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Theorem usgr2pth 40970
 Description: In a simple graph, there is a path of length 2 iff there are three distinct vertices so that one of them is connected to each of the two others by an edge. (Contributed by Alexander van der Vekens, 27-Jan-2018.) (Revised by AV, 5-Jun-2021.)
Hypotheses
Ref Expression
usgr2pthlem.v 𝑉 = (Vtx‘𝐺)
usgr2pthlem.i 𝐼 = (iEdg‘𝐺)
Assertion
Ref Expression
usgr2pth (𝐺 ∈ USGraph → ((𝐹(PathS‘𝐺)𝑃 ∧ (#‘𝐹) = 2) ↔ (𝐹:(0..^2)–1-1→dom 𝐼𝑃:(0...2)–1-1𝑉 ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧})))))
Distinct variable groups:   𝑥,𝐹,𝑦,𝑧   𝑥,𝐺,𝑦,𝑧   𝑥,𝐼,𝑦,𝑧   𝑥,𝑃,𝑦,𝑧   𝑥,𝑉,𝑦,𝑧

Proof of Theorem usgr2pth
Dummy variable 𝑖 is distinct from all other variables.
StepHypRef Expression
1 usgr2pthspth 40968 . . . . . . 7 ((𝐺 ∈ USGraph ∧ (#‘𝐹) = 2) → (𝐹(PathS‘𝐺)𝑃𝐹(SPathS‘𝐺)𝑃))
2 usgrupgr 40412 . . . . . . . . . . . 12 (𝐺 ∈ USGraph → 𝐺 ∈ UPGraph )
32adantr 480 . . . . . . . . . . 11 ((𝐺 ∈ USGraph ∧ (#‘𝐹) = 2) → 𝐺 ∈ UPGraph )
4 sPthis1wlk 40934 . . . . . . . . . . . 12 (𝐹(SPathS‘𝐺)𝑃𝐹(1Walks‘𝐺)𝑃)
5 wlkv 40815 . . . . . . . . . . . . 13 (𝐹(1Walks‘𝐺)𝑃 → (𝐺 ∈ V ∧ 𝐹 ∈ V ∧ 𝑃 ∈ V))
6 3simpc 1053 . . . . . . . . . . . . 13 ((𝐺 ∈ V ∧ 𝐹 ∈ V ∧ 𝑃 ∈ V) → (𝐹 ∈ V ∧ 𝑃 ∈ V))
75, 6syl 17 . . . . . . . . . . . 12 (𝐹(1Walks‘𝐺)𝑃 → (𝐹 ∈ V ∧ 𝑃 ∈ V))
84, 7syl 17 . . . . . . . . . . 11 (𝐹(SPathS‘𝐺)𝑃 → (𝐹 ∈ V ∧ 𝑃 ∈ V))
93, 8anim12i 588 . . . . . . . . . 10 (((𝐺 ∈ USGraph ∧ (#‘𝐹) = 2) ∧ 𝐹(SPathS‘𝐺)𝑃) → (𝐺 ∈ UPGraph ∧ (𝐹 ∈ V ∧ 𝑃 ∈ V)))
10 3anass 1035 . . . . . . . . . 10 ((𝐺 ∈ UPGraph ∧ 𝐹 ∈ V ∧ 𝑃 ∈ V) ↔ (𝐺 ∈ UPGraph ∧ (𝐹 ∈ V ∧ 𝑃 ∈ V)))
119, 10sylibr 223 . . . . . . . . 9 (((𝐺 ∈ USGraph ∧ (#‘𝐹) = 2) ∧ 𝐹(SPathS‘𝐺)𝑃) → (𝐺 ∈ UPGraph ∧ 𝐹 ∈ V ∧ 𝑃 ∈ V))
12 issPth 40930 . . . . . . . . . . . 12 ((𝐺 ∈ UPGraph ∧ 𝐹 ∈ V ∧ 𝑃 ∈ V) → (𝐹(SPathS‘𝐺)𝑃 ↔ (𝐹(TrailS‘𝐺)𝑃 ∧ Fun 𝑃)))
13 usgr2pthlem.v . . . . . . . . . . . . . . 15 𝑉 = (Vtx‘𝐺)
14 usgr2pthlem.i . . . . . . . . . . . . . . 15 𝐼 = (iEdg‘𝐺)
1513, 14upgrf1istrl 40911 . . . . . . . . . . . . . 14 ((𝐺 ∈ UPGraph ∧ 𝐹 ∈ V ∧ 𝑃 ∈ V) → (𝐹(TrailS‘𝐺)𝑃 ↔ (𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼𝑃:(0...(#‘𝐹))⟶𝑉 ∧ ∀𝑖 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹𝑖)) = {(𝑃𝑖), (𝑃‘(𝑖 + 1))})))
1615anbi1d 737 . . . . . . . . . . . . 13 ((𝐺 ∈ UPGraph ∧ 𝐹 ∈ V ∧ 𝑃 ∈ V) → ((𝐹(TrailS‘𝐺)𝑃 ∧ Fun 𝑃) ↔ ((𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼𝑃:(0...(#‘𝐹))⟶𝑉 ∧ ∀𝑖 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹𝑖)) = {(𝑃𝑖), (𝑃‘(𝑖 + 1))}) ∧ Fun 𝑃)))
17 oveq2 6557 . . . . . . . . . . . . . . . . . . . . 21 ((#‘𝐹) = 2 → (0..^(#‘𝐹)) = (0..^2))
18 f1eq2 6010 . . . . . . . . . . . . . . . . . . . . 21 ((0..^(#‘𝐹)) = (0..^2) → (𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼𝐹:(0..^2)–1-1→dom 𝐼))
1917, 18syl 17 . . . . . . . . . . . . . . . . . . . 20 ((#‘𝐹) = 2 → (𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼𝐹:(0..^2)–1-1→dom 𝐼))
2019biimpd 218 . . . . . . . . . . . . . . . . . . 19 ((#‘𝐹) = 2 → (𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼𝐹:(0..^2)–1-1→dom 𝐼))
2120adantl 481 . . . . . . . . . . . . . . . . . 18 ((𝐺 ∈ USGraph ∧ (#‘𝐹) = 2) → (𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼𝐹:(0..^2)–1-1→dom 𝐼))
2221com12 32 . . . . . . . . . . . . . . . . 17 (𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼 → ((𝐺 ∈ USGraph ∧ (#‘𝐹) = 2) → 𝐹:(0..^2)–1-1→dom 𝐼))
