIso 𝐻)) → (𝐹:𝑉–1-1-onto→𝑊 ∧ ∀𝑣 ∈ 𝑉 ∃𝑓(𝑓:𝑁–1-1-onto→𝑀 ∧ ∃𝑔(𝑔:𝐾–1-1-onto→𝐿 ∧ ∀𝑒 ∈ 𝐾 (𝑓 “ 𝑒) = (𝑔‘𝑒)))))
Theorem	clnbgrvtxedg 48236*	An edge 𝐸 containing a vertex 𝐴 is an edge in the closed neighborhood of this vertex 𝐴. (Contributed by AV, 25-Dec-2025.)
⊢ 𝑁 = (𝐺 ClNeighbVtx 𝐴)    &   ⊢ 𝐼 = (Edg‘𝐺)    &   ⊢ 𝐾 = {𝑥 ∈ 𝐼 ∣ 𝑥 ⊆ 𝑁}    ⇒   ⊢ ((𝐺 ∈ UHGraph ∧ 𝐸 ∈ 𝐼 ∧ 𝐴 ∈ 𝐸) → 𝐸 ∈ 𝐾)
Theorem	grlimedgclnbgr 48237*	For two locally isomorphic graphs 𝐺 and 𝐻 and a vertex 𝐴 of 𝐺 there are two bijections 𝑓 and 𝑔 mapping the closed neighborhood 𝑁 of 𝐴 onto the closed neighborhood 𝑀 of (𝐹‘𝐴) and the edges between the vertices in 𝑁 onto the edges between the vertices in 𝑀, so that the mapped vertices of an edge 𝐸 containing the vertex 𝐴 is an edge between the vertices in 𝑀. (Contributed by AV, 25-Dec-2025.)
⊢ 𝑁 = (𝐺 ClNeighbVtx 𝐴)    &   ⊢ 𝐼 = (Edg‘𝐺)    &   ⊢ 𝐾 = {𝑥 ∈ 𝐼 ∣ 𝑥 ⊆ 𝑁}    &   ⊢ 𝑀 = (𝐻 ClNeighbVtx (𝐹‘𝐴))    &   ⊢ 𝐽 = (Edg‘𝐻)    &   ⊢ 𝐿 = {𝑥 ∈ 𝐽 ∣ 𝑥 ⊆ 𝑀}    ⇒   ⊢ (((𝐺 ∈ USPGraph ∧ 𝐻 ∈ USPGraph) ∧ 𝐹 ∈ (𝐺 GraphLocIso 𝐻) ∧ (𝐸 ∈ 𝐼 ∧ 𝐴 ∈ 𝐸)) → ∃𝑓∃𝑔(𝑓:𝑁–1-1-onto→𝑀 ∧ 𝑔:𝐾–1-1-onto→𝐿 ∧ (𝑓 “ 𝐸) = (𝑔‘𝐸)))
Theorem	grlimprclnbgr 48238*	For two locally isomorphic graphs 𝐺 and 𝐻 and a vertex 𝐴 of 𝐺 there are two bijections 𝑓 and 𝑔 mapping the closed neighborhood 𝑁 of 𝐴 onto the closed neighborhood 𝑀 of (𝐹‘𝐴) and the edges between the vertices in 𝑁 onto the edges between the vertices in 𝑀, so that the mapped vertices of an edge {𝐴, 𝐵} containing the vertex 𝐴 is an edge between the vertices in 𝑀. (Contributed by AV, 25-Dec-2025.)
⊢ 𝑁 = (𝐺 ClNeighbVtx 𝐴)    &   ⊢ 𝐼 = (Edg‘𝐺)    &   ⊢ 𝐾 = {𝑥 ∈ 𝐼 ∣ 𝑥 ⊆ 𝑁}    &   ⊢ 𝑀 = (𝐻 ClNeighbVtx (𝐹‘𝐴))    &   ⊢ 𝐽 = (Edg‘𝐻)    &   ⊢ 𝐿 = {𝑥 ∈ 𝐽 ∣ 𝑥 ⊆ 𝑀}    ⇒   ⊢ (((𝐺 ∈ USPGraph ∧ 𝐻 ∈ USPGraph) ∧ 𝐹 ∈ (𝐺 GraphLocIso 𝐻) ∧ (𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑊 ∧ {𝐴, 𝐵} ∈ 𝐼)) → ∃𝑓∃𝑔(𝑓:𝑁–1-1-onto→𝑀 ∧ 𝑔:𝐾–1-1-onto→𝐿 ∧ {(𝑓‘𝐴), (𝑓‘𝐵)} = (𝑔‘{𝐴, 𝐵})))
Theorem	grlimprclnbgredg 48239*	For two locally isomorphic graphs 𝐺 and 𝐻 and a vertex 𝐴 of 𝐺 there is a bijection 𝑓 mapping the closed neighborhood 𝑁 of 𝐴 onto the closed neighborhood 𝑀 of (𝐹‘𝐴), so that the mapped vertices of an edge {𝐴, 𝐵} containing the vertex 𝐴 is an edge between the vertices in 𝑀. (Contributed by AV, 27-Dec-2025.)
⊢ 𝑁 = (𝐺 ClNeighbVtx 𝐴)    &   ⊢ 𝐼 = (Edg‘𝐺)    &   ⊢ 𝐾 = {𝑥 ∈ 𝐼 ∣ 𝑥 ⊆ 𝑁}    &   ⊢ 𝑀 = (𝐻 ClNeighbVtx (𝐹‘𝐴))    &   ⊢ 𝐽 = (Edg‘𝐻)    &   ⊢ 𝐿 = {𝑥 ∈ 𝐽 ∣ 𝑥 ⊆ 𝑀}    ⇒   ⊢ (((𝐺 ∈ USPGraph ∧ 𝐻 ∈ USPGraph) ∧ 𝐹 ∈ (𝐺 GraphLocIso 𝐻) ∧ (𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑊 ∧ {𝐴, 𝐵} ∈ 𝐼)) → ∃𝑓(𝑓:𝑁–1-1-onto→𝑀 ∧ {(𝑓‘𝐴), (𝑓‘𝐵)} ∈ 𝐿))
Theorem	grlimpredg 48240*	For two locally isomorphic graphs 𝐺 and 𝐻 and a vertex 𝐴 of 𝐺 there is a bijection 𝑓 mapping the closed neighborhood 𝑁 of 𝐴 onto the closed neighborhood 𝑀 of (𝐹‘𝐴), so that the mapped vertices of an edge {𝐴, 𝐵} containing the vertex 𝐴 is an edge in 𝐻. (Contributed by AV, 27-Dec-2025.)
