| Step | Hyp | Ref | Expression | 
						
							| 1 |  | gonan0 | ⊢ ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ 𝑁 )  →  𝑁  ≠  ∅ ) | 
						
							| 2 | 1 | adantl | ⊢ ( ( 𝑁  ∈  ω  ∧  ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ 𝑁 ) )  →  𝑁  ≠  ∅ ) | 
						
							| 3 |  | nnsuc | ⊢ ( ( 𝑁  ∈  ω  ∧  𝑁  ≠  ∅ )  →  ∃ 𝑥  ∈  ω 𝑁  =  suc  𝑥 ) | 
						
							| 4 |  | suceq | ⊢ ( 𝑑  =  ∅  →  suc  𝑑  =  suc  ∅ ) | 
						
							| 5 | 4 | fveq2d | ⊢ ( 𝑑  =  ∅  →  ( Fmla ‘ suc  𝑑 )  =  ( Fmla ‘ suc  ∅ ) ) | 
						
							| 6 | 5 | eleq2d | ⊢ ( 𝑑  =  ∅  →  ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  𝑑 )  ↔  ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  ∅ ) ) ) | 
						
							| 7 | 5 | eleq2d | ⊢ ( 𝑑  =  ∅  →  ( 𝑎  ∈  ( Fmla ‘ suc  𝑑 )  ↔  𝑎  ∈  ( Fmla ‘ suc  ∅ ) ) ) | 
						
							| 8 | 5 | eleq2d | ⊢ ( 𝑑  =  ∅  →  ( 𝑏  ∈  ( Fmla ‘ suc  𝑑 )  ↔  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) ) | 
						
							| 9 | 7 8 | anbi12d | ⊢ ( 𝑑  =  ∅  →  ( ( 𝑎  ∈  ( Fmla ‘ suc  𝑑 )  ∧  𝑏  ∈  ( Fmla ‘ suc  𝑑 ) )  ↔  ( 𝑎  ∈  ( Fmla ‘ suc  ∅ )  ∧  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) ) ) | 
						
							| 10 | 6 9 | imbi12d | ⊢ ( 𝑑  =  ∅  →  ( ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  𝑑 )  →  ( 𝑎  ∈  ( Fmla ‘ suc  𝑑 )  ∧  𝑏  ∈  ( Fmla ‘ suc  𝑑 ) ) )  ↔  ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  ∅ )  →  ( 𝑎  ∈  ( Fmla ‘ suc  ∅ )  ∧  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) ) ) ) | 
						
							| 11 |  | suceq | ⊢ ( 𝑑  =  𝑐  →  suc  𝑑  =  suc  𝑐 ) | 
						
							| 12 | 11 | fveq2d | ⊢ ( 𝑑  =  𝑐  →  ( Fmla ‘ suc  𝑑 )  =  ( Fmla ‘ suc  𝑐 ) ) | 
						
							| 13 | 12 | eleq2d | ⊢ ( 𝑑  =  𝑐  →  ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  𝑑 )  ↔  ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  𝑐 ) ) ) | 
						
							| 14 | 12 | eleq2d | ⊢ ( 𝑑  =  𝑐  →  ( 𝑎  ∈  ( Fmla ‘ suc  𝑑 )  ↔  𝑎  ∈  ( Fmla ‘ suc  𝑐 ) ) ) | 
						
							| 15 | 12 | eleq2d | ⊢ ( 𝑑  =  𝑐  →  ( 𝑏  ∈  ( Fmla ‘ suc  𝑑 )  ↔  𝑏  ∈  ( Fmla ‘ suc  𝑐 ) ) ) | 
						
							| 16 | 14 15 | anbi12d | ⊢ ( 𝑑  =  𝑐  →  ( ( 𝑎  ∈  ( Fmla ‘ suc  𝑑 )  ∧  𝑏  ∈  ( Fmla ‘ suc  𝑑 ) )  ↔  ( 𝑎  ∈  ( Fmla ‘ suc  𝑐 )  ∧  𝑏  ∈  ( Fmla ‘ suc  𝑐 ) ) ) ) | 
						
							| 17 | 13 16 | imbi12d | ⊢ ( 𝑑  =  𝑐  →  ( ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  𝑑 )  →  ( 𝑎  ∈  ( Fmla ‘ suc  𝑑 )  ∧  𝑏  ∈  ( Fmla ‘ suc  𝑑 ) ) )  ↔  ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  𝑐 )  →  ( 𝑎  ∈  ( Fmla ‘ suc  𝑐 )  ∧  𝑏  ∈  ( Fmla ‘ suc  𝑐 ) ) ) ) ) | 
						