23223ad2ant1 1075 . . . . . . . . . . . . . . . 16 ((𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼𝑃:(0...(#‘𝐹))⟶𝑉 ∧ ∀𝑖 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹𝑖)) = {(𝑃𝑖), (𝑃‘(𝑖 + 1))}) → ((𝐺 ∈ USGraph ∧ (#‘𝐹) = 2) → 𝐹:(0..^2)–1-1→dom 𝐼))
2423ad2antrl 760 . . . . . . . . . . . . . . 15 (((𝐺 ∈ UPGraph ∧ 𝐹 ∈ V ∧ 𝑃 ∈ V) ∧ ((𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼𝑃:(0...(#‘𝐹))⟶𝑉 ∧ ∀𝑖 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹𝑖)) = {(𝑃𝑖), (𝑃‘(𝑖 + 1))}) ∧ Fun 𝑃)) → ((𝐺 ∈ USGraph ∧ (#‘𝐹) = 2) → 𝐹:(0..^2)–1-1→dom 𝐼))
25 oveq2 6557 . . . . . . . . . . . . . . . . . . . . . 22 ((#‘𝐹) = 2 → (0...(#‘𝐹)) = (0...2))
2625feq2d 5944 . . . . . . . . . . . . . . . . . . . . 21 ((#‘𝐹) = 2 → (𝑃:(0...(#‘𝐹))⟶𝑉𝑃:(0...2)⟶𝑉))
27 df-f1 5809 . . . . . . . . . . . . . . . . . . . . . . 23 (𝑃:(0...2)–1-1𝑉 ↔ (𝑃:(0...2)⟶𝑉 ∧ Fun 𝑃))
2827simplbi2 653 . . . . . . . . . . . . . . . . . . . . . 22 (𝑃:(0...2)⟶𝑉 → (Fun 𝑃𝑃:(0...2)–1-1𝑉))
2928a1i 11 . . . . . . . . . . . . . . . . . . . . 21 ((#‘𝐹) = 2 → (𝑃:(0...2)⟶𝑉 → (Fun 𝑃𝑃:(0...2)–1-1𝑉)))
3026, 29sylbid 229 . . . . . . . . . . . . . . . . . . . 20 ((#‘𝐹) = 2 → (𝑃:(0...(#‘𝐹))⟶𝑉 → (Fun 𝑃𝑃:(0...2)–1-1𝑉)))
3130adantl 481 . . . . . . . . . . . . . . . . . . 19 ((𝐺 ∈ USGraph ∧ (#‘𝐹) = 2) → (𝑃:(0...(#‘𝐹))⟶𝑉 → (Fun 𝑃𝑃:(0...2)–1-1𝑉)))
3231com3l 87 . . . . . . . . . . . . . . . . . 18 (𝑃:(0...(#‘𝐹))⟶𝑉 → (Fun 𝑃 → ((𝐺 ∈ USGraph ∧ (#‘𝐹) = 2) → 𝑃:(0...2)–1-1𝑉)))
33323ad2ant2 1076 . . . . . . . . . . . . . . . . 17 ((𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼𝑃:(0...(#‘𝐹))⟶𝑉 ∧ ∀𝑖 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹𝑖)) = {(𝑃𝑖), (𝑃‘(𝑖 + 1))}) → (Fun 𝑃 → ((𝐺 ∈ USGraph ∧ (#‘𝐹) = 2) → 𝑃:(0...2)–1-1𝑉)))
3433imp 444 . . . . . . . . . . . . . . . 16 (((𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼𝑃:(0...(#‘𝐹))⟶𝑉 ∧ ∀𝑖 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹𝑖)) = {(𝑃𝑖), (𝑃‘(𝑖 + 1))}) ∧ Fun 𝑃) → ((𝐺 ∈ USGraph ∧ (#‘𝐹) = 2) → 𝑃:(0...2)–1-1𝑉))
3534adantl 481 . . . . . . . . . . . . . . 15 (((𝐺 ∈ UPGraph ∧ 𝐹 ∈ V ∧ 𝑃 ∈ V) ∧ ((𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼𝑃:(0...(#‘𝐹))⟶𝑉 ∧ ∀𝑖 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹𝑖)) = {(𝑃𝑖), (𝑃‘(𝑖 + 1))}) ∧ Fun 𝑃)) → ((𝐺 ∈ USGraph ∧ (#‘𝐹) = 2) → 𝑃:(0...2)–1-1𝑉))
3613, 14usgr2pthlem 40969 . . . . . . . . . . . . . . . 16 ((𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼𝑃:(0...(#‘𝐹))⟶𝑉 ∧ ∀𝑖 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹𝑖)) = {(𝑃𝑖), (𝑃‘(𝑖 + 1))}) → ((𝐺 ∈ USGraph ∧ (#‘𝐹) = 2) → ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))))
3736ad2antrl 760 . . . . . . . . . . . . . . 15 (((𝐺 ∈ UPGraph ∧ 𝐹 ∈ V ∧ 𝑃 ∈ V) ∧ ((𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼𝑃:(0...(#‘𝐹))⟶𝑉 ∧ ∀𝑖 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹𝑖)) = {(𝑃𝑖), (𝑃‘(𝑖 + 1))}) ∧ Fun 𝑃)) → ((𝐺 ∈ USGraph ∧ (#‘𝐹) = 2) → ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))))
3824, 35, 373jcad 1236 . . . . . . . . . . . . . 14 (((𝐺 ∈ UPGraph ∧ 𝐹 ∈ V ∧ 𝑃 ∈ V) ∧ ((𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼𝑃:(0...(#‘𝐹))⟶𝑉 ∧ ∀𝑖 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹𝑖)) = {(𝑃𝑖), (𝑃‘(𝑖 + 1))}) ∧ Fun 𝑃)) → ((𝐺 ∈ USGraph ∧ (#‘𝐹) = 2) → (𝐹:(0..^2)–1-1→dom 𝐼𝑃:(0...2)–1-1𝑉 ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧})))))