⊢ 𝑁 = (𝐺 ClNeighbVtx 𝐴)    &   ⊢ 𝐼 = (Edg‘𝐺)    &   ⊢ 𝐾 = {𝑥 ∈ 𝐼 ∣ 𝑥 ⊆ 𝑁}    &   ⊢ 𝑀 = (𝐻 ClNeighbVtx (𝐹‘𝐴))    &   ⊢ 𝐽 = (Edg‘𝐻)    &   ⊢ 𝐿 = {𝑥 ∈ 𝐽 ∣ 𝑥 ⊆ 𝑀}    ⇒   ⊢ (((𝐺 ∈ USPGraph ∧ 𝐻 ∈ USPGraph) ∧ 𝐹 ∈ (𝐺 GraphLocIso 𝐻) ∧ (𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑊 ∧ {𝐴, 𝐵} ∈ 𝐼)) → ∃𝑓(𝑓:𝑁–1-1-onto→𝑀 ∧ {(𝑓‘𝐴), (𝑓‘𝐵)} ∈ 𝐽))
Theorem	grlimprclnbgrvtx 48241*	For two locally isomorphic graphs 𝐺 and 𝐻 and a vertex 𝐴 of 𝐺 there is a bijection 𝑓 mapping the closed neighborhood 𝑁 of 𝐴 onto the closed neighborhood 𝑀 of (𝐹‘𝐴), so that the mapped vertices of an edge {𝐴, 𝐵} containing the vertex 𝐴 is an edge between the vertices in 𝑀 containing the vertex (𝐹‘𝐴). (Contributed by AV, 28-Dec-2025.)
⊢ 𝑁 = (𝐺 ClNeighbVtx 𝐴)    &   ⊢ 𝐼 = (Edg‘𝐺)    &   ⊢ 𝐾 = {𝑥 ∈ 𝐼 ∣ 𝑥 ⊆ 𝑁}    &   ⊢ 𝑀 = (𝐻 ClNeighbVtx (𝐹‘𝐴))    &   ⊢ 𝐽 = (Edg‘𝐻)    &   ⊢ 𝐿 = {𝑥 ∈ 𝐽 ∣ 𝑥 ⊆ 𝑀}    ⇒   ⊢ (((𝐺 ∈ USPGraph ∧ 𝐻 ∈ USPGraph) ∧ 𝐹 ∈ (𝐺 GraphLocIso 𝐻) ∧ (𝐴 ∈ 𝑉 ∧ 𝐵 ∈ 𝑊 ∧ {𝐴, 𝐵} ∈ 𝐼)) → ∃𝑓(𝑓:𝑁–1-1-onto→𝑀 ∧ ({(𝐹‘𝐴), (𝑓‘𝐵)} ∈ 𝐿 ∨ {(𝐹‘𝐴), (𝑓‘𝐴)} ∈ 𝐿)))
Theorem	grlimgredgex 48242*	Local isomorphisms between simple pseudographs map an edge onto an edge with an endpoint being the image of one of the endpoints of the first edge under the local isomorphism. (Contributed by AV, 28-Dec-2025.)
⊢ 𝐼 = (Edg‘𝐺)    &   ⊢ 𝐸 = (Edg‘𝐻)    &   ⊢ 𝑉 = (Vtx‘𝐻)    &   ⊢ (𝜑 → 𝐴 ∈ 𝑋)    &   ⊢ (𝜑 → 𝐵 ∈ 𝑌)    &   ⊢ (𝜑 → {𝐴, 𝐵} ∈ 𝐼)    &   ⊢ (𝜑 → 𝐺 ∈ USPGraph)    &   ⊢ (𝜑 → 𝐻 ∈ USPGraph)    &   ⊢ (𝜑 → 𝐹 ∈ (𝐺 GraphLocIso 𝐻))    ⇒   ⊢ (𝜑 → ∃𝑣 ∈ 𝑉 {(𝐹‘𝐴), 𝑣} ∈ 𝐸)
Theorem	grlimgrtrilem1 48243*	Lemma 3 for grlimgrtri 48245. (Contributed by AV, 24-Aug-2025.) (Proof shortened by AV, 27-Dec-2025.)
⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑁 = (𝐺 ClNeighbVtx 𝑎)    &   ⊢ 𝐼 = (Edg‘𝐺)    &   ⊢ 𝐾 = {𝑥 ∈ 𝐼 ∣ 𝑥 ⊆ 𝑁}    ⇒   ⊢ ((𝐺 ∈ UHGraph ∧ ({𝑎, 𝑏} ∈ 𝐼 ∧ {𝑎, 𝑐} ∈ 𝐼 ∧ {𝑏, 𝑐} ∈ 𝐼)) → ({𝑎, 𝑏} ∈ 𝐾 ∧ {𝑎, 𝑐} ∈ 𝐾 ∧ {𝑏, 𝑐} ∈ 𝐾))
Theorem	grlimgrtrilem2 48244*	Lemma 3 for grlimgrtri 48245. (Contributed by AV, 23-Aug-2025.)
⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑁 = (𝐺 ClNeighbVtx 𝑎)    &   ⊢ 𝐼 = (Edg‘𝐺)    &   ⊢ 𝐾 = {𝑥 ∈ 𝐼 ∣ 𝑥 ⊆ 𝑁}    &   ⊢ 𝑀 = (𝐻 ClNeighbVtx (𝐹‘𝑎))    &   ⊢ 𝐽 = (Edg‘𝐻)    &   ⊢ 𝐿 = {𝑥 ∈ 𝐽 ∣ 𝑥 ⊆ 𝑀}    ⇒   ⊢ (((𝑓:𝑁–1-1-onto→𝑀 ∧ 𝑔:𝐾–1-1-onto→𝐿) ∧ ∀𝑖 ∈ 𝐾 (𝑓 “ 𝑖) = (𝑔‘𝑖) ∧ {𝑏, 𝑐} ∈ 𝐾) → {(𝑓‘𝑏), (𝑓‘𝑐)} ∈ 𝐽)
Theorem	grlimgrtri 48245*	If one of two locally isomorphic graphs has a triangle, so does the other. The triangle in the other graph is not necessarily the image (𝐹 “ 𝑇) of the triangle 𝑇 in the first graph. (Contributed by AV, 24-Aug-2025.)
