Metamath Proof Explorer


Theorem 2uasbanhVD

Description: The following User's Proof is a Virtual Deduction proof (see wvd1 ) completed automatically by a Metamath tools program invoking mmj2 and the Metamath Proof Assistant. 2uasbanh is 2uasbanhVD without virtual deductions and was automatically derived from 2uasbanhVD . (Contributed by Alan Sare, 31-May-2014) (Proof modification is discouraged.) (New usage is discouraged.)

h1:: |- ( ch <-> ( E. x E. y ( ( x = u /\ y = v ) /\ ph ) /\ E. x E. y ( ( x = u /\ y = v ) /\ ps ) ) )
100:1: |- ( ch -> ( E. x E. y ( ( x = u /\ y = v ) /\ ph ) /\ E. x E. y ( ( x = u /\ y = v ) /\ ps ) ) )
2:100: |- (. ch ->. ( E. x E. y ( ( x = u /\ y = v ) /\ ph ) /\ E. x E. y ( ( x = u /\ y = v ) /\ ps ) ) ).
3:2: |- (. ch ->. E. x E. y ( ( x = u /\ y = v ) /\ ph ) ).
4:3: |- (. ch ->. E. x E. y ( x = u /\ y = v ) ).
5:4: |- (. ch ->. ( -. A. x x = y \/ u = v ) ).
6:5: |- (. ch ->. ( [ u / x ] [ v / y ] ph <-> E. x E. y ( ( x = u /\ y = v ) /\ ph ) ) ).
7:3,6: |- (. ch ->. [ u / x ] [ v / y ] ph ).
8:2: |- (. ch ->. E. x E. y ( ( x = u /\ y = v ) /\ ps ) ).
9:5: |- (. ch ->. ( [ u / x ] [ v / y ] ps <-> E. x E. y ( ( x = u /\ y = v ) /\ ps ) ) ).
10:8,9: |- (. ch ->. [ u / x ] [ v / y ] ps ).
101:: |- ( [ v / y ] ( ph /\ ps ) <-> ( [ v / y ] ph /\ [ v / y ] ps ) )
102:101: |- ( [ u / x ] [ v / y ] ( ph /\ ps ) <-> [ u / x ] ( [ v / y ] ph /\ [ v / y ] ps ) )
103:: |- ( [ u / x ] ( [ v / y ] ph /\ [ v / y ] ps ) <-> ( [ u / x ] [ v / y ] ph /\ [ u / x ] [ v / y ] ps ) )
104:102,103: |- ( [ u / x ] [ v / y ] ( ph /\ ps ) <-> ( [ u / x ] [ v / y ] ph /\ [ u / x ] [ v / y ] ps ) )
11:7,10,104: |- (. ch ->. [ u / x ] [ v / y ] ( ph /\ ps ) ).
110:5: |- (. ch ->. ( [ u / x ] [ v / y ] ( ph /\ ps ) <-> E. x E. y ( ( x = u /\ y = v ) /\ ( ph /\ ps ) ) ) ).
12:11,110: |- (. ch ->. E. x E. y ( ( x = u /\ y = v ) /\ ( ph /\ ps ) ) ).
120:12: |- ( ch -> E. x E. y ( ( x = u /\ y = v ) /\ ( ph /\ ps ) ) )
13:1,120: |- ( ( E. x E. y ( ( x = u /\ y = v ) /\ ph ) /\ E. x E. y ( ( x = u /\ y = v ) /\ ps ) ) -> E. x E. y ( ( x = u /\ y = v ) /\ ( ph /\ ps ) ) )
14:: |- (. ( ( x = u /\ y = v ) /\ ( ph /\ ps ) ) ->. ( ( x = u /\ y = v ) /\ ( ph /\ ps ) ) ).
15:14: |- (. ( ( x = u /\ y = v ) /\ ( ph /\ ps ) ) ->. ( x = u /\ y = v ) ).
16:14: |- (. ( ( x = u /\ y = v ) /\ ( ph /\ ps ) ) ->. ( ph /\ ps ) ).
17:16: |- (. ( ( x = u /\ y = v ) /\ ( ph /\ ps ) ) ->. ph ).
18:15,17: |- (. ( ( x = u /\ y = v ) /\ ( ph /\ ps ) ) ->. ( ( x = u /\ y = v ) /\ ph ) ).
19:18: |- ( ( ( x = u /\ y = v ) /\ ( ph /\ ps ) ) -> ( ( x = u /\ y = v ) /\ ph ) )
20:19: |- ( E. y ( ( x = u /\ y = v ) /\ ( ph /\ ps ) ) -> E. y ( ( x = u /\ y = v ) /\ ph ) )
21:20: |- ( E. x E. y ( ( x = u /\ y = v ) /\ ( ph /\ ps ) ) -> E. x E. y ( ( x = u /\ y = v ) /\ ph ) )
22:16: |- (. ( ( x = u /\ y = v ) /\ ( ph /\ ps ) ) ->. ps ).
23:15,22: |- (. ( ( x = u /\ y = v ) /\ ( ph /\ ps ) ) ->. ( ( x = u /\ y = v ) /\ ps ) ).
24:23: |- ( ( ( x = u /\ y = v ) /\ ( ph /\ ps ) ) -> ( ( x = u /\ y = v ) /\ ps ) )
25:24: |- ( E. y ( ( x = u /\ y = v ) /\ ( ph /\ ps ) ) -> E. y ( ( x = u /\ y = v ) /\ ps ) )
26:25: |- ( E. x E. y ( ( x = u /\ y = v ) /\ ( ph /\ ps ) ) -> E. x E. y ( ( x = u /\ y = v ) /\ ps ) )
27:21,26: |- ( E. x E. y ( ( x = u /\ y = v ) /\ ( ph /\ ps ) ) -> ( E. x E. y ( ( x = u /\ y = v ) /\ ph ) /\ E. x E. y ( ( x = u /\ y = v ) /\ ps ) ) )
qed:13,27: |- ( E. x E. y ( ( x = u /\ y = v ) /\ ( ph /\ ps ) ) <-> ( E. x E. y ( ( x = u /\ y = v ) /\ ph ) /\ E. x E. y ( ( x = u /\ y = v ) /\ ps ) ) )