							| 18 |  | suceq | ⊢ ( 𝑑  =  suc  𝑐  →  suc  𝑑  =  suc  suc  𝑐 ) | 
						
							| 19 | 18 | fveq2d | ⊢ ( 𝑑  =  suc  𝑐  →  ( Fmla ‘ suc  𝑑 )  =  ( Fmla ‘ suc  suc  𝑐 ) ) | 
						
							| 20 | 19 | eleq2d | ⊢ ( 𝑑  =  suc  𝑐  →  ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  𝑑 )  ↔  ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  suc  𝑐 ) ) ) | 
						
							| 21 | 19 | eleq2d | ⊢ ( 𝑑  =  suc  𝑐  →  ( 𝑎  ∈  ( Fmla ‘ suc  𝑑 )  ↔  𝑎  ∈  ( Fmla ‘ suc  suc  𝑐 ) ) ) | 
						
							| 22 | 19 | eleq2d | ⊢ ( 𝑑  =  suc  𝑐  →  ( 𝑏  ∈  ( Fmla ‘ suc  𝑑 )  ↔  𝑏  ∈  ( Fmla ‘ suc  suc  𝑐 ) ) ) | 
						
							| 23 | 21 22 | anbi12d | ⊢ ( 𝑑  =  suc  𝑐  →  ( ( 𝑎  ∈  ( Fmla ‘ suc  𝑑 )  ∧  𝑏  ∈  ( Fmla ‘ suc  𝑑 ) )  ↔  ( 𝑎  ∈  ( Fmla ‘ suc  suc  𝑐 )  ∧  𝑏  ∈  ( Fmla ‘ suc  suc  𝑐 ) ) ) ) | 
						
							| 24 | 20 23 | imbi12d | ⊢ ( 𝑑  =  suc  𝑐  →  ( ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  𝑑 )  →  ( 𝑎  ∈  ( Fmla ‘ suc  𝑑 )  ∧  𝑏  ∈  ( Fmla ‘ suc  𝑑 ) ) )  ↔  ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  suc  𝑐 )  →  ( 𝑎  ∈  ( Fmla ‘ suc  suc  𝑐 )  ∧  𝑏  ∈  ( Fmla ‘ suc  suc  𝑐 ) ) ) ) ) | 
						
							| 25 |  | suceq | ⊢ ( 𝑑  =  𝑥  →  suc  𝑑  =  suc  𝑥 ) | 
						
							| 26 | 25 | fveq2d | ⊢ ( 𝑑  =  𝑥  →  ( Fmla ‘ suc  𝑑 )  =  ( Fmla ‘ suc  𝑥 ) ) | 
						
							| 27 | 26 | eleq2d | ⊢ ( 𝑑  =  𝑥  →  ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  𝑑 )  ↔  ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  𝑥 ) ) ) | 
						
							| 28 | 26 | eleq2d | ⊢ ( 𝑑  =  𝑥  →  ( 𝑎  ∈  ( Fmla ‘ suc  𝑑 )  ↔  𝑎  ∈  ( Fmla ‘ suc  𝑥 ) ) ) | 
						
							| 29 | 26 | eleq2d | ⊢ ( 𝑑  =  𝑥  →  ( 𝑏  ∈  ( Fmla ‘ suc  𝑑 )  ↔  𝑏  ∈  ( Fmla ‘ suc  𝑥 ) ) ) | 
						
							| 30 | 28 29 | anbi12d | ⊢ ( 𝑑  =  𝑥  →  ( ( 𝑎  ∈  ( Fmla ‘ suc  𝑑 )  ∧  𝑏  ∈  ( Fmla ‘ suc  𝑑 ) )  ↔  ( 𝑎  ∈  ( Fmla ‘ suc  𝑥 )  ∧  𝑏  ∈  ( Fmla ‘ suc  𝑥 ) ) ) ) | 
						
							| 31 | 27 30 | imbi12d | ⊢ ( 𝑑  =  𝑥  →  ( ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  𝑑 )  →  ( 𝑎  ∈  ( Fmla ‘ suc  𝑑 )  ∧  𝑏  ∈  ( Fmla ‘ suc  𝑑 ) ) )  ↔  ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  𝑥 )  →  ( 𝑎  ∈  ( Fmla ‘ suc  𝑥 )  ∧  𝑏  ∈  ( Fmla ‘ suc  𝑥 ) ) ) ) ) | 
						