⊢ (𝜑 → 𝐺 ∈ USPGraph)    &   ⊢ (𝜑 → 𝐻 ∈ USPGraph)    &   ⊢ (𝜑 → 𝐹 ∈ (𝐺 GraphLocIso 𝐻))    &   ⊢ (𝜑 → 𝑇 ∈ (GrTriangles‘𝐺))    ⇒   ⊢ (𝜑 → ∃𝑡 𝑡 ∈ (GrTriangles‘𝐻))
Theorem	brgrlic 48246	The relation "is locally isomorphic to" for graphs. (Contributed by AV, 9-Jun-2025.)
⊢ (𝑅 ≃𝑙𝑔𝑟 𝑆 ↔ (𝑅 GraphLocIso 𝑆) ≠ ∅)
Theorem	brgrilci 48247	Prove that two graphs are locally isomorphic by an explicit local isomorphism. (Contributed by AV, 9-Jun-2025.)
⊢ (𝐹 ∈ (𝑅 GraphLocIso 𝑆) → 𝑅 ≃𝑙𝑔𝑟 𝑆)
Theorem	grlicrel 48248	The "is locally isomorphic to" relation for graphs is a relation. (Contributed by AV, 9-Jun-2025.)
⊢ Rel ≃𝑙𝑔𝑟
Theorem	grlicrcl 48249	Reverse closure of the "is locally isomorphic to" relation for graphs. (Contributed by AV, 9-Jun-2025.)
⊢ (𝐺 ≃𝑙𝑔𝑟 𝑆 → (𝐺 ∈ V ∧ 𝑆 ∈ V))
Theorem	dfgrlic2 48250*	Alternate, explicit definition of the "is locally isomorphic to" relation for two graphs. (Contributed by AV, 9-Jun-2025.)
⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑊 = (Vtx‘𝐻)    ⇒   ⊢ ((𝐺 ∈ 𝑋 ∧ 𝐻 ∈ 𝑌) → (𝐺 ≃𝑙𝑔𝑟 𝐻 ↔ ∃𝑓(𝑓:𝑉–1-1-onto→𝑊 ∧ ∀𝑣 ∈ 𝑉 (𝐺 ISubGr (𝐺 ClNeighbVtx 𝑣)) ≃𝑔𝑟 (𝐻 ISubGr (𝐻 ClNeighbVtx (𝑓‘𝑣))))))
Theorem	grilcbri 48251*	Implications of two graphs being locally isomorphic. (Contributed by AV, 9-Jun-2025.)
⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑊 = (Vtx‘𝐻)    ⇒   ⊢ (𝐺 ≃𝑙𝑔𝑟 𝐻 → ∃𝑓(𝑓:𝑉–1-1-onto→𝑊 ∧ ∀𝑣 ∈ 𝑉 (𝐺 ISubGr (𝐺 ClNeighbVtx 𝑣)) ≃𝑔𝑟 (𝐻 ISubGr (𝐻 ClNeighbVtx (𝑓‘𝑣)))))
Theorem	dfgrlic3 48252*	Alternate, explicit definition of the "is locally isomorphic to" relation for two graphs. (Contributed by AV, 9-Jun-2025.)
⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑊 = (Vtx‘𝐻)    &   ⊢ 𝐼 = (iEdg‘𝐺)    &   ⊢ 𝐽 = (iEdg‘𝐻)    &   ⊢ 𝑁 = (𝐺 ClNeighbVtx 𝑣)    &   ⊢ 𝑀 = (𝐻 ClNeighbVtx (𝑓‘𝑣))    &   ⊢ 𝐾 = {𝑥 ∈ dom 𝐼 ∣ (𝐼‘𝑥) ⊆ 𝑁}    &   ⊢ 𝐿 = {𝑥 ∈ dom 𝐽 ∣ (𝐽‘𝑥) ⊆ 𝑀}    ⇒   ⊢ ((𝐺 ∈ 𝑋 ∧ 𝐻 ∈ 𝑌) → (𝐺 ≃𝑙𝑔𝑟 𝐻 ↔ ∃𝑓(𝑓:𝑉–1-1-onto→𝑊 ∧ ∀𝑣 ∈ 𝑉 ∃𝑗(𝑗:𝑁–1-1-onto→𝑀 ∧ ∃𝑔(𝑔:𝐾–1-1-onto→𝐿 ∧ ∀𝑖 ∈ 𝐾 (𝑗 “ (𝐼‘𝑖)) = (𝐽‘(𝑔‘𝑖)))))))
Theorem	grilcbri2 48253*	Implications of two graphs being locally isomorphic. (Contributed by AV, 9-Jun-2025.)
⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑊 = (Vtx‘𝐻)    &   ⊢ 𝐼 = (iEdg‘𝐺)    &   ⊢ 𝐽 = (iEdg‘𝐻)    &   ⊢ 𝑁 = (𝐺 ClNeighbVtx 𝑋)    &   ⊢ 𝑀 = (𝐻 ClNeighbVtx (𝑓‘𝑋))    &   ⊢ 𝐾 = {𝑥 ∈ dom 𝐼 ∣ (𝐼‘𝑥) ⊆ 𝑁}    &   ⊢ 𝐿 = {𝑥 ∈ dom 𝐽 ∣ (𝐽‘𝑥) ⊆ 𝑀}    ⇒   ⊢ (𝐺 ≃𝑙𝑔𝑟 𝐻 → ∃𝑓(𝑓:𝑉–1-1-onto→𝑊 ∧ (𝑋 ∈ 𝑉 → ∃𝑗(𝑗:𝑁–1-1-onto→𝑀 ∧ ∃𝑔(𝑔:𝐾–1-1-onto→𝐿 ∧ ∀𝑖 ∈ 𝐾 (𝑗 “ (𝐼‘𝑖)) = (𝐽‘(𝑔‘𝑖)))))))
Theorem	grlicref 48254	Graph local isomorphism is reflexive for hypergraphs. (Contributed by AV, 9-Jun-2025.)
⊢ (𝐺 ∈ UHGraph → 𝐺 ≃𝑙𝑔𝑟 𝐺)
Theorem	grlicsym 48255	Graph local isomorphism is symmetric for hypergraphs. (Contributed by AV, 9-Jun-2025.)
⊢ (𝐺 ∈ UHGraph → (𝐺 ≃𝑙𝑔𝑟 𝑆 → 𝑆 ≃𝑙𝑔𝑟 𝐺))
Theorem	grlicsymb 48256	Graph local isomorphism is symmetric in both directions for hypergraphs. (Contributed by AV, 9-Jun-2025.)