Ref Expression
Hypothesis 2uasbanhVD.1 ( 𝜒 ↔ ( ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜑 ) ∧ ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜓 ) ) )
Assertion 2uasbanhVD ( ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) ) ↔ ( ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜑 ) ∧ ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜓 ) ) )

Proof

Step Hyp Ref Expression
1 2uasbanhVD.1 ( 𝜒 ↔ ( ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜑 ) ∧ ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜓 ) ) )
2 idn1 (    ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) )    ▶    ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) )    )
3 simpl ( ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) ) → ( 𝑥 = 𝑢𝑦 = 𝑣 ) )
4 2 3 e1a (    ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) )    ▶    ( 𝑥 = 𝑢𝑦 = 𝑣 )    )
5 simpr ( ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) ) → ( 𝜑𝜓 ) )
6 2 5 e1a (    ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) )    ▶    ( 𝜑𝜓 )    )
7 simpl ( ( 𝜑𝜓 ) → 𝜑 )
8 6 7 e1a (    ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) )    ▶    𝜑    )
9 pm3.2 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) → ( 𝜑 → ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜑 ) ) )
10 4 8 9 e11 (    ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) )    ▶    ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜑 )    )
11 10 in1 ( ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) ) → ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜑 ) )
12 11 eximi ( ∃ 𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) ) → ∃ 𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜑 ) )
13 12 eximi ( ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) ) → ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜑 ) )
14 simpr ( ( 𝜑𝜓 ) → 𝜓 )
15 6 14 e1a (    ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) )    ▶    𝜓    )
16 pm3.2 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) → ( 𝜓 → ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜓 ) ) )
17 4 15 16 e11 (    ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) )    ▶    ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜓 )    )
18 17 in1 ( ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) ) → ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜓 ) )
19 18 eximi ( ∃ 𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) ) → ∃ 𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜓 ) )
20 19 eximi ( ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) ) → ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜓 ) )
21 13 20 jca ( ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) ) → ( ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜑 ) ∧ ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜓 ) ) )
22 1 biimpi ( 𝜒 → ( ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜑 ) ∧ ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜓 ) ) )
23 22 dfvd1ir (    𝜒    ▶    ( ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜑 ) ∧ ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜓 ) )    )
24 simpl ( ( ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜑 ) ∧ ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜓 ) ) → ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜑 ) )
25 23 24 e1a (    𝜒    ▶   𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜑 )    )
26 simpl ( ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜑 ) → ( 𝑥 = 𝑢𝑦 = 𝑣 ) )
27 26 2eximi ( ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜑 ) → ∃ 𝑥𝑦 ( 𝑥 = 𝑢𝑦 = 𝑣 ) )
28 25 27 e1a (    𝜒    ▶   𝑥𝑦 ( 𝑥 = 𝑢𝑦 = 𝑣 )    )
29 ax6e2ndeq ( ( ¬ ∀ 𝑥 𝑥 = 𝑦𝑢 = 𝑣 ) ↔ ∃ 𝑥𝑦 ( 𝑥 = 𝑢𝑦 = 𝑣 ) )
30 29 biimpri ( ∃ 𝑥𝑦 ( 𝑥 = 𝑢𝑦 = 𝑣 ) → ( ¬ ∀ 𝑥 𝑥 = 𝑦𝑢 = 𝑣 ) )
31 28 30 e1a (    𝜒    ▶    ( ¬ ∀ 𝑥 𝑥 = 𝑦𝑢 = 𝑣 )    )
32 2sb5nd ( ( ¬ ∀ 𝑥 𝑥 = 𝑦𝑢 = 𝑣 ) → ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜑 ↔ ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜑 ) ) )
33 31 32 e1a (    𝜒    ▶    ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜑 ↔ ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜑 ) )    )
34 biimpr ( ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜑 ↔ ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜑 ) ) → ( ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜑 ) → [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜑 ) )
35 34 com12 ( ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜑 ) → ( ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜑 ↔ ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜑 ) ) → [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜑 ) )
36 25 33 35 e11 (    𝜒    ▶    [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜑    )
37 simpr ( ( ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜑 ) ∧ ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜓 ) ) → ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜓 ) )
38 23 37 e1a (    𝜒    ▶   𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜓 )    )
39 2sb5nd ( ( ¬ ∀ 𝑥 𝑥 = 𝑦𝑢 = 𝑣 ) → ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜓 ↔ ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜓 ) ) )
40 31 39 e1a (    𝜒    ▶    ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜓 ↔ ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜓 ) )    )
41 biimpr ( ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜓 ↔ ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜓 ) ) → ( ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜓 ) → [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜓 ) )
42 41 com12 ( ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜓 ) → ( ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜓 ↔ ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜓 ) ) → [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜓 ) )
43 38 40 42 e11 (    𝜒    ▶    [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜓    )
44 sban ( [ 𝑣 / 𝑦 ] ( 𝜑𝜓 ) ↔ ( [ 𝑣 / 𝑦 ] 𝜑 ∧ [ 𝑣 / 𝑦 ] 𝜓 ) )
45 44 sbbii ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] ( 𝜑𝜓 ) ↔ [ 𝑢 / 𝑥 ] ( [ 𝑣 / 𝑦 ] 𝜑 ∧ [ 𝑣 / 𝑦 ] 𝜓 ) )
46 sban ( [ 𝑢 / 𝑥 ] ( [ 𝑣 / 𝑦 ] 𝜑 ∧ [ 𝑣 / 𝑦 ] 𝜓 ) ↔ ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜑 ∧ [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜓 ) )
47 45 46 bitri ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] ( 𝜑𝜓 ) ↔ ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜑 ∧ [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜓 ) )
48 simplbi2comt ( ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] ( 𝜑𝜓 ) ↔ ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜑 ∧ [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜓 ) ) → ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜓 → ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜑 → [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] ( 𝜑𝜓 ) ) ) )
49 48 com13 ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜑 → ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜓 → ( ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] ( 𝜑𝜓 ) ↔ ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜑 ∧ [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] 𝜓 ) ) → [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] ( 𝜑𝜓 ) ) ) )
50 36 43 47 49 e110 (    𝜒    ▶    [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] ( 𝜑𝜓 )    )
51 2sb5nd ( ( ¬ ∀ 𝑥 𝑥 = 𝑦𝑢 = 𝑣 ) → ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] ( 𝜑𝜓 ) ↔ ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) ) ) )
52 31 51 e1a (    𝜒    ▶    ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] ( 𝜑𝜓 ) ↔ ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) ) )    )
53 biimp ( ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] ( 𝜑𝜓 ) ↔ ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) ) ) → ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] ( 𝜑𝜓 ) → ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) ) ) )
54 53 com12 ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] ( 𝜑𝜓 ) → ( ( [ 𝑢 / 𝑥 ] [ 𝑣 / 𝑦 ] ( 𝜑𝜓 ) ↔ ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) ) ) → ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) ) ) )
55 50 52 54 e11 (    𝜒    ▶   𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) )    )
56 55 in1 ( 𝜒 → ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) ) )
57 1 56 sylbir ( ( ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜑 ) ∧ ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜓 ) ) → ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) ) )
58 21 57 impbii ( ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ ( 𝜑𝜓 ) ) ↔ ( ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜑 ) ∧ ∃ 𝑥𝑦 ( ( 𝑥 = 𝑢𝑦 = 𝑣 ) ∧ 𝜓 ) ) )