| Step | Hyp | Ref | Expression | 
						
							| 1 |  | unxpwdom3.av | ⊢ ( 𝜑  →  𝐴  ∈  𝑉 ) | 
						
							| 2 |  | unxpwdom3.bv | ⊢ ( 𝜑  →  𝐵  ∈  𝑊 ) | 
						
							| 3 |  | unxpwdom3.dv | ⊢ ( 𝜑  →  𝐷  ∈  𝑋 ) | 
						
							| 4 |  | unxpwdom3.ov | ⊢ ( ( 𝜑  ∧  𝑎  ∈  𝐶  ∧  𝑏  ∈  𝐷 )  →  ( 𝑎  +  𝑏 )  ∈  ( 𝐴  ∪  𝐵 ) ) | 
						
							| 5 |  | unxpwdom3.lc | ⊢ ( ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  ∧  ( 𝑏  ∈  𝐷  ∧  𝑐  ∈  𝐷 ) )  →  ( ( 𝑎  +  𝑏 )  =  ( 𝑎  +  𝑐 )  ↔  𝑏  =  𝑐 ) ) | 
						
							| 6 |  | unxpwdom3.rc | ⊢ ( ( ( 𝜑  ∧  𝑑  ∈  𝐷 )  ∧  ( 𝑎  ∈  𝐶  ∧  𝑐  ∈  𝐶 ) )  →  ( ( 𝑐  +  𝑑 )  =  ( 𝑎  +  𝑑 )  ↔  𝑐  =  𝑎 ) ) | 
						
							| 7 |  | unxpwdom3.ni | ⊢ ( 𝜑  →  ¬  𝐷  ≼  𝐴 ) | 
						
							| 8 | 3 2 | xpexd | ⊢ ( 𝜑  →  ( 𝐷  ×  𝐵 )  ∈  V ) | 
						
							| 9 |  | simprr | ⊢ ( ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  ∧  ( 𝑑  ∈  𝐷  ∧  ( 𝑎  +  𝑑 )  ∈  𝐵 ) )  →  ( 𝑎  +  𝑑 )  ∈  𝐵 ) | 
						
							| 10 |  | simplr | ⊢ ( ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  ∧  ( 𝑑  ∈  𝐷  ∧  ( 𝑎  +  𝑑 )  ∈  𝐵 ) )  →  𝑎  ∈  𝐶 ) | 
						
							| 11 | 6 | an4s | ⊢ ( ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  ∧  ( 𝑑  ∈  𝐷  ∧  𝑐  ∈  𝐶 ) )  →  ( ( 𝑐  +  𝑑 )  =  ( 𝑎  +  𝑑 )  ↔  𝑐  =  𝑎 ) ) | 
						
							| 12 | 11 | anassrs | ⊢ ( ( ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  ∧  𝑑  ∈  𝐷 )  ∧  𝑐  ∈  𝐶 )  →  ( ( 𝑐  +  𝑑 )  =  ( 𝑎  +  𝑑 )  ↔  𝑐  =  𝑎 ) ) | 
						
							| 13 | 12 | adantlrr | ⊢ ( ( ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  ∧  ( 𝑑  ∈  𝐷  ∧  ( 𝑎  +  𝑑 )  ∈  𝐵 ) )  ∧  𝑐  ∈  𝐶 )  →  ( ( 𝑐  +  𝑑 )  =  ( 𝑎  +  𝑑 )  ↔  𝑐  =  𝑎 ) ) | 
						
							| 14 | 10 13 | riota5 | ⊢ ( ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  ∧  ( 𝑑  ∈  𝐷  ∧  ( 𝑎  +  𝑑 )  ∈  𝐵 ) )  →  ( ℩ 𝑐  ∈  𝐶 ( 𝑐  +  𝑑 )  =  ( 𝑎  +  𝑑 ) )  =  𝑎 ) | 
						