⊢ ((𝐴 ∈ UHGraph ∧ 𝐵 ∈ UHGraph) → (𝐴 ≃𝑙𝑔𝑟 𝐵 ↔ 𝐵 ≃𝑙𝑔𝑟 𝐴))
Theorem	grlictr 48257	Graph local isomorphism is transitive. (Contributed by AV, 10-Jun-2025.)
⊢ ((𝑅 ≃𝑙𝑔𝑟 𝑆 ∧ 𝑆 ≃𝑙𝑔𝑟 𝑇) → 𝑅 ≃𝑙𝑔𝑟 𝑇)
Theorem	grlicer 48258	Local isomorphism is an equivalence relation on hypergraphs. (Contributed by AV, 11-Jun-2025.)
⊢ ( ≃𝑙𝑔𝑟 ∩ (UHGraph × UHGraph)) Er UHGraph
Theorem	grlicen 48259	Locally isomorphic graphs have equinumerous sets of vertices. (Contributed by AV, 11-Jun-2025.)
⊢ 𝐵 = (Vtx‘𝑅)    &   ⊢ 𝐶 = (Vtx‘𝑆)    ⇒   ⊢ (𝑅 ≃𝑙𝑔𝑟 𝑆 → 𝐵 ≈ 𝐶)
Theorem	gricgrlic 48260	Isomorphic hypergraphs are locally isomorphic. (Contributed by AV, 12-Jun-2025.) (Proof shortened by AV, 11-Jul-2025.)
⊢ ((𝐺 ∈ UHGraph ∧ 𝐻 ∈ UHGraph) → (𝐺 ≃𝑔𝑟 𝐻 → 𝐺 ≃𝑙𝑔𝑟 𝐻))
Theorem	clnbgr3stgrgrlim 48261*	If all (closed) neighborhoods of the vertices in two simple graphs with the same order induce a subgraph which is isomorphic to an 𝑁-star, then any bijection between the vertices is a local isomorphism between the two graphs. (Contributed by AV, 28-Dec-2025.)
⊢ 𝑁 ∈ ℕ0    &   ⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑊 = (Vtx‘𝐻)    ⇒   ⊢ (((𝐺 ∈ USGraph ∧ 𝐻 ∈ USGraph ∧ 𝐹:𝑉–1-1-onto→𝑊) ∧ ∀𝑥 ∈ 𝑉 (𝐺 ISubGr (𝐺 ClNeighbVtx 𝑥)) ≃𝑔𝑟 (StarGr‘𝑁) ∧ ∀𝑦 ∈ 𝑊 (𝐻 ISubGr (𝐻 ClNeighbVtx 𝑦)) ≃𝑔𝑟 (StarGr‘𝑁)) → 𝐹 ∈ (𝐺 GraphLocIso 𝐻))
Theorem	clnbgr3stgrgrlic 48262*	If all (closed) neighborhoods of the vertices in two simple graphs with the same order induce a subgraph which is isomorphic to an 𝑁-star, then the two graphs are locally isomorphic. (Contributed by AV, 29-Sep-2025.)
⊢ 𝑁 ∈ ℕ0    &   ⊢ 𝑉 = (Vtx‘𝐺)    &   ⊢ 𝑊 = (Vtx‘𝐻)    ⇒   ⊢ (((𝐺 ∈ USGraph ∧ 𝐻 ∈ USGraph ∧ 𝑉 ≈ 𝑊) ∧ ∀𝑥 ∈ 𝑉 (𝐺 ISubGr (𝐺 ClNeighbVtx 𝑥)) ≃𝑔𝑟 (StarGr‘𝑁) ∧ ∀𝑦 ∈ 𝑊 (𝐻 ISubGr (𝐻 ClNeighbVtx 𝑦)) ≃𝑔𝑟 (StarGr‘𝑁)) → 𝐺 ≃𝑙𝑔𝑟 𝐻)
Theorem	usgrexmpl1lem 48263*	Lemma for usgrexmpl1 48264. (Contributed by AV, 2-Aug-2025.)
⊢ 𝑉 = (0...5)    &   ⊢ 𝐸 = ⟨“{0, 1} {0, 2} {1, 2} {0, 3} {3, 4} {3, 5} {4, 5}”⟩    ⇒   ⊢ 𝐸:dom 𝐸–1-1→{𝑒 ∈ 𝒫 𝑉 ∣ (♯‘𝑒) = 2}
Theorem	usgrexmpl1 48264	𝐺 is a simple graph of six vertices 0, 1, 2, 3, 4, 5, with edges {0, 1}, {1, 2}, {0, 2}, {0, 3}, {3, 4}, {3, 5}, {4, 5}. (Contributed by AV, 3-Aug-2025.)
⊢ 𝑉 = (0...5)    &   ⊢ 𝐸 = ⟨“{0, 1} {0, 2} {1, 2} {0, 3} {3, 4} {3, 5} {4, 5}”⟩    &   ⊢ 𝐺 = ⟨𝑉, 𝐸⟩    ⇒   ⊢ 𝐺 ∈ USGraph
Theorem	usgrexmpl1vtx 48265	The vertices 0, 1, 2, 3, 4, 5 of the graph 𝐺 = ⟨𝑉, 𝐸⟩. (Contributed by AV, 3-Aug-2025.)
⊢ 𝑉 = (0...5)    &   ⊢ 𝐸 = ⟨“{0, 1} {0, 2} {1, 2} {0, 3} {3, 4} {3, 5} {4, 5}”⟩    &   ⊢ 𝐺 = ⟨𝑉, 𝐸⟩    ⇒   ⊢ (Vtx‘𝐺) = ({0, 1, 2} ∪ {3, 4, 5})
Theorem	usgrexmpl1edg 48266	The edges {0, 1}, {1, 2}, {0, 2}, {0, 3}, {3, 4}, {3, 5}, {4, 5} of the graph 𝐺 = ⟨𝑉, 𝐸⟩. (Contributed by AV, 3-Aug-2025.)
⊢ 𝑉 = (0...5)    &   ⊢ 𝐸 = ⟨“{0, 1} {0, 2} {1, 2} {0, 3} {3, 4} {3, 5} {4, 5}”⟩    &   ⊢ 𝐺 = ⟨𝑉, 𝐸⟩    ⇒   ⊢ (Edg‘𝐺) = ({{0, 3}} ∪ ({{0, 1}, {0, 2}, {1, 2}} ∪ {{3, 4}, {3, 5}, {4, 5}}))
Theorem	usgrexmpl1tri 48267	𝐺 contains a triangle 0, 1, 2, with corresponding edges {0, 1}, {1, 2}, {0, 2}. (Contributed by AV, 3-Aug-2025.)