3938ex 449 . . . . . . . . . . . . 13 ((𝐺 ∈ UPGraph ∧ 𝐹 ∈ V ∧ 𝑃 ∈ V) → (((𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼𝑃:(0...(#‘𝐹))⟶𝑉 ∧ ∀𝑖 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹𝑖)) = {(𝑃𝑖), (𝑃‘(𝑖 + 1))}) ∧ Fun 𝑃) → ((𝐺 ∈ USGraph ∧ (#‘𝐹) = 2) → (𝐹:(0..^2)–1-1→dom 𝐼𝑃:(0...2)–1-1𝑉 ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))))))
4016, 39sylbid 229 . . . . . . . . . . . 12 ((𝐺 ∈ UPGraph ∧ 𝐹 ∈ V ∧ 𝑃 ∈ V) → ((𝐹(TrailS‘𝐺)𝑃 ∧ Fun 𝑃) → ((𝐺 ∈ USGraph ∧ (#‘𝐹) = 2) → (𝐹:(0..^2)–1-1→dom 𝐼𝑃:(0...2)–1-1𝑉 ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))))))
4112, 40sylbid 229 . . . . . . . . . . 11 ((𝐺 ∈ UPGraph ∧ 𝐹 ∈ V ∧ 𝑃 ∈ V) → (𝐹(SPathS‘𝐺)𝑃 → ((𝐺 ∈ USGraph ∧ (#‘𝐹) = 2) → (𝐹:(0..^2)–1-1→dom 𝐼𝑃:(0...2)–1-1𝑉 ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))))))
4241com23 84 . . . . . . . . . 10 ((𝐺 ∈ UPGraph ∧ 𝐹 ∈ V ∧ 𝑃 ∈ V) → ((𝐺 ∈ USGraph ∧ (#‘𝐹) = 2) → (𝐹(SPathS‘𝐺)𝑃 → (𝐹:(0..^2)–1-1→dom 𝐼𝑃:(0...2)–1-1𝑉 ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))))))
4342impd 446 . . . . . . . . 9 ((𝐺 ∈ UPGraph ∧ 𝐹 ∈ V ∧ 𝑃 ∈ V) → (((𝐺 ∈ USGraph ∧ (#‘𝐹) = 2) ∧ 𝐹(SPathS‘𝐺)𝑃) → (𝐹:(0..^2)–1-1→dom 𝐼𝑃:(0...2)–1-1𝑉 ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧})))))
4411, 43mpcom 37 . . . . . . . 8 (((𝐺 ∈ USGraph ∧ (#‘𝐹) = 2) ∧ 𝐹(SPathS‘𝐺)𝑃) → (𝐹:(0..^2)–1-1→dom 𝐼𝑃:(0...2)–1-1𝑉 ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))))
4544ex 449 . . . . . . 7 ((𝐺 ∈ USGraph ∧ (#‘𝐹) = 2) → (𝐹(SPathS‘𝐺)𝑃 → (𝐹:(0..^2)–1-1→dom 𝐼𝑃:(0...2)–1-1𝑉 ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧})))))
461, 45sylbid 229 . . . . . 6 ((𝐺 ∈ USGraph ∧ (#‘𝐹) = 2) → (𝐹(PathS‘𝐺)𝑃 → (𝐹:(0..^2)–1-1→dom 𝐼𝑃:(0...2)–1-1𝑉 ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧})))))
4746ex 449 . . . . 5 (𝐺 ∈ USGraph → ((#‘𝐹) = 2 → (𝐹(PathS‘𝐺)𝑃 → (𝐹:(0..^2)–1-1→dom 𝐼𝑃:(0...2)–1-1𝑉 ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))))))
4847com13 86 . . . 4 (𝐹(PathS‘𝐺)𝑃 → ((#‘𝐹) = 2 → (𝐺 ∈ USGraph → (𝐹:(0..^2)–1-1→dom 𝐼𝑃:(0...2)–1-1𝑉 ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))))))
4948imp 444 . . 3 ((𝐹(PathS‘𝐺)𝑃 ∧ (#‘𝐹) = 2) → (𝐺 ∈ USGraph → (𝐹:(0..^2)–1-1→dom 𝐼𝑃:(0...2)–1-1𝑉 ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧})))))
5049com12 32 . 2 (𝐺 ∈ USGraph → ((𝐹(PathS‘𝐺)𝑃 ∧ (#‘𝐹) = 2) → (𝐹:(0..^2)–1-1→dom 𝐼𝑃:(0...2)–1-1𝑉 ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧})))))
51 2nn0 11186 . . . . . 6 2 ∈ ℕ0
52 f1f 6014 . . . . . 6 (𝐹:(0..^2)–1-1→dom 𝐼𝐹:(0..^2)⟶dom 𝐼)
53 fnfzo0hash 13091 . . . . . 6 ((2 ∈ ℕ0𝐹:(0..^2)⟶dom 𝐼) → (#‘𝐹) = 2)
5451, 52, 53sylancr 694 . . . . 5 (𝐹:(0..^2)–1-1→dom 𝐼 → (#‘𝐹) = 2)
55 oveq2 6557 . . . . . . . . . . . . . . . . . 18 (2 = (#‘𝐹) → (0..^2) = (0..^(#‘𝐹)))
5655eqcoms 2618 . . . . . . . . . . . . . . . . 17 ((#‘𝐹) = 2 → (0..^2) = (0..^(#‘𝐹)))
57 f1eq2 6010 . . . . . . . . . . . . . . . . 17 ((0..^2) = (0..^(#‘𝐹)) → (𝐹:(0..^2)–1-1→dom 𝐼𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼))
5856, 57syl 17 . . . . . . . . . . . . . . . 16 ((#‘𝐹) = 2 → (𝐹:(0..^2)–1-1→dom 𝐼𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼))
5958biimpd 218 . . . . . . . . . . . . . . 15 ((#‘𝐹) = 2 → (𝐹:(0..^2)–1-1→dom 𝐼𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼))
6059imp 444 . . . . . . . . . . . . . 14 (((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) → 𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼)
