| Step | Hyp | Ref | Expression | 
						
							| 1 |  | fzindd.1 | ⊢ ( 𝑥  =  𝑀  →  ( 𝜓  ↔  𝜒 ) ) | 
						
							| 2 |  | fzindd.2 | ⊢ ( 𝑥  =  𝑦  →  ( 𝜓  ↔  𝜃 ) ) | 
						
							| 3 |  | fzindd.3 | ⊢ ( 𝑥  =  ( 𝑦  +  1 )  →  ( 𝜓  ↔  𝜏 ) ) | 
						
							| 4 |  | fzindd.4 | ⊢ ( 𝑥  =  𝐴  →  ( 𝜓  ↔  𝜂 ) ) | 
						
							| 5 |  | fzindd.5 | ⊢ ( 𝜑  →  𝜒 ) | 
						
							| 6 |  | fzindd.6 | ⊢ ( ( 𝜑  ∧  ( 𝑦  ∈  ℤ  ∧  𝑀  ≤  𝑦  ∧  𝑦  <  𝑁 )  ∧  𝜃 )  →  𝜏 ) | 
						
							| 7 |  | fzindd.7 | ⊢ ( 𝜑  →  𝑀  ∈  ℤ ) | 
						
							| 8 |  | fzindd.8 | ⊢ ( 𝜑  →  𝑁  ∈  ℤ ) | 
						
							| 9 |  | fzindd.9 | ⊢ ( 𝜑  →  𝑀  ≤  𝑁 ) | 
						
							| 10 | 7 8 | jca | ⊢ ( 𝜑  →  ( 𝑀  ∈  ℤ  ∧  𝑁  ∈  ℤ ) ) | 
						
							| 11 | 1 | imbi2d | ⊢ ( 𝑥  =  𝑀  →  ( ( 𝜑  →  𝜓 )  ↔  ( 𝜑  →  𝜒 ) ) ) | 
						
							| 12 | 2 | imbi2d | ⊢ ( 𝑥  =  𝑦  →  ( ( 𝜑  →  𝜓 )  ↔  ( 𝜑  →  𝜃 ) ) ) | 
						
							| 13 | 3 | imbi2d | ⊢ ( 𝑥  =  ( 𝑦  +  1 )  →  ( ( 𝜑  →  𝜓 )  ↔  ( 𝜑  →  𝜏 ) ) ) | 
						
							| 14 | 4 | imbi2d | ⊢ ( 𝑥  =  𝐴  →  ( ( 𝜑  →  𝜓 )  ↔  ( 𝜑  →  𝜂 ) ) ) | 
						
							| 15 | 5 | a1i | ⊢ ( ( 𝑀  ∈  ℤ  ∧  𝑁  ∈  ℤ  ∧  𝑀  ≤  𝑁 )  →  ( 𝜑  →  𝜒 ) ) | 
						
							| 16 | 6 | 3expa | ⊢ ( ( ( 𝜑  ∧  ( 𝑦  ∈  ℤ  ∧  𝑀  ≤  𝑦  ∧  𝑦  <  𝑁 ) )  ∧  𝜃 )  →  𝜏 ) | 
						
							| 17 | 16 | ex | ⊢ ( ( 𝜑  ∧  ( 𝑦  ∈  ℤ  ∧  𝑀  ≤  𝑦  ∧  𝑦  <  𝑁 ) )  →  ( 𝜃  →  𝜏 ) ) | 
						
							| 18 | 17 | expcom | ⊢ ( ( 𝑦  ∈  ℤ  ∧  𝑀  ≤  𝑦  ∧  𝑦  <  𝑁 )  →  ( 𝜑  →  ( 𝜃  →  𝜏 ) ) ) | 
						
							| 19 | 18 | a2d | ⊢ ( ( 𝑦  ∈  ℤ  ∧  𝑀  ≤  𝑦  ∧  𝑦  <  𝑁 )  →  ( ( 𝜑  →  𝜃 )  →  ( 𝜑  →  𝜏 ) ) ) | 
						
							| 20 | 19 | adantl | ⊢ ( ( ( 𝑀  ∈  ℤ  ∧  𝑁  ∈  ℤ )  ∧  ( 𝑦  ∈  ℤ  ∧  𝑀  ≤  𝑦  ∧  𝑦  <  𝑁 ) )  →  ( ( 𝜑  →  𝜃 )  →  ( 𝜑  →  𝜏 ) ) ) | 
						
							| 21 | 11 12 13 14 15 20 | fzind | ⊢ ( ( ( 𝑀  ∈  ℤ  ∧  𝑁  ∈  ℤ )  ∧  ( 𝐴  ∈  ℤ  ∧  𝑀  ≤  𝐴  ∧  𝐴  ≤  𝑁 ) )  →  ( 𝜑  →  𝜂 ) ) | 
						
							| 22 | 10 21 | sylan | ⊢ ( ( 𝜑  ∧  ( 𝐴  ∈  ℤ  ∧  𝑀  ≤  𝐴  ∧  𝐴  ≤  𝑁 ) )  →  ( 𝜑  →  𝜂 ) ) | 
						
							| 23 | 22 | imp | ⊢ ( ( ( 𝜑  ∧  ( 𝐴  ∈  ℤ  ∧  𝑀  ≤  𝐴  ∧  𝐴  ≤  𝑁 ) )  ∧  𝜑 )  →  𝜂 ) | 
						
							| 24 | 23 | anabss1 | ⊢ ( ( 𝜑  ∧  ( 𝐴  ∈  ℤ  ∧  𝑀  ≤  𝐴  ∧  𝐴  ≤  𝑁 ) )  →  𝜂 ) |