							| 15 | 14 | eqcomd | ⊢ ( ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  ∧  ( 𝑑  ∈  𝐷  ∧  ( 𝑎  +  𝑑 )  ∈  𝐵 ) )  →  𝑎  =  ( ℩ 𝑐  ∈  𝐶 ( 𝑐  +  𝑑 )  =  ( 𝑎  +  𝑑 ) ) ) | 
						
							| 16 |  | eqeq2 | ⊢ ( 𝑦  =  ( 𝑎  +  𝑑 )  →  ( ( 𝑐  +  𝑑 )  =  𝑦  ↔  ( 𝑐  +  𝑑 )  =  ( 𝑎  +  𝑑 ) ) ) | 
						
							| 17 | 16 | riotabidv | ⊢ ( 𝑦  =  ( 𝑎  +  𝑑 )  →  ( ℩ 𝑐  ∈  𝐶 ( 𝑐  +  𝑑 )  =  𝑦 )  =  ( ℩ 𝑐  ∈  𝐶 ( 𝑐  +  𝑑 )  =  ( 𝑎  +  𝑑 ) ) ) | 
						
							| 18 | 17 | rspceeqv | ⊢ ( ( ( 𝑎  +  𝑑 )  ∈  𝐵  ∧  𝑎  =  ( ℩ 𝑐  ∈  𝐶 ( 𝑐  +  𝑑 )  =  ( 𝑎  +  𝑑 ) ) )  →  ∃ 𝑦  ∈  𝐵 𝑎  =  ( ℩ 𝑐  ∈  𝐶 ( 𝑐  +  𝑑 )  =  𝑦 ) ) | 
						
							| 19 | 9 15 18 | syl2anc | ⊢ ( ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  ∧  ( 𝑑  ∈  𝐷  ∧  ( 𝑎  +  𝑑 )  ∈  𝐵 ) )  →  ∃ 𝑦  ∈  𝐵 𝑎  =  ( ℩ 𝑐  ∈  𝐶 ( 𝑐  +  𝑑 )  =  𝑦 ) ) | 
						
							| 20 | 7 | adantr | ⊢ ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  →  ¬  𝐷  ≼  𝐴 ) | 
						
							| 21 | 1 | ad2antrr | ⊢ ( ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  ∧  ∀ 𝑑  ∈  𝐷 ¬  ( 𝑎  +  𝑑 )  ∈  𝐵 )  →  𝐴  ∈  𝑉 ) | 
						
							| 22 |  | oveq2 | ⊢ ( 𝑑  =  𝑏  →  ( 𝑎  +  𝑑 )  =  ( 𝑎  +  𝑏 ) ) | 
						
							| 23 | 22 | eleq1d | ⊢ ( 𝑑  =  𝑏  →  ( ( 𝑎  +  𝑑 )  ∈  𝐵  ↔  ( 𝑎  +  𝑏 )  ∈  𝐵 ) ) | 
						
							| 24 | 23 | notbid | ⊢ ( 𝑑  =  𝑏  →  ( ¬  ( 𝑎  +  𝑑 )  ∈  𝐵  ↔  ¬  ( 𝑎  +  𝑏 )  ∈  𝐵 ) ) | 
						
							| 25 | 24 | rspcv | ⊢ ( 𝑏  ∈  𝐷  →  ( ∀ 𝑑  ∈  𝐷 ¬  ( 𝑎  +  𝑑 )  ∈  𝐵  →  ¬  ( 𝑎  +  𝑏 )  ∈  𝐵 ) ) | 
						
							| 26 | 25 | adantl | ⊢ ( ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  ∧  𝑏  ∈  𝐷 )  →  ( ∀ 𝑑  ∈  𝐷 ¬  ( 𝑎  +  𝑑 )  ∈  𝐵  →  ¬  ( 𝑎  +  𝑏 )  ∈  𝐵 ) ) | 
						
