Metamath Proof Explorer


Theorem istrkgb

Description: Property of being a Tarski geometry - betweenness part. (Contributed by Thierry Arnoux, 14-Mar-2019)

Ref Expression
Hypotheses istrkg.p 𝑃 = ( Base ‘ 𝐺 )
istrkg.d = ( dist ‘ 𝐺 )
istrkg.i 𝐼 = ( Itv ‘ 𝐺 )
Assertion istrkgb ( 𝐺 ∈ TarskiGB ↔ ( 𝐺 ∈ V ∧ ( ∀ 𝑥𝑃𝑦𝑃 ( 𝑦 ∈ ( 𝑥 𝐼 𝑥 ) → 𝑥 = 𝑦 ) ∧ ∀ 𝑥𝑃𝑦𝑃𝑧𝑃𝑢𝑃𝑣𝑃 ( ( 𝑢 ∈ ( 𝑥 𝐼 𝑧 ) ∧ 𝑣 ∈ ( 𝑦 𝐼 𝑧 ) ) → ∃ 𝑎𝑃 ( 𝑎 ∈ ( 𝑢 𝐼 𝑦 ) ∧ 𝑎 ∈ ( 𝑣 𝐼 𝑥 ) ) ) ∧ ∀ 𝑠 ∈ 𝒫 𝑃𝑡 ∈ 𝒫 𝑃 ( ∃ 𝑎𝑃𝑥𝑠𝑦𝑡 𝑥 ∈ ( 𝑎 𝐼 𝑦 ) → ∃ 𝑏𝑃𝑥𝑠𝑦𝑡 𝑏 ∈ ( 𝑥 𝐼 𝑦 ) ) ) ) )

Proof

Step Hyp Ref Expression
1 istrkg.p 𝑃 = ( Base ‘ 𝐺 )
2 istrkg.d = ( dist ‘ 𝐺 )
3 istrkg.i 𝐼 = ( Itv ‘ 𝐺 )
4 simpl ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → 𝑝 = 𝑃 )
5 simpr ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → 𝑖 = 𝐼 )
6 5 oveqd ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( 𝑥 𝑖 𝑥 ) = ( 𝑥 𝐼 𝑥 ) )
7 6 eleq2d ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( 𝑦 ∈ ( 𝑥 𝑖 𝑥 ) ↔ 𝑦 ∈ ( 𝑥 𝐼 𝑥 ) ) )
8 7 imbi1d ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( ( 𝑦 ∈ ( 𝑥 𝑖 𝑥 ) → 𝑥 = 𝑦 ) ↔ ( 𝑦 ∈ ( 𝑥 𝐼 𝑥 ) → 𝑥 = 𝑦 ) ) )
9 4 8 raleqbidv ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( ∀ 𝑦𝑝 ( 𝑦 ∈ ( 𝑥 𝑖 𝑥 ) → 𝑥 = 𝑦 ) ↔ ∀ 𝑦𝑃 ( 𝑦 ∈ ( 𝑥 𝐼 𝑥 ) → 𝑥 = 𝑦 ) ) )