							| 32 |  | peano1 | ⊢ ∅  ∈  ω | 
						
							| 33 |  | ovex | ⊢ ( 𝑎 ⊼𝑔 𝑏 )  ∈  V | 
						
							| 34 |  | isfmlasuc | ⊢ ( ( ∅  ∈  ω  ∧  ( 𝑎 ⊼𝑔 𝑏 )  ∈  V )  →  ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  ∅ )  ↔  ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ ∅ )  ∨  ∃ 𝑢  ∈  ( Fmla ‘ ∅ ) ( ∃ 𝑣  ∈  ( Fmla ‘ ∅ ) ( 𝑎 ⊼𝑔 𝑏 )  =  ( 𝑢 ⊼𝑔 𝑣 )  ∨  ∃ 𝑖  ∈  ω ( 𝑎 ⊼𝑔 𝑏 )  =  ∀𝑔 𝑖 𝑢 ) ) ) ) | 
						
							| 35 | 32 33 34 | mp2an | ⊢ ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  ∅ )  ↔  ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ ∅ )  ∨  ∃ 𝑢  ∈  ( Fmla ‘ ∅ ) ( ∃ 𝑣  ∈  ( Fmla ‘ ∅ ) ( 𝑎 ⊼𝑔 𝑏 )  =  ( 𝑢 ⊼𝑔 𝑣 )  ∨  ∃ 𝑖  ∈  ω ( 𝑎 ⊼𝑔 𝑏 )  =  ∀𝑔 𝑖 𝑢 ) ) ) | 
						
							| 36 |  | eqeq1 | ⊢ ( 𝑥  =  ( 𝑎 ⊼𝑔 𝑏 )  →  ( 𝑥  =  ( 𝑖 ∈𝑔 𝑗 )  ↔  ( 𝑎 ⊼𝑔 𝑏 )  =  ( 𝑖 ∈𝑔 𝑗 ) ) ) | 
						
							| 37 | 36 | 2rexbidv | ⊢ ( 𝑥  =  ( 𝑎 ⊼𝑔 𝑏 )  →  ( ∃ 𝑖  ∈  ω ∃ 𝑗  ∈  ω 𝑥  =  ( 𝑖 ∈𝑔 𝑗 )  ↔  ∃ 𝑖  ∈  ω ∃ 𝑗  ∈  ω ( 𝑎 ⊼𝑔 𝑏 )  =  ( 𝑖 ∈𝑔 𝑗 ) ) ) | 
						
							| 38 |  | fmla0 | ⊢ ( Fmla ‘ ∅ )  =  { 𝑥  ∈  V  ∣  ∃ 𝑖  ∈  ω ∃ 𝑗  ∈  ω 𝑥  =  ( 𝑖 ∈𝑔 𝑗 ) } | 
						
							| 39 | 37 38 | elrab2 | ⊢ ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ ∅ )  ↔  ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  V  ∧  ∃ 𝑖  ∈  ω ∃ 𝑗  ∈  ω ( 𝑎 ⊼𝑔 𝑏 )  =  ( 𝑖 ∈𝑔 𝑗 ) ) ) | 
						
							| 40 |  | gonafv | ⊢ ( ( 𝑎  ∈  V  ∧  𝑏  ∈  V )  →  ( 𝑎 ⊼𝑔 𝑏 )  =  〈 1o ,  〈 𝑎 ,  𝑏 〉 〉 ) | 
						
							| 41 | 40 | el2v | ⊢ ( 𝑎 ⊼𝑔 𝑏 )  =  〈 1o ,  〈 𝑎 ,  𝑏 〉 〉 | 
						
							| 42 | 41 | a1i | ⊢ ( ( 𝑖  ∈  ω  ∧  𝑗  ∈  ω )  →  ( 𝑎 ⊼𝑔 𝑏 )  =  〈 1o ,  〈 𝑎 ,  𝑏 〉 〉 ) | 
						
							| 43 |  | goel | ⊢ ( ( 𝑖  ∈  ω  ∧  𝑗  ∈  ω )  →  ( 𝑖 ∈𝑔 𝑗 )  =  〈 ∅ ,  〈 𝑖 ,  𝑗 〉 〉 ) | 
						