⊢ 𝑉 = (0...5)    &   ⊢ 𝐸 = ⟨“{0, 1} {0, 2} {1, 2} {0, 3} {3, 4} {3, 5} {4, 5}”⟩    &   ⊢ 𝐺 = ⟨𝑉, 𝐸⟩    ⇒   ⊢ {0, 1, 2} ∈ (GrTriangles‘𝐺)
Theorem	usgrexmpl2lem 48268*	Lemma for usgrexmpl2 48269. (Contributed by AV, 3-Aug-2025.)
⊢ 𝑉 = (0...5)    &   ⊢ 𝐸 = ⟨“{0, 1} {1, 2} {2, 3} {3, 4} {4, 5} {0, 3} {0, 5}”⟩    ⇒   ⊢ 𝐸:dom 𝐸–1-1→{𝑒 ∈ 𝒫 𝑉 ∣ (♯‘𝑒) = 2}
Theorem	usgrexmpl2 48269	𝐺 is a simple graph of six vertices 0, 1, 2, 3, 4, 5, with edges {0, 1}, {1, 2}, {2, 3}, {0, 3}, {3, 4}, {4, 5}, {0, 5}. (Contributed by AV, 3-Aug-2025.)
⊢ 𝑉 = (0...5)    &   ⊢ 𝐸 = ⟨“{0, 1} {1, 2} {2, 3} {3, 4} {4, 5} {0, 3} {0, 5}”⟩    &   ⊢ 𝐺 = ⟨𝑉, 𝐸⟩    ⇒   ⊢ 𝐺 ∈ USGraph
Theorem	usgrexmpl2vtx 48270	The vertices 0, 1, 2, 3, 4, 5 of the graph 𝐺 = ⟨𝑉, 𝐸⟩. (Contributed by AV, 3-Aug-2025.)
⊢ 𝑉 = (0...5)    &   ⊢ 𝐸 = ⟨“{0, 1} {1, 2} {2, 3} {3, 4} {4, 5} {0, 3} {0, 5}”⟩    &   ⊢ 𝐺 = ⟨𝑉, 𝐸⟩    ⇒   ⊢ (Vtx‘𝐺) = ({0, 1, 2} ∪ {3, 4, 5})
Theorem	usgrexmpl2edg 48271	The edges {0, 1}, {1, 2}, {2, 3}, {0, 3}, {3, 4}, {4, 5}, {0, 5} of the graph 𝐺 = ⟨𝑉, 𝐸⟩. (Contributed by AV, 3-Aug-2025.)
⊢ 𝑉 = (0...5)    &   ⊢ 𝐸 = ⟨“{0, 1} {1, 2} {2, 3} {3, 4} {4, 5} {0, 3} {0, 5}”⟩    &   ⊢ 𝐺 = ⟨𝑉, 𝐸⟩    ⇒   ⊢ (Edg‘𝐺) = ({{0, 3}} ∪ ({{0, 1}, {1, 2}, {2, 3}} ∪ {{3, 4}, {4, 5}, {0, 5}}))
Theorem	usgrexmpl2nblem 48272*	Lemma for usgrexmpl2nb0 48273 etc. (Contributed by AV, 9-Aug-2025.)
⊢ 𝑉 = (0...5)    &   ⊢ 𝐸 = ⟨“{0, 1} {1, 2} {2, 3} {3, 4} {4, 5} {0, 3} {0, 5}”⟩    &   ⊢ 𝐺 = ⟨𝑉, 𝐸⟩    ⇒   ⊢ (𝐾 ∈ ({0, 1, 2} ∪ {3, 4, 5}) → (𝐺 NeighbVtx 𝐾) = {𝑛 ∈ ({0, 1, 2} ∪ {3, 4, 5}) ∣ {𝐾, 𝑛} ∈ ({{0, 3}} ∪ ({{0, 1}, {1, 2}, {2, 3}} ∪ {{3, 4}, {4, 5}, {0, 5}}))})
Theorem	usgrexmpl2nb0 48273	The neighborhood of the first vertex of graph 𝐺. (Contributed by AV, 9-Aug-2025.)
⊢ 𝑉 = (0...5)    &   ⊢ 𝐸 = ⟨“{0, 1} {1, 2} {2, 3} {3, 4} {4, 5} {0, 3} {0, 5}”⟩    &   ⊢ 𝐺 = ⟨𝑉, 𝐸⟩    ⇒   ⊢ (𝐺 NeighbVtx 0) = {1, 3, 5}
Theorem	usgrexmpl2nb1 48274	The neighborhood of the second vertex of graph 𝐺. (Contributed by AV, 9-Aug-2025.)
⊢ 𝑉 = (0...5)    &   ⊢ 𝐸 = ⟨“{0, 1} {1, 2} {2, 3} {3, 4} {4, 5} {0, 3} {0, 5}”⟩    &   ⊢ 𝐺 = ⟨𝑉, 𝐸⟩    ⇒   ⊢ (𝐺 NeighbVtx 1) = {0, 2}
Theorem	usgrexmpl2nb2 48275	The neighborhood of the third vertex of graph 𝐺. (Contributed by AV, 9-Aug-2025.)
⊢ 𝑉 = (0...5)    &   ⊢ 𝐸 = ⟨“{0, 1} {1, 2} {2, 3} {3, 4} {4, 5} {0, 3} {0, 5}”⟩    &   ⊢ 𝐺 = ⟨𝑉, 𝐸⟩    ⇒   ⊢ (𝐺 NeighbVtx 2) = {1, 3}
Theorem	usgrexmpl2nb3 48276	The neighborhood of the forth vertex of graph 𝐺. (Contributed by AV, 9-Aug-2025.)
⊢ 𝑉 = (0...5)    &   ⊢ 𝐸 = ⟨“{0, 1} {1, 2} {2, 3} {3, 4} {4, 5} {0, 3} {0, 5}”⟩    &   ⊢ 𝐺 = ⟨𝑉, 𝐸⟩    ⇒   ⊢ (𝐺 NeighbVtx 3) = {0, 2, 4}
Theorem	usgrexmpl2nb4 48277	The neighborhood of the fifth vertex of graph 𝐺. (Contributed by AV, 9-Aug-2025.)