10 4 9 raleqbidv ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( ∀ 𝑥𝑝𝑦𝑝 ( 𝑦 ∈ ( 𝑥 𝑖 𝑥 ) → 𝑥 = 𝑦 ) ↔ ∀ 𝑥𝑃𝑦𝑃 ( 𝑦 ∈ ( 𝑥 𝐼 𝑥 ) → 𝑥 = 𝑦 ) ) )
11 5 oveqd ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( 𝑥 𝑖 𝑧 ) = ( 𝑥 𝐼 𝑧 ) )
12 11 eleq2d ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( 𝑢 ∈ ( 𝑥 𝑖 𝑧 ) ↔ 𝑢 ∈ ( 𝑥 𝐼 𝑧 ) ) )
13 5 oveqd ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( 𝑦 𝑖 𝑧 ) = ( 𝑦 𝐼 𝑧 ) )
14 13 eleq2d ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( 𝑣 ∈ ( 𝑦 𝑖 𝑧 ) ↔ 𝑣 ∈ ( 𝑦 𝐼 𝑧 ) ) )
15 12 14 anbi12d ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( ( 𝑢 ∈ ( 𝑥 𝑖 𝑧 ) ∧ 𝑣 ∈ ( 𝑦 𝑖 𝑧 ) ) ↔ ( 𝑢 ∈ ( 𝑥 𝐼 𝑧 ) ∧ 𝑣 ∈ ( 𝑦 𝐼 𝑧 ) ) ) )
16 5 oveqd ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( 𝑢 𝑖 𝑦 ) = ( 𝑢 𝐼 𝑦 ) )
17 16 eleq2d ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( 𝑎 ∈ ( 𝑢 𝑖 𝑦 ) ↔ 𝑎 ∈ ( 𝑢 𝐼 𝑦 ) ) )
18 5 oveqd ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( 𝑣 𝑖 𝑥 ) = ( 𝑣 𝐼 𝑥 ) )
19 18 eleq2d ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( 𝑎 ∈ ( 𝑣 𝑖 𝑥 ) ↔ 𝑎 ∈ ( 𝑣 𝐼 𝑥 ) ) )
20 17 19 anbi12d ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( ( 𝑎 ∈ ( 𝑢 𝑖 𝑦 ) ∧ 𝑎 ∈ ( 𝑣 𝑖 𝑥 ) ) ↔ ( 𝑎 ∈ ( 𝑢 𝐼 𝑦 ) ∧ 𝑎 ∈ ( 𝑣 𝐼 𝑥 ) ) ) )