6160adantr 480 . . . . . . . . . . . . 13 ((((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) ∧ 𝑃:(0...2)–1-1𝑉) → 𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼)
6261ad2antrr 758 . . . . . . . . . . . 12 ((((((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) ∧ 𝑃:(0...2)–1-1𝑉) ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))) ∧ 𝐺 ∈ USGraph ) → 𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼)
63 f1f 6014 . . . . . . . . . . . . . . 15 (𝑃:(0...2)–1-1𝑉𝑃:(0...2)⟶𝑉)
64 oveq2 6557 . . . . . . . . . . . . . . . . . 18 (2 = (#‘𝐹) → (0...2) = (0...(#‘𝐹)))
6564eqcoms 2618 . . . . . . . . . . . . . . . . 17 ((#‘𝐹) = 2 → (0...2) = (0...(#‘𝐹)))
6665adantr 480 . . . . . . . . . . . . . . . 16 (((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) → (0...2) = (0...(#‘𝐹)))
6766feq2d 5944 . . . . . . . . . . . . . . 15 (((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) → (𝑃:(0...2)⟶𝑉𝑃:(0...(#‘𝐹))⟶𝑉))
6863, 67syl5ib 233 . . . . . . . . . . . . . 14 (((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) → (𝑃:(0...2)–1-1𝑉𝑃:(0...(#‘𝐹))⟶𝑉))
6968imp 444 . . . . . . . . . . . . 13 ((((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) ∧ 𝑃:(0...2)–1-1𝑉) → 𝑃:(0...(#‘𝐹))⟶𝑉)
7069ad2antrr 758 . . . . . . . . . . . 12 ((((((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) ∧ 𝑃:(0...2)–1-1𝑉) ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))) ∧ 𝐺 ∈ USGraph ) → 𝑃:(0...(#‘𝐹))⟶𝑉)
71 eqcom 2617 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 ((𝑃‘0) = 𝑥𝑥 = (𝑃‘0))
7271biimpi 205 . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 ((𝑃‘0) = 𝑥𝑥 = (𝑃‘0))
73723ad2ant1 1075 . . . . . . . . . . . . . . . . . . . . . . . . . . 27 (((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) → 𝑥 = (𝑃‘0))
74 eqcom 2617 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 ((𝑃‘1) = 𝑦𝑦 = (𝑃‘1))
7574biimpi 205 . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 ((𝑃‘1) = 𝑦𝑦 = (𝑃‘1))
76753ad2ant2 1076 . . . . . . . . . . . . . . . . . . . . . . . . . . 27 (((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) → 𝑦 = (𝑃‘1))
7773, 76preq12d 4220 . . . . . . . . . . . . . . . . . . . . . . . . . 26 (((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) → {𝑥, 𝑦} = {(𝑃‘0), (𝑃‘1)})
7877eqeq2d 2620 . . . . . . . . . . . . . . . . . . . . . . . . 25 (((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) → ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ↔ (𝐼‘(𝐹‘0)) = {(𝑃‘0), (𝑃‘1)}))
7978biimpd 218 . . . . . . . . . . . . . . . . . . . . . . . 24 (((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) → ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} → (𝐼‘(𝐹‘0)) = {(𝑃‘0), (𝑃‘1)}))
8079com12 32 . . . . . . . . . . . . . . . . . . . . . . 23 ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} → (((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) → (𝐼‘(𝐹‘0)) = {(𝑃‘0), (𝑃‘1)}))
8180adantr 480 . . . . . . . . . . . . . . . . . . . . . 22 (((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}) → (((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) → (𝐼‘(𝐹‘0)) = {(𝑃‘0), (𝑃‘1)}))
8281impcom 445 . . . . . . . . . . . . . . . . . . . . 21 ((((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧})) → (𝐼‘(𝐹‘0)) = {(𝑃‘0), (𝑃‘1)})
83 eqcom 2617 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 ((𝑃‘2) = 𝑧𝑧 = (𝑃‘2))