							| 44 | 42 43 | eqeq12d | ⊢ ( ( 𝑖  ∈  ω  ∧  𝑗  ∈  ω )  →  ( ( 𝑎 ⊼𝑔 𝑏 )  =  ( 𝑖 ∈𝑔 𝑗 )  ↔  〈 1o ,  〈 𝑎 ,  𝑏 〉 〉  =  〈 ∅ ,  〈 𝑖 ,  𝑗 〉 〉 ) ) | 
						
							| 45 |  | 1oex | ⊢ 1o  ∈  V | 
						
							| 46 |  | opex | ⊢ 〈 𝑎 ,  𝑏 〉  ∈  V | 
						
							| 47 | 45 46 | opth | ⊢ ( 〈 1o ,  〈 𝑎 ,  𝑏 〉 〉  =  〈 ∅ ,  〈 𝑖 ,  𝑗 〉 〉  ↔  ( 1o  =  ∅  ∧  〈 𝑎 ,  𝑏 〉  =  〈 𝑖 ,  𝑗 〉 ) ) | 
						
							| 48 |  | 1n0 | ⊢ 1o  ≠  ∅ | 
						
							| 49 |  | eqneqall | ⊢ ( 1o  =  ∅  →  ( 1o  ≠  ∅  →  ( 𝑎  ∈  ( Fmla ‘ suc  ∅ )  ∧  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) ) ) | 
						
							| 50 | 48 49 | mpi | ⊢ ( 1o  =  ∅  →  ( 𝑎  ∈  ( Fmla ‘ suc  ∅ )  ∧  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) ) | 
						
							| 51 | 50 | adantr | ⊢ ( ( 1o  =  ∅  ∧  〈 𝑎 ,  𝑏 〉  =  〈 𝑖 ,  𝑗 〉 )  →  ( 𝑎  ∈  ( Fmla ‘ suc  ∅ )  ∧  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) ) | 
						
							| 52 | 47 51 | sylbi | ⊢ ( 〈 1o ,  〈 𝑎 ,  𝑏 〉 〉  =  〈 ∅ ,  〈 𝑖 ,  𝑗 〉 〉  →  ( 𝑎  ∈  ( Fmla ‘ suc  ∅ )  ∧  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) ) | 
						
							| 53 | 44 52 | biimtrdi | ⊢ ( ( 𝑖  ∈  ω  ∧  𝑗  ∈  ω )  →  ( ( 𝑎 ⊼𝑔 𝑏 )  =  ( 𝑖 ∈𝑔 𝑗 )  →  ( 𝑎  ∈  ( Fmla ‘ suc  ∅ )  ∧  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) ) ) | 
						
							| 54 | 53 | rexlimdva | ⊢ ( 𝑖  ∈  ω  →  ( ∃ 𝑗  ∈  ω ( 𝑎 ⊼𝑔 𝑏 )  =  ( 𝑖 ∈𝑔 𝑗 )  →  ( 𝑎  ∈  ( Fmla ‘ suc  ∅ )  ∧  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) ) ) | 
						
							| 55 | 54 | rexlimiv | ⊢ ( ∃ 𝑖  ∈  ω ∃ 𝑗  ∈  ω ( 𝑎 ⊼𝑔 𝑏 )  =  ( 𝑖 ∈𝑔 𝑗 )  →  ( 𝑎  ∈  ( Fmla ‘ suc  ∅ )  ∧  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) ) | 
						
							| 56 | 55 | adantl | ⊢ ( ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  V  ∧  ∃ 𝑖  ∈  ω ∃ 𝑗  ∈  ω ( 𝑎 ⊼𝑔 𝑏 )  =  ( 𝑖 ∈𝑔 𝑗 ) )  →  ( 𝑎  ∈  ( Fmla ‘ suc  ∅ )  ∧  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) ) | 
						
							| 57 | 39 56 | sylbi | ⊢ ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ ∅ )  →  ( 𝑎  ∈  ( Fmla ‘ suc  ∅ )  ∧  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) ) | 
						
							| 58 | 41 | a1i | ⊢ ( ( 𝑢  ∈  ( Fmla ‘ ∅ )  ∧  𝑣  ∈  ( Fmla ‘ ∅ ) )  →  ( 𝑎 ⊼𝑔 𝑏 )  =  〈 1o ,  〈 𝑎 ,  𝑏 〉 〉 ) | 
						