21 4 20 rexeqbidv ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( ∃ 𝑎𝑝 ( 𝑎 ∈ ( 𝑢 𝑖 𝑦 ) ∧ 𝑎 ∈ ( 𝑣 𝑖 𝑥 ) ) ↔ ∃ 𝑎𝑃 ( 𝑎 ∈ ( 𝑢 𝐼 𝑦 ) ∧ 𝑎 ∈ ( 𝑣 𝐼 𝑥 ) ) ) )
22 15 21 imbi12d ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( ( ( 𝑢 ∈ ( 𝑥 𝑖 𝑧 ) ∧ 𝑣 ∈ ( 𝑦 𝑖 𝑧 ) ) → ∃ 𝑎𝑝 ( 𝑎 ∈ ( 𝑢 𝑖 𝑦 ) ∧ 𝑎 ∈ ( 𝑣 𝑖 𝑥 ) ) ) ↔ ( ( 𝑢 ∈ ( 𝑥 𝐼 𝑧 ) ∧ 𝑣 ∈ ( 𝑦 𝐼 𝑧 ) ) → ∃ 𝑎𝑃 ( 𝑎 ∈ ( 𝑢 𝐼 𝑦 ) ∧ 𝑎 ∈ ( 𝑣 𝐼 𝑥 ) ) ) ) )
23 4 22 raleqbidv ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( ∀ 𝑣𝑝 ( ( 𝑢 ∈ ( 𝑥 𝑖 𝑧 ) ∧ 𝑣 ∈ ( 𝑦 𝑖 𝑧 ) ) → ∃ 𝑎𝑝 ( 𝑎 ∈ ( 𝑢 𝑖 𝑦 ) ∧ 𝑎 ∈ ( 𝑣 𝑖 𝑥 ) ) ) ↔ ∀ 𝑣𝑃 ( ( 𝑢 ∈ ( 𝑥 𝐼 𝑧 ) ∧ 𝑣 ∈ ( 𝑦 𝐼 𝑧 ) ) → ∃ 𝑎𝑃 ( 𝑎 ∈ ( 𝑢 𝐼 𝑦 ) ∧ 𝑎 ∈ ( 𝑣 𝐼 𝑥 ) ) ) ) )
24 4 23 raleqbidv ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( ∀ 𝑢𝑝𝑣𝑝 ( ( 𝑢 ∈ ( 𝑥 𝑖 𝑧 ) ∧ 𝑣 ∈ ( 𝑦 𝑖 𝑧 ) ) → ∃ 𝑎𝑝 ( 𝑎 ∈ ( 𝑢 𝑖 𝑦 ) ∧ 𝑎 ∈ ( 𝑣 𝑖 𝑥 ) ) ) ↔ ∀ 𝑢𝑃𝑣𝑃 ( ( 𝑢 ∈ ( 𝑥 𝐼 𝑧 ) ∧ 𝑣 ∈ ( 𝑦 𝐼 𝑧 ) ) → ∃ 𝑎𝑃 ( 𝑎 ∈ ( 𝑢 𝐼 𝑦 ) ∧ 𝑎 ∈ ( 𝑣 𝐼 𝑥 ) ) ) ) )
25 4 24 raleqbidv ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( ∀ 𝑧𝑝𝑢𝑝𝑣𝑝 ( ( 𝑢 ∈ ( 𝑥 𝑖 𝑧 ) ∧ 𝑣 ∈ ( 𝑦 𝑖 𝑧 ) ) → ∃ 𝑎𝑝 ( 𝑎 ∈ ( 𝑢 𝑖 𝑦 ) ∧ 𝑎 ∈ ( 𝑣 𝑖 𝑥 ) ) ) ↔ ∀ 𝑧𝑃𝑢𝑃𝑣𝑃 ( ( 𝑢 ∈ ( 𝑥 𝐼 𝑧 ) ∧ 𝑣 ∈ ( 𝑦 𝐼 𝑧 ) ) → ∃ 𝑎𝑃 ( 𝑎 ∈ ( 𝑢 𝐼 𝑦 ) ∧ 𝑎 ∈ ( 𝑣 𝐼 𝑥 ) ) ) ) )