8483biimpi 205 . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 ((𝑃‘2) = 𝑧𝑧 = (𝑃‘2))
85843ad2ant3 1077 . . . . . . . . . . . . . . . . . . . . . . . . . . 27 (((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) → 𝑧 = (𝑃‘2))
8676, 85preq12d 4220 . . . . . . . . . . . . . . . . . . . . . . . . . 26 (((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) → {𝑦, 𝑧} = {(𝑃‘1), (𝑃‘2)})
8786eqeq2d 2620 . . . . . . . . . . . . . . . . . . . . . . . . 25 (((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) → ((𝐼‘(𝐹‘1)) = {𝑦, 𝑧} ↔ (𝐼‘(𝐹‘1)) = {(𝑃‘1), (𝑃‘2)}))
8887biimpd 218 . . . . . . . . . . . . . . . . . . . . . . . 24 (((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) → ((𝐼‘(𝐹‘1)) = {𝑦, 𝑧} → (𝐼‘(𝐹‘1)) = {(𝑃‘1), (𝑃‘2)}))
8988com12 32 . . . . . . . . . . . . . . . . . . . . . . 23 ((𝐼‘(𝐹‘1)) = {𝑦, 𝑧} → (((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) → (𝐼‘(𝐹‘1)) = {(𝑃‘1), (𝑃‘2)}))
9089adantl 481 . . . . . . . . . . . . . . . . . . . . . 22 (((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}) → (((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) → (𝐼‘(𝐹‘1)) = {(𝑃‘1), (𝑃‘2)}))
9190impcom 445 . . . . . . . . . . . . . . . . . . . . 21 ((((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧})) → (𝐼‘(𝐹‘1)) = {(𝑃‘1), (𝑃‘2)})
9282, 91jca 553 . . . . . . . . . . . . . . . . . . . 20 ((((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧})) → ((𝐼‘(𝐹‘0)) = {(𝑃‘0), (𝑃‘1)} ∧ (𝐼‘(𝐹‘1)) = {(𝑃‘1), (𝑃‘2)}))
9392rexlimivw 3011 . . . . . . . . . . . . . . . . . . 19 (∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧})) → ((𝐼‘(𝐹‘0)) = {(𝑃‘0), (𝑃‘1)} ∧ (𝐼‘(𝐹‘1)) = {(𝑃‘1), (𝑃‘2)}))
9493rexlimivw 3011 . . . . . . . . . . . . . . . . . 18 (∃𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧})) → ((𝐼‘(𝐹‘0)) = {(𝑃‘0), (𝑃‘1)} ∧ (𝐼‘(𝐹‘1)) = {(𝑃‘1), (𝑃‘2)}))
9594rexlimivw 3011 . . . . . . . . . . . . . . . . 17 (∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧})) → ((𝐼‘(𝐹‘0)) = {(𝑃‘0), (𝑃‘1)} ∧ (𝐼‘(𝐹‘1)) = {(𝑃‘1), (𝑃‘2)}))
9695a1i13 27 . . . . . . . . . . . . . . . 16 ((#‘𝐹) = 2 → (∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧})) → (𝐺 ∈ USGraph → ((𝐼‘(𝐹‘0)) = {(𝑃‘0), (𝑃‘1)} ∧ (𝐼‘(𝐹‘1)) = {(𝑃‘1), (𝑃‘2)}))))
97 fzo0to2pr 12420 . . . . . . . . . . . . . . . . . . . . 21 (0..^2) = {0, 1}
9817, 97syl6eq 2660 . . . . . . . . . . . . . . . . . . . 20 ((#‘𝐹) = 2 → (0..^(#‘𝐹)) = {0, 1})
9998raleqdv 3121 . . . . . . . . . . . . . . . . . . 19 ((#‘𝐹) = 2 → (∀𝑖 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹𝑖)) = {(𝑃𝑖), (𝑃‘(𝑖 + 1))} ↔ ∀𝑖 ∈ {0, 1} (𝐼‘(𝐹𝑖)) = {(𝑃𝑖), (𝑃‘(𝑖 + 1))}))
100 2wlklem 26094 . . . . . . . . . . . . . . . . . . 19 (∀𝑖 ∈ {0, 1} (𝐼‘(𝐹𝑖)) = {(𝑃𝑖), (𝑃‘(𝑖 + 1))} ↔ ((𝐼‘(𝐹‘0)) = {(𝑃‘0), (𝑃‘1)} ∧ (𝐼‘(𝐹‘1)) = {(𝑃‘1), (𝑃‘2)}))
10199, 100syl6bb 275 . . . . . . . . . . . . . . . . . 18 ((#‘𝐹) = 2 → (∀𝑖 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹𝑖)) = {(𝑃𝑖), (𝑃‘(𝑖 + 1))} ↔ ((𝐼‘(𝐹‘0)) = {(𝑃‘0), (𝑃‘1)} ∧ (𝐼‘(𝐹‘1)) = {(𝑃‘1), (𝑃‘2)})))
102101imbi2d 329 . . . . . . . . . . . . . . . . 17 ((#‘𝐹) = 2 → ((𝐺 ∈ USGraph → ∀𝑖 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹𝑖)) = {(𝑃𝑖), (𝑃‘(𝑖 + 1))}) ↔ (𝐺 ∈ USGraph → ((𝐼‘(𝐹‘0)) = {(𝑃‘0), (𝑃‘1)} ∧ (𝐼‘(𝐹‘1)) = {(𝑃‘1), (𝑃‘2)}))))