							| 59 |  | gonafv | ⊢ ( ( 𝑢  ∈  ( Fmla ‘ ∅ )  ∧  𝑣  ∈  ( Fmla ‘ ∅ ) )  →  ( 𝑢 ⊼𝑔 𝑣 )  =  〈 1o ,  〈 𝑢 ,  𝑣 〉 〉 ) | 
						
							| 60 | 58 59 | eqeq12d | ⊢ ( ( 𝑢  ∈  ( Fmla ‘ ∅ )  ∧  𝑣  ∈  ( Fmla ‘ ∅ ) )  →  ( ( 𝑎 ⊼𝑔 𝑏 )  =  ( 𝑢 ⊼𝑔 𝑣 )  ↔  〈 1o ,  〈 𝑎 ,  𝑏 〉 〉  =  〈 1o ,  〈 𝑢 ,  𝑣 〉 〉 ) ) | 
						
							| 61 | 45 46 | opth | ⊢ ( 〈 1o ,  〈 𝑎 ,  𝑏 〉 〉  =  〈 1o ,  〈 𝑢 ,  𝑣 〉 〉  ↔  ( 1o  =  1o  ∧  〈 𝑎 ,  𝑏 〉  =  〈 𝑢 ,  𝑣 〉 ) ) | 
						
							| 62 |  | vex | ⊢ 𝑎  ∈  V | 
						
							| 63 |  | vex | ⊢ 𝑏  ∈  V | 
						
							| 64 | 62 63 | opth | ⊢ ( 〈 𝑎 ,  𝑏 〉  =  〈 𝑢 ,  𝑣 〉  ↔  ( 𝑎  =  𝑢  ∧  𝑏  =  𝑣 ) ) | 
						
							| 65 |  | simpl | ⊢ ( ( 𝑎  =  𝑢  ∧  𝑏  =  𝑣 )  →  𝑎  =  𝑢 ) | 
						
							| 66 | 65 | equcomd | ⊢ ( ( 𝑎  =  𝑢  ∧  𝑏  =  𝑣 )  →  𝑢  =  𝑎 ) | 
						
							| 67 | 66 | eleq1d | ⊢ ( ( 𝑎  =  𝑢  ∧  𝑏  =  𝑣 )  →  ( 𝑢  ∈  ( Fmla ‘ ∅ )  ↔  𝑎  ∈  ( Fmla ‘ ∅ ) ) ) | 
						
							| 68 |  | simpr | ⊢ ( ( 𝑎  =  𝑢  ∧  𝑏  =  𝑣 )  →  𝑏  =  𝑣 ) | 
						
							| 69 | 68 | equcomd | ⊢ ( ( 𝑎  =  𝑢  ∧  𝑏  =  𝑣 )  →  𝑣  =  𝑏 ) | 
						
							| 70 | 69 | eleq1d | ⊢ ( ( 𝑎  =  𝑢  ∧  𝑏  =  𝑣 )  →  ( 𝑣  ∈  ( Fmla ‘ ∅ )  ↔  𝑏  ∈  ( Fmla ‘ ∅ ) ) ) | 
						
							| 71 | 67 70 | anbi12d | ⊢ ( ( 𝑎  =  𝑢  ∧  𝑏  =  𝑣 )  →  ( ( 𝑢  ∈  ( Fmla ‘ ∅ )  ∧  𝑣  ∈  ( Fmla ‘ ∅ ) )  ↔  ( 𝑎  ∈  ( Fmla ‘ ∅ )  ∧  𝑏  ∈  ( Fmla ‘ ∅ ) ) ) ) | 
						
							| 72 | 64 71 | sylbi | ⊢ ( 〈 𝑎 ,  𝑏 〉  =  〈 𝑢 ,  𝑣 〉  →  ( ( 𝑢  ∈  ( Fmla ‘ ∅ )  ∧  𝑣  ∈  ( Fmla ‘ ∅ ) )  ↔  ( 𝑎  ∈  ( Fmla ‘ ∅ )  ∧  𝑏  ∈  ( Fmla ‘ ∅ ) ) ) ) | 
						
							| 73 | 72 | adantl | ⊢ ( ( 1o  =  1o  ∧  〈 𝑎 ,  𝑏 〉  =  〈 𝑢 ,  𝑣 〉 )  →  ( ( 𝑢  ∈  ( Fmla ‘ ∅ )  ∧  𝑣  ∈  ( Fmla ‘ ∅ ) )  ↔  ( 𝑎  ∈  ( Fmla ‘ ∅ )  ∧  𝑏  ∈  ( Fmla ‘ ∅ ) ) ) ) | 
						