26 4 25 raleqbidv ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( ∀ 𝑦𝑝𝑧𝑝𝑢𝑝𝑣𝑝 ( ( 𝑢 ∈ ( 𝑥 𝑖 𝑧 ) ∧ 𝑣 ∈ ( 𝑦 𝑖 𝑧 ) ) → ∃ 𝑎𝑝 ( 𝑎 ∈ ( 𝑢 𝑖 𝑦 ) ∧ 𝑎 ∈ ( 𝑣 𝑖 𝑥 ) ) ) ↔ ∀ 𝑦𝑃𝑧𝑃𝑢𝑃𝑣𝑃 ( ( 𝑢 ∈ ( 𝑥 𝐼 𝑧 ) ∧ 𝑣 ∈ ( 𝑦 𝐼 𝑧 ) ) → ∃ 𝑎𝑃 ( 𝑎 ∈ ( 𝑢 𝐼 𝑦 ) ∧ 𝑎 ∈ ( 𝑣 𝐼 𝑥 ) ) ) ) )
27 4 26 raleqbidv ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( ∀ 𝑥𝑝𝑦𝑝𝑧𝑝𝑢𝑝𝑣𝑝 ( ( 𝑢 ∈ ( 𝑥 𝑖 𝑧 ) ∧ 𝑣 ∈ ( 𝑦 𝑖 𝑧 ) ) → ∃ 𝑎𝑝 ( 𝑎 ∈ ( 𝑢 𝑖 𝑦 ) ∧ 𝑎 ∈ ( 𝑣 𝑖 𝑥 ) ) ) ↔ ∀ 𝑥𝑃𝑦𝑃𝑧𝑃𝑢𝑃𝑣𝑃 ( ( 𝑢 ∈ ( 𝑥 𝐼 𝑧 ) ∧ 𝑣 ∈ ( 𝑦 𝐼 𝑧 ) ) → ∃ 𝑎𝑃 ( 𝑎 ∈ ( 𝑢 𝐼 𝑦 ) ∧ 𝑎 ∈ ( 𝑣 𝐼 𝑥 ) ) ) ) )
28 4 pweqd ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → 𝒫 𝑝 = 𝒫 𝑃 )
29 5 oveqd ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( 𝑎 𝑖 𝑦 ) = ( 𝑎 𝐼 𝑦 ) )
30 29 eleq2d ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( 𝑥 ∈ ( 𝑎 𝑖 𝑦 ) ↔ 𝑥 ∈ ( 𝑎 𝐼 𝑦 ) ) )
31 30 2ralbidv ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( ∀ 𝑥𝑠𝑦𝑡 𝑥 ∈ ( 𝑎 𝑖 𝑦 ) ↔ ∀ 𝑥𝑠𝑦𝑡 𝑥 ∈ ( 𝑎 𝐼 𝑦 ) ) )
32 4 31 rexeqbidv ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( ∃ 𝑎𝑝𝑥𝑠𝑦𝑡 𝑥 ∈ ( 𝑎 𝑖 𝑦 ) ↔ ∃ 𝑎𝑃𝑥𝑠𝑦𝑡 𝑥 ∈ ( 𝑎 𝐼 𝑦 ) ) )
33 5 oveqd ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( 𝑥 𝑖 𝑦 ) = ( 𝑥 𝐼 𝑦 ) )