103102imbi2d 329 . . . . . . . . . . . . . . . 16 ((#‘𝐹) = 2 → ((∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧})) → (𝐺 ∈ USGraph → ∀𝑖 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹𝑖)) = {(𝑃𝑖), (𝑃‘(𝑖 + 1))})) ↔ (∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧})) → (𝐺 ∈ USGraph → ((𝐼‘(𝐹‘0)) = {(𝑃‘0), (𝑃‘1)} ∧ (𝐼‘(𝐹‘1)) = {(𝑃‘1), (𝑃‘2)})))))
10496, 103mpbird 246 . . . . . . . . . . . . . . 15 ((#‘𝐹) = 2 → (∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧})) → (𝐺 ∈ USGraph → ∀𝑖 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹𝑖)) = {(𝑃𝑖), (𝑃‘(𝑖 + 1))})))
105104ad2antrr 758 . . . . . . . . . . . . . 14 ((((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) ∧ 𝑃:(0...2)–1-1𝑉) → (∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧})) → (𝐺 ∈ USGraph → ∀𝑖 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹𝑖)) = {(𝑃𝑖), (𝑃‘(𝑖 + 1))})))
106105imp 444 . . . . . . . . . . . . 13 (((((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) ∧ 𝑃:(0...2)–1-1𝑉) ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))) → (𝐺 ∈ USGraph → ∀𝑖 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹𝑖)) = {(𝑃𝑖), (𝑃‘(𝑖 + 1))}))
107106imp 444 . . . . . . . . . . . 12 ((((((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) ∧ 𝑃:(0...2)–1-1𝑉) ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))) ∧ 𝐺 ∈ USGraph ) → ∀𝑖 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹𝑖)) = {(𝑃𝑖), (𝑃‘(𝑖 + 1))})
10862, 70, 1073jca 1235 . . . . . . . . . . 11 ((((((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) ∧ 𝑃:(0...2)–1-1𝑉) ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))) ∧ 𝐺 ∈ USGraph ) → (𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼𝑃:(0...(#‘𝐹))⟶𝑉 ∧ ∀𝑖 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹𝑖)) = {(𝑃𝑖), (𝑃‘(𝑖 + 1))}))
10927simprbi 479 . . . . . . . . . . . . 13 (𝑃:(0...2)–1-1𝑉 → Fun 𝑃)
110109adantl 481 . . . . . . . . . . . 12 ((((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) ∧ 𝑃:(0...2)–1-1𝑉) → Fun 𝑃)
111110ad2antrr 758 . . . . . . . . . . 11 ((((((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) ∧ 𝑃:(0...2)–1-1𝑉) ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))) ∧ 𝐺 ∈ USGraph ) → Fun 𝑃)
112108, 111jca 553 . . . . . . . . . 10 ((((((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) ∧ 𝑃:(0...2)–1-1𝑉) ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))) ∧ 𝐺 ∈ USGraph ) → ((𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼𝑃:(0...(#‘𝐹))⟶𝑉 ∧ ∀𝑖 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹𝑖)) = {(𝑃𝑖), (𝑃‘(𝑖 + 1))}) ∧ Fun 𝑃))
1132adantl 481 . . . . . . . . . . . . 13 ((((((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) ∧ 𝑃:(0...2)–1-1𝑉) ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))) ∧ 𝐺 ∈ USGraph ) → 𝐺 ∈ UPGraph )
114 ovex 6577 . . . . . . . . . . . . . . . . 17 (0..^2) ∈ V
115 fex 6394 . . . . . . . . . . . . . . . . 17 ((𝐹:(0..^2)⟶dom 𝐼 ∧ (0..^2) ∈ V) → 𝐹 ∈ V)
11652, 114, 115sylancl 693 . . . . . . . . . . . . . . . 16 (𝐹:(0..^2)–1-1→dom 𝐼𝐹 ∈ V)
117116adantl 481 . . . . . . . . . . . . . . 15 (((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) → 𝐹 ∈ V)
118 ovex 6577 . . . . . . . . . . . . . . . 16 (0...2) ∈ V
119 fex 6394 . . . . . . . . . . . . . . . 16 ((𝑃:(0...2)⟶𝑉 ∧ (0...2) ∈ V) → 𝑃 ∈ V)
12063, 118, 119sylancl 693 . . . . . . . . . . . . . . 15 (𝑃:(0...2)–1-1𝑉𝑃 ∈ V)
121117, 120anim12i 588 . . . . . . . . . . . . . 14 ((((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) ∧ 𝑃:(0...2)–1-1𝑉) → (𝐹 ∈ V ∧ 𝑃 ∈ V))