							| 74 | 61 73 | sylbi | ⊢ ( 〈 1o ,  〈 𝑎 ,  𝑏 〉 〉  =  〈 1o ,  〈 𝑢 ,  𝑣 〉 〉  →  ( ( 𝑢  ∈  ( Fmla ‘ ∅ )  ∧  𝑣  ∈  ( Fmla ‘ ∅ ) )  ↔  ( 𝑎  ∈  ( Fmla ‘ ∅ )  ∧  𝑏  ∈  ( Fmla ‘ ∅ ) ) ) ) | 
						
							| 75 |  | fmlasssuc | ⊢ ( ∅  ∈  ω  →  ( Fmla ‘ ∅ )  ⊆  ( Fmla ‘ suc  ∅ ) ) | 
						
							| 76 | 32 75 | ax-mp | ⊢ ( Fmla ‘ ∅ )  ⊆  ( Fmla ‘ suc  ∅ ) | 
						
							| 77 | 76 | sseli | ⊢ ( 𝑎  ∈  ( Fmla ‘ ∅ )  →  𝑎  ∈  ( Fmla ‘ suc  ∅ ) ) | 
						
							| 78 | 76 | sseli | ⊢ ( 𝑏  ∈  ( Fmla ‘ ∅ )  →  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) | 
						
							| 79 | 77 78 | anim12i | ⊢ ( ( 𝑎  ∈  ( Fmla ‘ ∅ )  ∧  𝑏  ∈  ( Fmla ‘ ∅ ) )  →  ( 𝑎  ∈  ( Fmla ‘ suc  ∅ )  ∧  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) ) | 
						
							| 80 | 74 79 | biimtrdi | ⊢ ( 〈 1o ,  〈 𝑎 ,  𝑏 〉 〉  =  〈 1o ,  〈 𝑢 ,  𝑣 〉 〉  →  ( ( 𝑢  ∈  ( Fmla ‘ ∅ )  ∧  𝑣  ∈  ( Fmla ‘ ∅ ) )  →  ( 𝑎  ∈  ( Fmla ‘ suc  ∅ )  ∧  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) ) ) | 
						
							| 81 | 80 | com12 | ⊢ ( ( 𝑢  ∈  ( Fmla ‘ ∅ )  ∧  𝑣  ∈  ( Fmla ‘ ∅ ) )  →  ( 〈 1o ,  〈 𝑎 ,  𝑏 〉 〉  =  〈 1o ,  〈 𝑢 ,  𝑣 〉 〉  →  ( 𝑎  ∈  ( Fmla ‘ suc  ∅ )  ∧  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) ) ) | 
						
							| 82 | 60 81 | sylbid | ⊢ ( ( 𝑢  ∈  ( Fmla ‘ ∅ )  ∧  𝑣  ∈  ( Fmla ‘ ∅ ) )  →  ( ( 𝑎 ⊼𝑔 𝑏 )  =  ( 𝑢 ⊼𝑔 𝑣 )  →  ( 𝑎  ∈  ( Fmla ‘ suc  ∅ )  ∧  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) ) ) | 
						
							| 83 | 82 | rexlimdva | ⊢ ( 𝑢  ∈  ( Fmla ‘ ∅ )  →  ( ∃ 𝑣  ∈  ( Fmla ‘ ∅ ) ( 𝑎 ⊼𝑔 𝑏 )  =  ( 𝑢 ⊼𝑔 𝑣 )  →  ( 𝑎  ∈  ( Fmla ‘ suc  ∅ )  ∧  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) ) ) | 
						
							| 84 |  | gonanegoal | ⊢ ( 𝑎 ⊼𝑔 𝑏 )  ≠  ∀𝑔 𝑖 𝑢 | 
						
							| 85 |  | eqneqall | ⊢ ( ( 𝑎 ⊼𝑔 𝑏 )  =  ∀𝑔 𝑖 𝑢  →  ( ( 𝑎 ⊼𝑔 𝑏 )  ≠  ∀𝑔 𝑖 𝑢  →  ( 𝑎  ∈  ( Fmla ‘ suc  ∅ )  ∧  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) ) ) | 
						
