| Step | Hyp | Ref | Expression | 
						
							| 1 |  | structfn.1 | ⊢ 𝐹  Struct  〈 𝑀 ,  𝑁 〉 | 
						
							| 2 | 1 | structfun | ⊢ Fun  ◡ ◡ 𝐹 | 
						
							| 3 |  | isstruct | ⊢ ( 𝐹  Struct  〈 𝑀 ,  𝑁 〉  ↔  ( ( 𝑀  ∈  ℕ  ∧  𝑁  ∈  ℕ  ∧  𝑀  ≤  𝑁 )  ∧  Fun  ( 𝐹  ∖  { ∅ } )  ∧  dom  𝐹  ⊆  ( 𝑀 ... 𝑁 ) ) ) | 
						
							| 4 | 1 3 | mpbi | ⊢ ( ( 𝑀  ∈  ℕ  ∧  𝑁  ∈  ℕ  ∧  𝑀  ≤  𝑁 )  ∧  Fun  ( 𝐹  ∖  { ∅ } )  ∧  dom  𝐹  ⊆  ( 𝑀 ... 𝑁 ) ) | 
						
							| 5 | 4 | simp3i | ⊢ dom  𝐹  ⊆  ( 𝑀 ... 𝑁 ) | 
						
							| 6 | 4 | simp1i | ⊢ ( 𝑀  ∈  ℕ  ∧  𝑁  ∈  ℕ  ∧  𝑀  ≤  𝑁 ) | 
						
							| 7 | 6 | simp1i | ⊢ 𝑀  ∈  ℕ | 
						
							| 8 |  | elnnuz | ⊢ ( 𝑀  ∈  ℕ  ↔  𝑀  ∈  ( ℤ≥ ‘ 1 ) ) | 
						
							| 9 | 7 8 | mpbi | ⊢ 𝑀  ∈  ( ℤ≥ ‘ 1 ) | 
						
							| 10 |  | fzss1 | ⊢ ( 𝑀  ∈  ( ℤ≥ ‘ 1 )  →  ( 𝑀 ... 𝑁 )  ⊆  ( 1 ... 𝑁 ) ) | 
						
							| 11 | 9 10 | ax-mp | ⊢ ( 𝑀 ... 𝑁 )  ⊆  ( 1 ... 𝑁 ) | 
						
							| 12 | 5 11 | sstri | ⊢ dom  𝐹  ⊆  ( 1 ... 𝑁 ) | 
						
							| 13 | 2 12 | pm3.2i | ⊢ ( Fun  ◡ ◡ 𝐹  ∧  dom  𝐹  ⊆  ( 1 ... 𝑁 ) ) |