122121ad2antrr 758 . . . . . . . . . . . . 13 ((((((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) ∧ 𝑃:(0...2)–1-1𝑉) ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))) ∧ 𝐺 ∈ USGraph ) → (𝐹 ∈ V ∧ 𝑃 ∈ V))
123113, 122jca 553 . . . . . . . . . . . 12 ((((((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) ∧ 𝑃:(0...2)–1-1𝑉) ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))) ∧ 𝐺 ∈ USGraph ) → (𝐺 ∈ UPGraph ∧ (𝐹 ∈ V ∧ 𝑃 ∈ V)))
124123, 10sylibr 223 . . . . . . . . . . 11 ((((((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) ∧ 𝑃:(0...2)–1-1𝑉) ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))) ∧ 𝐺 ∈ USGraph ) → (𝐺 ∈ UPGraph ∧ 𝐹 ∈ V ∧ 𝑃 ∈ V))
12512, 16bitrd 267 . . . . . . . . . . 11 ((𝐺 ∈ UPGraph ∧ 𝐹 ∈ V ∧ 𝑃 ∈ V) → (𝐹(SPathS‘𝐺)𝑃 ↔ ((𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼𝑃:(0...(#‘𝐹))⟶𝑉 ∧ ∀𝑖 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹𝑖)) = {(𝑃𝑖), (𝑃‘(𝑖 + 1))}) ∧ Fun 𝑃)))
126124, 125syl 17 . . . . . . . . . 10 ((((((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) ∧ 𝑃:(0...2)–1-1𝑉) ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))) ∧ 𝐺 ∈ USGraph ) → (𝐹(SPathS‘𝐺)𝑃 ↔ ((𝐹:(0..^(#‘𝐹))–1-1→dom 𝐼𝑃:(0...(#‘𝐹))⟶𝑉 ∧ ∀𝑖 ∈ (0..^(#‘𝐹))(𝐼‘(𝐹𝑖)) = {(𝑃𝑖), (𝑃‘(𝑖 + 1))}) ∧ Fun 𝑃)))
127112, 126mpbird 246 . . . . . . . . 9 ((((((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) ∧ 𝑃:(0...2)–1-1𝑉) ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))) ∧ 𝐺 ∈ USGraph ) → 𝐹(SPathS‘𝐺)𝑃)
128 simpr 476 . . . . . . . . . 10 ((((((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) ∧ 𝑃:(0...2)–1-1𝑉) ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))) ∧ 𝐺 ∈ USGraph ) → 𝐺 ∈ USGraph )
129 simp-4l 802 . . . . . . . . . 10 ((((((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) ∧ 𝑃:(0...2)–1-1𝑉) ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))) ∧ 𝐺 ∈ USGraph ) → (#‘𝐹) = 2)
130128, 129, 1syl2anc 691 . . . . . . . . 9 ((((((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) ∧ 𝑃:(0...2)–1-1𝑉) ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))) ∧ 𝐺 ∈ USGraph ) → (𝐹(PathS‘𝐺)𝑃𝐹(SPathS‘𝐺)𝑃))
131127, 130mpbird 246 . . . . . . . 8 ((((((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) ∧ 𝑃:(0...2)–1-1𝑉) ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))) ∧ 𝐺 ∈ USGraph ) → 𝐹(PathS‘𝐺)𝑃)
132131, 129jca 553 . . . . . . 7 ((((((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) ∧ 𝑃:(0...2)–1-1𝑉) ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))) ∧ 𝐺 ∈ USGraph ) → (𝐹(PathS‘𝐺)𝑃 ∧ (#‘𝐹) = 2))
133132ex 449 . . . . . 6 (((((#‘𝐹) = 2 ∧ 𝐹:(0..^2)–1-1→dom 𝐼) ∧ 𝑃:(0...2)–1-1𝑉) ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))) → (𝐺 ∈ USGraph → (𝐹(PathS‘𝐺)𝑃 ∧ (#‘𝐹) = 2)))
134133exp41 636 . . . . 5 ((#‘𝐹) = 2 → (𝐹:(0..^2)–1-1→dom 𝐼 → (𝑃:(0...2)–1-1𝑉 → (∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧})) → (𝐺 ∈ USGraph → (𝐹(PathS‘𝐺)𝑃 ∧ (#‘𝐹) = 2))))))
13554, 134mpcom 37 . . . 4 (𝐹:(0..^2)–1-1→dom 𝐼 → (𝑃:(0...2)–1-1𝑉 → (∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧})) → (𝐺 ∈ USGraph → (𝐹(PathS‘𝐺)𝑃 ∧ (#‘𝐹) = 2)))))
1361353imp 1249 . . 3 ((𝐹:(0..^2)–1-1→dom 𝐼𝑃:(0...2)–1-1𝑉 ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))) → (𝐺 ∈ USGraph → (𝐹(PathS‘𝐺)𝑃 ∧ (#‘𝐹) = 2)))
137136com12 32 . 2 (𝐺 ∈ USGraph → ((𝐹:(0..^2)–1-1→dom 𝐼𝑃:(0...2)–1-1𝑉 ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧}))) → (𝐹(PathS‘𝐺)𝑃 ∧ (#‘𝐹) = 2)))