							| 86 | 84 85 | mpi | ⊢ ( ( 𝑎 ⊼𝑔 𝑏 )  =  ∀𝑔 𝑖 𝑢  →  ( 𝑎  ∈  ( Fmla ‘ suc  ∅ )  ∧  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) ) | 
						
							| 87 | 86 | a1i | ⊢ ( ( 𝑢  ∈  ( Fmla ‘ ∅ )  ∧  𝑖  ∈  ω )  →  ( ( 𝑎 ⊼𝑔 𝑏 )  =  ∀𝑔 𝑖 𝑢  →  ( 𝑎  ∈  ( Fmla ‘ suc  ∅ )  ∧  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) ) ) | 
						
							| 88 | 87 | rexlimdva | ⊢ ( 𝑢  ∈  ( Fmla ‘ ∅ )  →  ( ∃ 𝑖  ∈  ω ( 𝑎 ⊼𝑔 𝑏 )  =  ∀𝑔 𝑖 𝑢  →  ( 𝑎  ∈  ( Fmla ‘ suc  ∅ )  ∧  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) ) ) | 
						
							| 89 | 83 88 | jaod | ⊢ ( 𝑢  ∈  ( Fmla ‘ ∅ )  →  ( ( ∃ 𝑣  ∈  ( Fmla ‘ ∅ ) ( 𝑎 ⊼𝑔 𝑏 )  =  ( 𝑢 ⊼𝑔 𝑣 )  ∨  ∃ 𝑖  ∈  ω ( 𝑎 ⊼𝑔 𝑏 )  =  ∀𝑔 𝑖 𝑢 )  →  ( 𝑎  ∈  ( Fmla ‘ suc  ∅ )  ∧  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) ) ) | 
						
							| 90 | 89 | rexlimiv | ⊢ ( ∃ 𝑢  ∈  ( Fmla ‘ ∅ ) ( ∃ 𝑣  ∈  ( Fmla ‘ ∅ ) ( 𝑎 ⊼𝑔 𝑏 )  =  ( 𝑢 ⊼𝑔 𝑣 )  ∨  ∃ 𝑖  ∈  ω ( 𝑎 ⊼𝑔 𝑏 )  =  ∀𝑔 𝑖 𝑢 )  →  ( 𝑎  ∈  ( Fmla ‘ suc  ∅ )  ∧  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) ) | 
						
							| 91 | 57 90 | jaoi | ⊢ ( ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ ∅ )  ∨  ∃ 𝑢  ∈  ( Fmla ‘ ∅ ) ( ∃ 𝑣  ∈  ( Fmla ‘ ∅ ) ( 𝑎 ⊼𝑔 𝑏 )  =  ( 𝑢 ⊼𝑔 𝑣 )  ∨  ∃ 𝑖  ∈  ω ( 𝑎 ⊼𝑔 𝑏 )  =  ∀𝑔 𝑖 𝑢 ) )  →  ( 𝑎  ∈  ( Fmla ‘ suc  ∅ )  ∧  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) ) | 
						
							| 92 | 35 91 | sylbi | ⊢ ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  ∅ )  →  ( 𝑎  ∈  ( Fmla ‘ suc  ∅ )  ∧  𝑏  ∈  ( Fmla ‘ suc  ∅ ) ) ) | 
						
							| 93 |  | gonarlem | ⊢ ( 𝑐  ∈  ω  →  ( ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  𝑐 )  →  ( 𝑎  ∈  ( Fmla ‘ suc  𝑐 )  ∧  𝑏  ∈  ( Fmla ‘ suc  𝑐 ) ) )  →  ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  suc  𝑐 )  →  ( 𝑎  ∈  ( Fmla ‘ suc  suc  𝑐 )  ∧  𝑏  ∈  ( Fmla ‘ suc  suc  𝑐 ) ) ) ) ) | 
						
							| 94 | 10 17 24 31 92 93 | finds | ⊢ ( 𝑥  ∈  ω  →  ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  𝑥 )  →  ( 𝑎  ∈  ( Fmla ‘ suc  𝑥 )  ∧  𝑏  ∈  ( Fmla ‘ suc  𝑥 ) ) ) ) | 
						
							| 95 | 94 | adantr | ⊢ ( ( 𝑥  ∈  ω  ∧  𝑁  =  suc  𝑥 )  →  ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  𝑥 )  →  ( 𝑎  ∈  ( Fmla ‘ suc  𝑥 )  ∧  𝑏  ∈  ( Fmla ‘ suc  𝑥 ) ) ) ) | 
						