⊢ 𝑉 = (0...5)    &   ⊢ 𝐸 = ⟨“{0, 1} {1, 2} {2, 3} {3, 4} {4, 5} {0, 3} {0, 5}”⟩    &   ⊢ 𝐺 = ⟨𝑉, 𝐸⟩    ⇒   ⊢ (𝐺 NeighbVtx 4) = {3, 5}
Theorem	usgrexmpl2nb5 48278	The neighborhood of the sixth vertex of graph 𝐺. (Contributed by AV, 10-Aug-2025.)
⊢ 𝑉 = (0...5)    &   ⊢ 𝐸 = ⟨“{0, 1} {1, 2} {2, 3} {3, 4} {4, 5} {0, 3} {0, 5}”⟩    &   ⊢ 𝐺 = ⟨𝑉, 𝐸⟩    ⇒   ⊢ (𝐺 NeighbVtx 5) = {0, 4}
Theorem	usgrexmpl2trifr 48279*	𝐺 is triangle-free. (Contributed by AV, 10-Aug-2025.)
⊢ 𝑉 = (0...5)    &   ⊢ 𝐸 = ⟨“{0, 1} {1, 2} {2, 3} {3, 4} {4, 5} {0, 3} {0, 5}”⟩    &   ⊢ 𝐺 = ⟨𝑉, 𝐸⟩    ⇒   ⊢ ¬ ∃𝑡 𝑡 ∈ (GrTriangles‘𝐺)
Theorem	usgrexmpl12ngric 48280	The graphs 𝐻 and 𝐺 are not isomorphic (𝐻 contains a triangle, see usgrexmpl1tri 48267, whereas 𝐺 does not, see usgrexmpl2trifr 48279. (Contributed by AV, 10-Aug-2025.)
⊢ 𝑉 = (0...5)    &   ⊢ 𝐸 = ⟨“{0, 1} {1, 2} {2, 3} {3, 4} {4, 5} {0, 3} {0, 5}”⟩    &   ⊢ 𝐺 = ⟨𝑉, 𝐸⟩    &   ⊢ 𝐾 = ⟨“{0, 1} {0, 2} {1, 2} {0, 3} {3, 4} {3, 5} {4, 5}”⟩    &   ⊢ 𝐻 = ⟨𝑉, 𝐾⟩    ⇒   ⊢ ¬ 𝐺 ≃𝑔𝑟 𝐻
Theorem	usgrexmpl12ngrlic 48281	The graphs 𝐻 and 𝐺 are not locally isomorphic (𝐻 contains a triangle, see usgrexmpl1tri 48267, whereas 𝐺 does not, see usgrexmpl2trifr 48279. (Contributed by AV, 24-Aug-2025.)
⊢ 𝑉 = (0...5)    &   ⊢ 𝐸 = ⟨“{0, 1} {1, 2} {2, 3} {3, 4} {4, 5} {0, 3} {0, 5}”⟩    &   ⊢ 𝐺 = ⟨𝑉, 𝐸⟩    &   ⊢ 𝐾 = ⟨“{0, 1} {0, 2} {1, 2} {0, 3} {3, 4} {3, 5} {4, 5}”⟩    &   ⊢ 𝐻 = ⟨𝑉, 𝐾⟩    ⇒   ⊢ ¬ 𝐺 ≃𝑙𝑔𝑟 𝐻
21.48.15.8  Generalized Petersen graphs According to Wikipedia "Generalized Petersen graph", 26-Aug-2025, https://en.wikipedia.org/wiki/Generalized_Petersen_graph: "In graph theory, the generalized Petersen graphs are a family of cubic graphs formed by connecting the vertices of a regular polygon to the corresponding vertices of a star polygon. They include the Petersen graph and generalize one of the ways of constructing the Petersen graph. ... Among the generalized Petersen graphs are the n-prism, ...". The vertices of the regular polygon are called "outside vertices", the vertices of the star polygon "inside vertices" (see A. Steimle, W. Stanton, "The isomorphism classes of the generalized Petersen graphs", Discrete Mathematics Volume 309, Issue 1, 6 January 2009, Pages 231-237: https://doi.org/10.1016/j.disc.2007.12.074). Since regular polygons are also considered as star polygons (with density 1), many theorems for "inside vertices" (with labels containing the fragment "vtx1") can be specialized for "outside vertices" (with labels containing the fragment "vtx0").
Syntax	cgpg 48282	Extend class notation with generalized Petersen graphs.
class gPetersenGr
Definition	df-gpg 48283*	Definition of generalized Petersen graphs according to Wikipedia "Generalized Petersen graph", 26-Aug-2025, https://en.wikipedia.org/wiki/Generalized_Petersen_graph: "In Watkins' notation, 𝐺(𝑛, 𝑘) is a graph with vertex set { u0, u1, ... , un-1, v0, v1, ... , vn-1 } and edge set { ui ui+1 , ui vi , vi vi+k | 0 ≤ 𝑖 ≤ (𝑛 − 1) } where subscripts are to be read modulo n and where 𝑘 < (𝑛 / 2). Some authors use the notation GPG(n,k)." Instead of 𝑛 ∈ ℕ, we could restrict the first argument to 𝑛 ∈ (ℤ≥‘3) (i.e., 3 ≤ 𝑛), because for 𝑛 ≤ 2, the definition is not meaningful (since then (⌈‘(𝑛 / 2)) ≤ 1 and therefore (1..^(⌈‘(𝑛 / 2))) = ∅, so that there would be no fitting second argument). (Contributed by AV, 26-Aug-2025.)
⊢ gPetersenGr = (𝑛 ∈ ℕ, 𝑘 ∈ (1..^(⌈‘(𝑛 / 2))) ↦ {⟨(Base‘ndx), ({0, 1} × (0..^𝑛))⟩, ⟨(.ef‘ndx), ( I ↾ {𝑒 ∈ 𝒫 ({0, 1} × (0..^𝑛)) ∣ ∃𝑥 ∈ (0..^𝑛)(𝑒 = {⟨0, 𝑥⟩, ⟨0, ((𝑥 + 1) mod 𝑛)⟩} ∨ 𝑒 = {⟨0, 𝑥⟩, ⟨1, 𝑥⟩} ∨ 𝑒 = {⟨1, 𝑥⟩, ⟨1, ((𝑥 + 𝑘) mod 𝑛)⟩})})⟩})
Theorem	gpgov 48284*	The generalized Petersen graph GPG(N,K). (Contributed by AV, 26-Aug-2025.)