34 33 eleq2d ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( 𝑏 ∈ ( 𝑥 𝑖 𝑦 ) ↔ 𝑏 ∈ ( 𝑥 𝐼 𝑦 ) ) )
35 34 2ralbidv ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( ∀ 𝑥𝑠𝑦𝑡 𝑏 ∈ ( 𝑥 𝑖 𝑦 ) ↔ ∀ 𝑥𝑠𝑦𝑡 𝑏 ∈ ( 𝑥 𝐼 𝑦 ) ) )
36 4 35 rexeqbidv ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( ∃ 𝑏𝑝𝑥𝑠𝑦𝑡 𝑏 ∈ ( 𝑥 𝑖 𝑦 ) ↔ ∃ 𝑏𝑃𝑥𝑠𝑦𝑡 𝑏 ∈ ( 𝑥 𝐼 𝑦 ) ) )
37 32 36 imbi12d ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( ( ∃ 𝑎𝑝𝑥𝑠𝑦𝑡 𝑥 ∈ ( 𝑎 𝑖 𝑦 ) → ∃ 𝑏𝑝𝑥𝑠𝑦𝑡 𝑏 ∈ ( 𝑥 𝑖 𝑦 ) ) ↔ ( ∃ 𝑎𝑃𝑥𝑠𝑦𝑡 𝑥 ∈ ( 𝑎 𝐼 𝑦 ) → ∃ 𝑏𝑃𝑥𝑠𝑦𝑡 𝑏 ∈ ( 𝑥 𝐼 𝑦 ) ) ) )
38 28 37 raleqbidv ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( ∀ 𝑡 ∈ 𝒫 𝑝 ( ∃ 𝑎𝑝𝑥𝑠𝑦𝑡 𝑥 ∈ ( 𝑎 𝑖 𝑦 ) → ∃ 𝑏𝑝𝑥𝑠𝑦𝑡 𝑏 ∈ ( 𝑥 𝑖 𝑦 ) ) ↔ ∀ 𝑡 ∈ 𝒫 𝑃 ( ∃ 𝑎𝑃𝑥𝑠𝑦𝑡 𝑥 ∈ ( 𝑎 𝐼 𝑦 ) → ∃ 𝑏𝑃𝑥𝑠𝑦𝑡 𝑏 ∈ ( 𝑥 𝐼 𝑦 ) ) ) )
39 28 38 raleqbidv ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( ∀ 𝑠 ∈ 𝒫 𝑝𝑡 ∈ 𝒫 𝑝 ( ∃ 𝑎𝑝𝑥𝑠𝑦𝑡 𝑥 ∈ ( 𝑎 𝑖 𝑦 ) → ∃ 𝑏𝑝𝑥𝑠𝑦𝑡 𝑏 ∈ ( 𝑥 𝑖 𝑦 ) ) ↔ ∀ 𝑠 ∈ 𝒫 𝑃𝑡 ∈ 𝒫 𝑃 ( ∃ 𝑎𝑃𝑥𝑠𝑦𝑡 𝑥 ∈ ( 𝑎 𝐼 𝑦 ) → ∃ 𝑏𝑃𝑥𝑠𝑦𝑡 𝑏 ∈ ( 𝑥 𝐼 𝑦 ) ) ) )
40 10 27 39 3anbi123d ( ( 𝑝 = 𝑃𝑖 = 𝐼 ) → ( ( ∀ 𝑥𝑝𝑦𝑝 ( 𝑦 ∈ ( 𝑥 𝑖 𝑥 ) → 𝑥 = 𝑦 ) ∧ ∀ 𝑥𝑝𝑦𝑝𝑧𝑝𝑢𝑝𝑣𝑝 ( ( 𝑢 ∈ ( 𝑥 𝑖 𝑧 ) ∧ 𝑣 ∈ ( 𝑦 𝑖 𝑧 ) ) → ∃ 𝑎𝑝 ( 𝑎 ∈ ( 𝑢 𝑖 𝑦 ) ∧ 𝑎 ∈ ( 𝑣 𝑖 𝑥 ) ) ) ∧ ∀ 𝑠 ∈ 𝒫 𝑝𝑡 ∈ 𝒫 𝑝 ( ∃ 𝑎𝑝𝑥𝑠𝑦𝑡 𝑥 ∈ ( 𝑎 𝑖 𝑦 ) → ∃ 𝑏𝑝𝑥𝑠𝑦𝑡 𝑏 ∈ ( 𝑥 𝑖 𝑦 ) ) ) ↔ ( ∀ 𝑥𝑃𝑦𝑃 ( 𝑦 ∈ ( 𝑥 𝐼 𝑥 ) → 