13850, 137impbid 201 1 (𝐺 ∈ USGraph → ((𝐹(PathS‘𝐺)𝑃 ∧ (#‘𝐹) = 2) ↔ (𝐹:(0..^2)–1-1→dom 𝐼𝑃:(0...2)–1-1𝑉 ∧ ∃𝑥𝑉𝑦 ∈ (𝑉 ∖ {𝑥})∃𝑧 ∈ (𝑉 ∖ {𝑥, 𝑦})(((𝑃‘0) = 𝑥 ∧ (𝑃‘1) = 𝑦 ∧ (𝑃‘2) = 𝑧) ∧ ((𝐼‘(𝐹‘0)) = {𝑥, 𝑦} ∧ (𝐼‘(𝐹‘1)) = {𝑦, 𝑧})))))
 Colors of variables: wff setvar class Syntax hints:   → wi 4   ↔ wb 195   ∧ wa 383   ∧ w3a 1031   = wceq 1475   ∈ wcel 1977  ∀wral 2896  ∃wrex 2897  Vcvv 3173   ∖ cdif 3537  {csn 4125  {cpr 4127   class class class wbr 4583  ◡ccnv 5037  dom cdm 5038  Fun wfun 5798  ⟶wf 5800  –1-1→wf1 5801  ‘cfv 5804  (class class class)co 6549  0cc0 9815  1c1 9816   + caddc 9818  2c2 10947  ℕ0cn0 11169  ...cfz 12197  ..^cfzo 12334  #chash 12979  Vtxcvtx 25673  iEdgciedg 25674   UPGraph cupgr 25747   USGraph cusgr 40379  1Walksc1wlks 40796  TrailSctrls 40899  PathScpths 40919  SPathScspths 40920 This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1713  ax-4 1728  ax-5 1827  ax-6 1875  ax-7 1922  ax-8 1979  ax-9 1986  ax-10 2006  ax-11 2021  ax-12 2034  ax-13 2234  ax-ext 2590  ax-rep 4699  ax-sep 4709  ax-nul 4717  ax-pow 4769  ax-pr 4833  ax-un 6847  ax-cnex 9871  ax-resscn 9872  ax-1cn 9873  ax-icn 9874  ax-addcl 9875  ax-addrcl 9876  ax-mulcl 9877  ax-mulrcl 9878  ax-mulcom 9879  ax-addass 9880  ax-mulass 9881  ax-distr 9882  ax-i2m1 9883  ax-1ne0 9884  ax-1rid 9885  ax-rnegex 9886  ax-rrecex 9887  ax-cnre 9888  ax-pre-lttri 9889  ax-pre-lttrn 9890  ax-pre-ltadd 9891  ax-pre-mulgt0 9892 This theorem depends on definitions:  df-bi 196  df-or 384  df-an 385  df-ifp 1007  df-3or 1032  df-3an 1033  df-tru 1478  df-ex 1696  df-nf 1701  df-sb 1868  df-eu 2462  df-mo 2463  df-clab 2597  df-cleq 2603  df-clel 2606  df-nfc 2740  df-ne 2782  df-nel 2783  df-ral 2901  df-rex 2902  df-reu 2903  df-rmo 2904  df-rab 2905  df-v 3175  df-sbc 3403  df-csb 3500  df-dif 3543  df-un 3545  df-in 3547  df-ss 3554  df-pss 3556  df-nul 3875  df-if 4037  df-pw 4110  df-sn 4126  df-pr 4128  df-tp 4130  df-op 4132  df-uni 4373  df-int 4411  df-iun 4457  df-br 4584  df-opab 4644  df-mpt 4645  df-tr 4681  df-eprel 4949  df-id 4953  df-po 4959  df-so 4960  df-fr 4997  df-we 4999  df-xp 5044  df-rel 5045  df-cnv 5046  df-co 5047  df-dm 5048  df-rn 5049  df-res 5050  df-ima 5051  df-pred 5597  df-ord 5643  df-on 5644  df-lim 5645  df-suc 5646  df-iota 5768  df-fun 5806  df-fn 5807  df-f 5808  df-f1 5809  df-fo 5810  df-f1o 5811  df-fv 5812  df-riota 6511  df-ov 6552  df-oprab 6553  df-mpt2 6554  df-om 6958  df-1st 7059  df-2nd 7060  df-wrecs 7294  df-recs 7355  df-rdg 7393  df-1o 7447  df-2o 7448  df-oadd 7451  df-er 7629  df-map 7746  df-pm 7747  df-en 7842  df-dom 7843  df-sdom 7844  df-fin 7845  df-card 8648  df-cda 8873  df-pnf 9955  df-mnf 9956  df-xr 9957  df-ltxr 9958  df-le 9959  df-sub 10147  df-neg 10148  df-nn 10898  df-2 10956  df-3 10957  df-n0 11170  df-z 11255  df-uz 11564  df-fz 12198  df-fzo 12335  df-hash 12980  df-word 13154  df-concat 13156  df-s1 13157  df-s2 13444  df-s3 13445  df-uhgr 25724  df-upgr 25749  df-umgr 25750  df-edga 25793  df-uspgr 40380  df-usgr 40381  df-1wlks 40800  df-wlks 40801  df-wlkson 40802  df-trls 40901  df-trlson 40902  df-pths 40923  df-spths 40924  df-pthson 40925  df-spthson 40926 This theorem is referenced by:  usgr2pth0  40971
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