⊢ 𝐽 = (1..^(⌈‘(𝑁 / 2)))    &   ⊢ 𝐼 = (0..^𝑁)    ⇒   ⊢ ((𝑁 ∈ ℕ ∧ 𝐾 ∈ 𝐽) → (𝑁 gPetersenGr 𝐾) = {⟨(Base‘ndx), ({0, 1} × 𝐼)⟩, ⟨(.ef‘ndx), ( I ↾ {𝑒 ∈ 𝒫 ({0, 1} × 𝐼) ∣ ∃𝑥 ∈ 𝐼 (𝑒 = {⟨0, 𝑥⟩, ⟨0, ((𝑥 + 1) mod 𝑁)⟩} ∨ 𝑒 = {⟨0, 𝑥⟩, ⟨1, 𝑥⟩} ∨ 𝑒 = {⟨1, 𝑥⟩, ⟨1, ((𝑥 + 𝐾) mod 𝑁)⟩})})⟩})
Theorem	gpgvtx 48285	The vertices of the generalized Petersen graph GPG(N,K). (Contributed by AV, 26-Aug-2025.)
⊢ 𝐽 = (1..^(⌈‘(𝑁 / 2)))    &   ⊢ 𝐼 = (0..^𝑁)    ⇒   ⊢ ((𝑁 ∈ ℕ ∧ 𝐾 ∈ 𝐽) → (Vtx‘(𝑁 gPetersenGr 𝐾)) = ({0, 1} × 𝐼))
Theorem	gpgiedg 48286*	The indexed edges of the generalized Petersen graph GPG(N,K). (Contributed by AV, 26-Aug-2025.)
⊢ 𝐽 = (1..^(⌈‘(𝑁 / 2)))    &   ⊢ 𝐼 = (0..^𝑁)    ⇒   ⊢ ((𝑁 ∈ ℕ ∧ 𝐾 ∈ 𝐽) → (iEdg‘(𝑁 gPetersenGr 𝐾)) = ( I ↾ {𝑒 ∈ 𝒫 ({0, 1} × 𝐼) ∣ ∃𝑥 ∈ 𝐼 (𝑒 = {⟨0, 𝑥⟩, ⟨0, ((𝑥 + 1) mod 𝑁)⟩} ∨ 𝑒 = {⟨0, 𝑥⟩, ⟨1, 𝑥⟩} ∨ 𝑒 = {⟨1, 𝑥⟩, ⟨1, ((𝑥 + 𝐾) mod 𝑁)⟩})}))
Theorem	gpgedg 48287*	The edges of the generalized Petersen graph GPG(N,K). (Contributed by AV, 26-Aug-2025.)
⊢ 𝐽 = (1..^(⌈‘(𝑁 / 2)))    &   ⊢ 𝐼 = (0..^𝑁)    ⇒   ⊢ ((𝑁 ∈ ℕ ∧ 𝐾 ∈ 𝐽) → (Edg‘(𝑁 gPetersenGr 𝐾)) = {𝑒 ∈ 𝒫 ({0, 1} × 𝐼) ∣ ∃𝑥 ∈ 𝐼 (𝑒 = {⟨0, 𝑥⟩, ⟨0, ((𝑥 + 1) mod 𝑁)⟩} ∨ 𝑒 = {⟨0, 𝑥⟩, ⟨1, 𝑥⟩} ∨ 𝑒 = {⟨1, 𝑥⟩, ⟨1, ((𝑥 + 𝐾) mod 𝑁)⟩})})
Theorem	gpgiedgdmellem 48288*	Lemma for gpgiedgdmel 48291 and gpgedgel 48292. (Contributed by AV, 2-Nov-2025.)
⊢ 𝐼 = (0..^𝑁)    &   ⊢ 𝐽 = (1..^(⌈‘(𝑁 / 2)))    ⇒   ⊢ ((𝑁 ∈ ℕ ∧ 𝐾 ∈ 𝐽) → (∃𝑥 ∈ 𝐼 (𝑌 = {⟨0, 𝑥⟩, ⟨0, ((𝑥 + 1) mod 𝑁)⟩} ∨ 𝑌 = {⟨0, 𝑥⟩, ⟨1, 𝑥⟩} ∨ 𝑌 = {⟨1, 𝑥⟩, ⟨1, ((𝑥 + 𝐾) mod 𝑁)⟩}) → 𝑌 ∈ 𝒫 ({0, 1} × 𝐼)))
Theorem	gpgvtxel 48289*	A vertex in a generalized Petersen graph 𝐺. (Contributed by AV, 29-Aug-2025.)
⊢ 𝐼 = (0..^𝑁)    &   ⊢ 𝐽 = (1..^(⌈‘(𝑁 / 2)))    &   ⊢ 𝐺 = (𝑁 gPetersenGr 𝐾)    &   ⊢ 𝑉 = (Vtx‘𝐺)    ⇒   ⊢ ((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) → (𝑋 ∈ 𝑉 ↔ ∃𝑥 ∈ {0, 1}∃𝑦 ∈ 𝐼 𝑋 = ⟨𝑥, 𝑦⟩))
Theorem	gpgvtxel2 48290	The second component of a vertex in a generalized Petersen graph 𝐺. (Contributed by AV, 30-Aug-2025.)
⊢ 𝐼 = (0..^𝑁)    &   ⊢ 𝐽 = (1..^(⌈‘(𝑁 / 2)))    &   ⊢ 𝐺 = (𝑁 gPetersenGr 𝐾)    &   ⊢ 𝑉 = (Vtx‘𝐺)    ⇒   ⊢ (((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) ∧ 𝑋 ∈ 𝑉) → (2nd ‘𝑋) ∈ 𝐼)
Theorem	gpgiedgdmel 48291*	An index of edges of the generalized Petersen graph GPG(N,K). (Contributed by AV, 2-Nov-2025.)
⊢ 𝐼 = (0..^𝑁)    &   ⊢ 𝐽 = (1..^(⌈‘(𝑁 / 2)))    &   ⊢ 𝐺 = (𝑁 gPetersenGr 𝐾)    ⇒   ⊢ ((𝑁 ∈ ℕ ∧ 𝐾 ∈ 𝐽) → (𝑋 ∈ dom (iEdg‘𝐺) ↔ ∃𝑥 ∈ 𝐼 (𝑋 = {⟨0, 𝑥⟩, ⟨0, ((𝑥 + 1) mod 𝑁)⟩} ∨ 𝑋 = {⟨0, 𝑥⟩, ⟨1, 𝑥⟩} ∨ 𝑋 = {⟨1, 𝑥⟩, ⟨1, ((𝑥 + 𝐾) mod 𝑁)⟩})))
Theorem	gpgedgel 48292*	An edge in a generalized Petersen graph 𝐺. (Contributed by AV, 29-Aug-2025.) (Proof shortened by AV, 8-Nov-2025.)