							| 96 |  | fveq2 | ⊢ ( 𝑁  =  suc  𝑥  →  ( Fmla ‘ 𝑁 )  =  ( Fmla ‘ suc  𝑥 ) ) | 
						
							| 97 | 96 | eleq2d | ⊢ ( 𝑁  =  suc  𝑥  →  ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ 𝑁 )  ↔  ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  𝑥 ) ) ) | 
						
							| 98 | 96 | eleq2d | ⊢ ( 𝑁  =  suc  𝑥  →  ( 𝑎  ∈  ( Fmla ‘ 𝑁 )  ↔  𝑎  ∈  ( Fmla ‘ suc  𝑥 ) ) ) | 
						
							| 99 | 96 | eleq2d | ⊢ ( 𝑁  =  suc  𝑥  →  ( 𝑏  ∈  ( Fmla ‘ 𝑁 )  ↔  𝑏  ∈  ( Fmla ‘ suc  𝑥 ) ) ) | 
						
							| 100 | 98 99 | anbi12d | ⊢ ( 𝑁  =  suc  𝑥  →  ( ( 𝑎  ∈  ( Fmla ‘ 𝑁 )  ∧  𝑏  ∈  ( Fmla ‘ 𝑁 ) )  ↔  ( 𝑎  ∈  ( Fmla ‘ suc  𝑥 )  ∧  𝑏  ∈  ( Fmla ‘ suc  𝑥 ) ) ) ) | 
						
							| 101 | 97 100 | imbi12d | ⊢ ( 𝑁  =  suc  𝑥  →  ( ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ 𝑁 )  →  ( 𝑎  ∈  ( Fmla ‘ 𝑁 )  ∧  𝑏  ∈  ( Fmla ‘ 𝑁 ) ) )  ↔  ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  𝑥 )  →  ( 𝑎  ∈  ( Fmla ‘ suc  𝑥 )  ∧  𝑏  ∈  ( Fmla ‘ suc  𝑥 ) ) ) ) ) | 
						
							| 102 | 101 | adantl | ⊢ ( ( 𝑥  ∈  ω  ∧  𝑁  =  suc  𝑥 )  →  ( ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ 𝑁 )  →  ( 𝑎  ∈  ( Fmla ‘ 𝑁 )  ∧  𝑏  ∈  ( Fmla ‘ 𝑁 ) ) )  ↔  ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ suc  𝑥 )  →  ( 𝑎  ∈  ( Fmla ‘ suc  𝑥 )  ∧  𝑏  ∈  ( Fmla ‘ suc  𝑥 ) ) ) ) ) | 
						
							| 103 | 95 102 | mpbird | ⊢ ( ( 𝑥  ∈  ω  ∧  𝑁  =  suc  𝑥 )  →  ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ 𝑁 )  →  ( 𝑎  ∈  ( Fmla ‘ 𝑁 )  ∧  𝑏  ∈  ( Fmla ‘ 𝑁 ) ) ) ) | 
						
							| 104 | 103 | rexlimiva | ⊢ ( ∃ 𝑥  ∈  ω 𝑁  =  suc  𝑥  →  ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ 𝑁 )  →  ( 𝑎  ∈  ( Fmla ‘ 𝑁 )  ∧  𝑏  ∈  ( Fmla ‘ 𝑁 ) ) ) ) | 
						
							| 105 | 3 104 | syl | ⊢ ( ( 𝑁  ∈  ω  ∧  𝑁  ≠  ∅ )  →  ( ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ 𝑁 )  →  ( 𝑎  ∈  ( Fmla ‘ 𝑁 )  ∧  𝑏  ∈  ( Fmla ‘ 𝑁 ) ) ) ) | 
						
							| 106 | 105 | impancom | ⊢ ( ( 𝑁  ∈  ω  ∧  ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ 𝑁 ) )  →  ( 𝑁  ≠  ∅  →  ( 𝑎  ∈  ( Fmla ‘ 𝑁 )  ∧  𝑏  ∈  ( Fmla ‘ 𝑁 ) ) ) ) | 
						
							| 107 | 2 106 | mpd | ⊢ ( ( 𝑁  ∈  ω  ∧  ( 𝑎 ⊼𝑔 𝑏 )  ∈  ( Fmla ‘ 𝑁 ) )  →  ( 𝑎  ∈  ( Fmla ‘ 𝑁 )  ∧  𝑏  ∈  ( Fmla ‘ 𝑁 ) ) ) |