𝑥 = 𝑦 ) ∧ ∀ 𝑥𝑃𝑦𝑃𝑧𝑃𝑢𝑃𝑣𝑃 ( ( 𝑢 ∈ ( 𝑥 𝐼 𝑧 ) ∧ 𝑣 ∈ ( 𝑦 𝐼 𝑧 ) ) → ∃ 𝑎𝑃 ( 𝑎 ∈ ( 𝑢 𝐼 𝑦 ) ∧ 𝑎 ∈ ( 𝑣 𝐼 𝑥 ) ) ) ∧ ∀ 𝑠 ∈ 𝒫 𝑃𝑡 ∈ 𝒫 𝑃 ( ∃ 𝑎𝑃𝑥𝑠𝑦𝑡 𝑥 ∈ ( 𝑎 𝐼 𝑦 ) → ∃ 𝑏𝑃𝑥𝑠𝑦𝑡 𝑏 ∈ ( 𝑥 𝐼 𝑦 ) ) ) ) )
41 1 3 40 sbcie2s ( 𝑓 = 𝐺 → ( [ ( Base ‘ 𝑓 ) / 𝑝 ] [ ( Itv ‘ 𝑓 ) / 𝑖 ] ( ∀ 𝑥𝑝𝑦𝑝 ( 𝑦 ∈ ( 𝑥 𝑖 𝑥 ) → 𝑥 = 𝑦 ) ∧ ∀ 𝑥𝑝𝑦𝑝𝑧𝑝𝑢𝑝𝑣𝑝 ( ( 𝑢 ∈ ( 𝑥 𝑖 𝑧 ) ∧ 𝑣 ∈ ( 𝑦 𝑖 𝑧 ) ) → ∃ 𝑎𝑝 ( 𝑎 ∈ ( 𝑢 𝑖 𝑦 ) ∧ 𝑎 ∈ ( 𝑣 𝑖 𝑥 ) ) ) ∧ ∀ 𝑠 ∈ 𝒫 𝑝𝑡 ∈ 𝒫 𝑝 ( ∃ 𝑎𝑝𝑥𝑠𝑦𝑡 𝑥 ∈ ( 𝑎 𝑖 𝑦 ) → ∃ 𝑏𝑝𝑥𝑠𝑦𝑡 𝑏 ∈ ( 𝑥 𝑖 𝑦 ) ) ) ↔ ( ∀ 𝑥𝑃𝑦𝑃 ( 𝑦 ∈ ( 𝑥 𝐼 𝑥 ) → 𝑥 = 𝑦 ) ∧ ∀ 𝑥𝑃𝑦𝑃𝑧𝑃𝑢𝑃𝑣𝑃 ( ( 𝑢 ∈ ( 𝑥 𝐼 𝑧 ) ∧ 𝑣 ∈ ( 𝑦 𝐼 𝑧 ) ) → ∃ 𝑎𝑃 ( 𝑎 ∈ ( 𝑢 𝐼 𝑦 ) ∧ 𝑎 ∈ ( 𝑣 𝐼 𝑥 ) ) ) ∧ ∀ 𝑠 ∈ 𝒫 𝑃𝑡 ∈ 𝒫 𝑃 ( ∃ 𝑎𝑃𝑥𝑠𝑦𝑡 𝑥 ∈ ( 𝑎 𝐼 𝑦 ) → ∃ 𝑏𝑃𝑥𝑠𝑦𝑡 𝑏 ∈ ( 𝑥 𝐼 𝑦 ) ) ) ) )
42 df-trkgb TarskiGB = { 𝑓[ ( Base ‘ 𝑓 ) / 𝑝 ] [ ( Itv ‘ 𝑓 ) / 𝑖 ] ( ∀ 𝑥𝑝𝑦𝑝 ( 𝑦 ∈ ( 𝑥 𝑖 𝑥 ) → 𝑥 = 𝑦 ) ∧ ∀ 𝑥𝑝𝑦𝑝𝑧𝑝𝑢𝑝𝑣𝑝 ( ( 𝑢 ∈ ( 𝑥 𝑖 𝑧 ) ∧ 𝑣 ∈ ( 𝑦 𝑖 𝑧 ) ) → ∃ 𝑎𝑝 ( 𝑎 ∈ ( 𝑢 𝑖 𝑦 ) ∧ 𝑎 ∈ ( 𝑣 𝑖 𝑥 ) ) ) ∧ ∀ 𝑠 ∈ 𝒫 𝑝𝑡 ∈ 𝒫 𝑝 ( ∃ 𝑎𝑝𝑥𝑠𝑦𝑡 𝑥 ∈ ( 𝑎 𝑖 𝑦 ) → ∃ 𝑏𝑝𝑥𝑠𝑦𝑡 𝑏 ∈ ( 𝑥 𝑖 𝑦 ) ) ) }
43 41 42 elab4g ( 𝐺 ∈ TarskiGB ↔ ( 𝐺 ∈ V ∧ ( ∀ 𝑥𝑃𝑦𝑃 ( 𝑦 ∈ ( 𝑥 𝐼 𝑥 ) → 𝑥 = 𝑦 ) ∧ ∀ 𝑥𝑃𝑦𝑃𝑧𝑃𝑢𝑃𝑣𝑃 ( ( 𝑢 ∈ ( 𝑥 𝐼 𝑧 ) ∧ 𝑣 ∈ ( 𝑦 𝐼 𝑧 ) ) → ∃ 𝑎𝑃 ( 𝑎 ∈ ( 𝑢 𝐼 𝑦 ) ∧ 𝑎 ∈ ( 𝑣 𝐼 𝑥 ) ) ) ∧ ∀ 𝑠 ∈ 𝒫 𝑃𝑡 ∈ 𝒫 𝑃 ( ∃ 𝑎𝑃𝑥𝑠𝑦𝑡 𝑥 ∈ ( 𝑎 𝐼 𝑦 ) → ∃ 𝑏𝑃𝑥𝑠𝑦𝑡 𝑏 ∈ ( 𝑥 𝐼 𝑦 ) ) ) ) )