⊢ 𝐼 = (0..^𝑁)    &   ⊢ 𝐽 = (1..^(⌈‘(𝑁 / 2)))    &   ⊢ 𝐺 = (𝑁 gPetersenGr 𝐾)    &   ⊢ 𝐸 = (Edg‘𝐺)    ⇒   ⊢ ((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) → (𝑌 ∈ 𝐸 ↔ ∃𝑥 ∈ 𝐼 (𝑌 = {⟨0, 𝑥⟩, ⟨0, ((𝑥 + 1) mod 𝑁)⟩} ∨ 𝑌 = {⟨0, 𝑥⟩, ⟨1, 𝑥⟩} ∨ 𝑌 = {⟨1, 𝑥⟩, ⟨1, ((𝑥 + 𝐾) mod 𝑁)⟩})))
Theorem	gpgprismgriedgdmel 48293*	An index of edges of the generalized Petersen graph GPG(N,1). (Contributed by AV, 2-Nov-2025.)
⊢ 𝐼 = (0..^𝑁)    &   ⊢ 𝐺 = (𝑁 gPetersenGr 1)    ⇒   ⊢ (𝑁 ∈ (ℤ≥‘3) → (𝑋 ∈ dom (iEdg‘𝐺) ↔ ∃𝑥 ∈ 𝐼 (𝑋 = {⟨0, 𝑥⟩, ⟨0, ((𝑥 + 1) mod 𝑁)⟩} ∨ 𝑋 = {⟨0, 𝑥⟩, ⟨1, 𝑥⟩} ∨ 𝑋 = {⟨1, 𝑥⟩, ⟨1, ((𝑥 + 1) mod 𝑁)⟩})))
Theorem	gpgprismgriedgdmss 48294	A subset of the index of edges of the generalized Petersen graph GPG(N,1). (Contributed by AV, 2-Nov-2025.)
⊢ (𝑁 ∈ (ℤ≥‘3) → ({{⟨0, 0⟩, ⟨0, 1⟩}, {⟨0, 0⟩, ⟨1, 0⟩}} ∪ {{⟨1, 1⟩, ⟨0, 1⟩}, {⟨1, 1⟩, ⟨1, 0⟩}}) ⊆ dom (iEdg‘(𝑁 gPetersenGr 1)))
Theorem	gpgvtx0 48295	The outside vertices in a generalized Petersen graph 𝐺. (Contributed by AV, 30-Aug-2025.)
⊢ 𝐽 = (1..^(⌈‘(𝑁 / 2)))    &   ⊢ 𝐺 = (𝑁 gPetersenGr 𝐾)    &   ⊢ 𝑉 = (Vtx‘𝐺)    ⇒   ⊢ (((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) ∧ 𝑋 ∈ 𝑉) → (⟨0, (((2nd ‘𝑋) + 1) mod 𝑁)⟩ ∈ 𝑉 ∧ ⟨0, (2nd ‘𝑋)⟩ ∈ 𝑉 ∧ ⟨0, (((2nd ‘𝑋) − 1) mod 𝑁)⟩ ∈ 𝑉))
Theorem	gpgvtx1 48296	The inside vertices in a generalized Petersen graph 𝐺. (Contributed by AV, 28-Aug-2025.)
⊢ 𝐽 = (1..^(⌈‘(𝑁 / 2)))    &   ⊢ 𝐺 = (𝑁 gPetersenGr 𝐾)    &   ⊢ 𝑉 = (Vtx‘𝐺)    ⇒   ⊢ (((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) ∧ 𝑋 ∈ 𝑉) → (⟨1, (((2nd ‘𝑋) + 𝐾) mod 𝑁)⟩ ∈ 𝑉 ∧ ⟨1, (2nd ‘𝑋)⟩ ∈ 𝑉 ∧ ⟨1, (((2nd ‘𝑋) − 𝐾) mod 𝑁)⟩ ∈ 𝑉))
Theorem	opgpgvtx 48297	A vertex in a generalized Petersen graph 𝐺 as ordered pair. (Contributed by AV, 1-Oct-2025.)
⊢ 𝐼 = (0..^𝑁)    &   ⊢ 𝐽 = (1..^(⌈‘(𝑁 / 2)))    &   ⊢ 𝐺 = (𝑁 gPetersenGr 𝐾)    &   ⊢ 𝑉 = (Vtx‘𝐺)    ⇒   ⊢ ((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) → (⟨𝑋, 𝑌⟩ ∈ 𝑉 ↔ ((𝑋 = 0 ∨ 𝑋 = 1) ∧ 𝑌 ∈ 𝐼)))
Theorem	gpgusgralem 48298*	Lemma for gpgusgra 48299. (Contributed by AV, 27-Aug-2025.) (Proof shortened by AV, 6-Sep-2025.)
⊢ 𝐽 = (1..^(⌈‘(𝑁 / 2)))    &   ⊢ 𝐼 = (0..^𝑁)    ⇒   ⊢ ((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ 𝐽) → {𝑒 ∈ 𝒫 ({0, 1} × 𝐼) ∣ ∃𝑥 ∈ 𝐼 (𝑒 = {⟨0, 𝑥⟩, ⟨0, ((𝑥 + 1) mod 𝑁)⟩} ∨ 𝑒 = {⟨0, 𝑥⟩, ⟨1, 𝑥⟩} ∨ 𝑒 = {⟨1, 𝑥⟩, ⟨1, ((𝑥 + 𝐾) mod 𝑁)⟩})} ⊆ {𝑝 ∈ 𝒫 ({0, 1} × 𝐼) ∣ (♯‘𝑝) = 2})
Theorem	gpgusgra 48299	The generalized Petersen graph GPG(N,K) is a simple graph. (Contributed by AV, 27-Aug-2025.)
⊢ ((𝑁 ∈ (ℤ≥‘3) ∧ 𝐾 ∈ (1..^(⌈‘(𝑁 / 2)))) → (𝑁 gPetersenGr 𝐾) ∈ USGraph)
Theorem	gpgprismgrusgra 48300	The generalized Petersen graphs G(N,1), which are the N-prisms, are simple graphs. (Contributed by AV, 31-Oct-2025.)
⊢ (𝑁 ∈ (ℤ≥‘3) → (𝑁 gPetersenGr 1) ∈ USGraph)