							| 27 | 4 | 3expa | ⊢ ( ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  ∧  𝑏  ∈  𝐷 )  →  ( 𝑎  +  𝑏 )  ∈  ( 𝐴  ∪  𝐵 ) ) | 
						
							| 28 |  | elun | ⊢ ( ( 𝑎  +  𝑏 )  ∈  ( 𝐴  ∪  𝐵 )  ↔  ( ( 𝑎  +  𝑏 )  ∈  𝐴  ∨  ( 𝑎  +  𝑏 )  ∈  𝐵 ) ) | 
						
							| 29 | 27 28 | sylib | ⊢ ( ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  ∧  𝑏  ∈  𝐷 )  →  ( ( 𝑎  +  𝑏 )  ∈  𝐴  ∨  ( 𝑎  +  𝑏 )  ∈  𝐵 ) ) | 
						
							| 30 | 29 | orcomd | ⊢ ( ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  ∧  𝑏  ∈  𝐷 )  →  ( ( 𝑎  +  𝑏 )  ∈  𝐵  ∨  ( 𝑎  +  𝑏 )  ∈  𝐴 ) ) | 
						
							| 31 | 30 | ord | ⊢ ( ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  ∧  𝑏  ∈  𝐷 )  →  ( ¬  ( 𝑎  +  𝑏 )  ∈  𝐵  →  ( 𝑎  +  𝑏 )  ∈  𝐴 ) ) | 
						
							| 32 | 26 31 | syld | ⊢ ( ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  ∧  𝑏  ∈  𝐷 )  →  ( ∀ 𝑑  ∈  𝐷 ¬  ( 𝑎  +  𝑑 )  ∈  𝐵  →  ( 𝑎  +  𝑏 )  ∈  𝐴 ) ) | 
						
							| 33 | 32 | impancom | ⊢ ( ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  ∧  ∀ 𝑑  ∈  𝐷 ¬  ( 𝑎  +  𝑑 )  ∈  𝐵 )  →  ( 𝑏  ∈  𝐷  →  ( 𝑎  +  𝑏 )  ∈  𝐴 ) ) | 
						
							| 34 | 5 | ex | ⊢ ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  →  ( ( 𝑏  ∈  𝐷  ∧  𝑐  ∈  𝐷 )  →  ( ( 𝑎  +  𝑏 )  =  ( 𝑎  +  𝑐 )  ↔  𝑏  =  𝑐 ) ) ) | 
						
							| 35 | 34 | adantr | ⊢ ( ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  ∧  ∀ 𝑑  ∈  𝐷 ¬  ( 𝑎  +  𝑑 )  ∈  𝐵 )  →  ( ( 𝑏  ∈  𝐷  ∧  𝑐  ∈  𝐷 )  →  ( ( 𝑎  +  𝑏 )  =  ( 𝑎  +  𝑐 )  ↔  𝑏  =  𝑐 ) ) ) | 
						
							| 36 | 33 35 | dom2d | ⊢ ( ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  ∧  ∀ 𝑑  ∈  𝐷 ¬  ( 𝑎  +  𝑑 )  ∈  𝐵 )  →  ( 𝐴  ∈  𝑉  →  𝐷  ≼  𝐴 ) ) | 
						
							| 37 | 21 36 | mpd | ⊢ ( ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  ∧  ∀ 𝑑  ∈  𝐷 ¬  ( 𝑎  +  𝑑 )  ∈  𝐵 )  →  𝐷  ≼  𝐴 ) | 
						
							| 38 | 20 37 | mtand | ⊢ ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  →  ¬  ∀ 𝑑  ∈  𝐷 ¬  ( 𝑎  +  𝑑 )  ∈  𝐵 ) | 
						
							| 39 |  | dfrex2 | ⊢ ( ∃ 𝑑  ∈  𝐷 ( 𝑎  +  𝑑 )  ∈  𝐵  ↔  ¬  ∀ 𝑑  ∈  𝐷 ¬  ( 𝑎  +  𝑑 )  ∈  𝐵 ) | 
						
							| 40 | 38 39 | sylibr | ⊢ ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  →  ∃ 𝑑  ∈  𝐷 ( 𝑎  +  𝑑 )  ∈  𝐵 ) | 
						
							| 41 | 19 40 | reximddv | ⊢ ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  →  ∃ 𝑑  ∈  𝐷 ∃ 𝑦  ∈  𝐵 𝑎  =  ( ℩ 𝑐  ∈  𝐶 ( 𝑐  +  𝑑 )  =  𝑦 ) ) | 
						
							| 42 |  | vex | ⊢ 𝑑  ∈  V | 
						
							| 43 |  | vex | ⊢ 𝑦  ∈  V | 
						
							| 44 | 42 43 | op1std | ⊢ ( 𝑥  =  〈 𝑑 ,  𝑦 〉  →  ( 1st  ‘ 𝑥 )  =  𝑑 ) | 
						
							| 45 | 44 | oveq2d | ⊢ ( 𝑥  =  〈 𝑑 ,  𝑦 〉  →  ( 𝑐  +  ( 1st  ‘ 𝑥 ) )  =  ( 𝑐  +  𝑑 ) ) | 
						
							| 46 | 42 43 | op2ndd | ⊢ ( 𝑥  =  〈 𝑑 ,  𝑦 〉  →  ( 2nd  ‘ 𝑥 )  =  𝑦 ) | 
						
							| 47 | 45 46 | eqeq12d | ⊢ ( 𝑥  =  〈 𝑑 ,  𝑦 〉  →  ( ( 𝑐  +  ( 1st  ‘ 𝑥 ) )  =  ( 2nd  ‘ 𝑥 )  ↔  ( 𝑐  +  𝑑 )  =  𝑦 ) ) | 
						
							| 48 | 47 | riotabidv | ⊢ ( 𝑥  =  〈 𝑑 ,  𝑦 〉  →  ( ℩ 𝑐  ∈  𝐶 ( 𝑐  +  ( 1st  ‘ 𝑥 ) )  =  ( 2nd  ‘ 𝑥 ) )  =  ( ℩ 𝑐  ∈  𝐶 ( 𝑐  +  𝑑 )  =  𝑦 ) ) | 
						
							| 49 | 48 | eqeq2d | ⊢ ( 𝑥  =  〈 𝑑 ,  𝑦 〉  →  ( 𝑎  =  ( ℩ 𝑐  ∈  𝐶 ( 𝑐  +  ( 1st  ‘ 𝑥 ) )  =  ( 2nd  ‘ 𝑥 ) )  ↔  𝑎  =  ( ℩ 𝑐  ∈  𝐶 ( 𝑐  +  𝑑 )  =  𝑦 ) ) ) | 
						
							| 50 | 49 | rexxp | ⊢ ( ∃ 𝑥  ∈  ( 𝐷  ×  𝐵 ) 𝑎  =  ( ℩ 𝑐  ∈  𝐶 ( 𝑐  +  ( 1st  ‘ 𝑥 ) )  =  ( 2nd  ‘ 𝑥 ) )  ↔  ∃ 𝑑  ∈  𝐷 ∃ 𝑦  ∈  𝐵 𝑎  =  ( ℩ 𝑐  ∈  𝐶 ( 𝑐  +  𝑑 )  =  𝑦 ) ) | 
						
							| 51 | 41 50 | sylibr | ⊢ ( ( 𝜑  ∧  𝑎  ∈  𝐶 )  →  ∃ 𝑥  ∈  ( 𝐷  ×  𝐵 ) 𝑎  =  ( ℩ 𝑐  ∈  𝐶 ( 𝑐  +  ( 1st  ‘ 𝑥 ) )  =  ( 2nd  ‘ 𝑥 ) ) ) | 
						
							| 52 | 8 51 | wdomd | ⊢ ( 𝜑  →  𝐶  ≼*  ( 𝐷  ×  𝐵 ) ) |