| Step | Hyp | Ref | Expression | 
						
							| 1 |  | peano2uz | ⊢ ( 𝑁  ∈  ( ℤ≥ ‘ 𝐾 )  →  ( 𝑁  +  1 )  ∈  ( ℤ≥ ‘ 𝐾 ) ) | 
						
							| 2 |  | eluzelre | ⊢ ( 𝑁  ∈  ( ℤ≥ ‘ 𝑀 )  →  𝑁  ∈  ℝ ) | 
						
							| 3 |  | ltp1 | ⊢ ( 𝑁  ∈  ℝ  →  𝑁  <  ( 𝑁  +  1 ) ) | 
						
							| 4 |  | peano2re | ⊢ ( 𝑁  ∈  ℝ  →  ( 𝑁  +  1 )  ∈  ℝ ) | 
						
							| 5 |  | ltnle | ⊢ ( ( 𝑁  ∈  ℝ  ∧  ( 𝑁  +  1 )  ∈  ℝ )  →  ( 𝑁  <  ( 𝑁  +  1 )  ↔  ¬  ( 𝑁  +  1 )  ≤  𝑁 ) ) | 
						
							| 6 | 4 5 | mpdan | ⊢ ( 𝑁  ∈  ℝ  →  ( 𝑁  <  ( 𝑁  +  1 )  ↔  ¬  ( 𝑁  +  1 )  ≤  𝑁 ) ) | 
						
							| 7 | 3 6 | mpbid | ⊢ ( 𝑁  ∈  ℝ  →  ¬  ( 𝑁  +  1 )  ≤  𝑁 ) | 
						
							| 8 | 2 7 | syl | ⊢ ( 𝑁  ∈  ( ℤ≥ ‘ 𝑀 )  →  ¬  ( 𝑁  +  1 )  ≤  𝑁 ) | 
						
							| 9 |  | elfzle2 | ⊢ ( ( 𝑁  +  1 )  ∈  ( 𝑀 ... 𝑁 )  →  ( 𝑁  +  1 )  ≤  𝑁 ) | 
						
							| 10 | 8 9 | nsyl | ⊢ ( 𝑁  ∈  ( ℤ≥ ‘ 𝑀 )  →  ¬  ( 𝑁  +  1 )  ∈  ( 𝑀 ... 𝑁 ) ) | 
						
							| 11 | 10 | ad2antrr | ⊢ ( ( ( 𝑁  ∈  ( ℤ≥ ‘ 𝑀 )  ∧  𝐾  ∈  ℤ )  ∧  𝑁  ∈  ( ℤ≥ ‘ 𝐾 ) )  →  ¬  ( 𝑁  +  1 )  ∈  ( 𝑀 ... 𝑁 ) ) | 
						
							| 12 |  | nelneq2 | ⊢ ( ( ( 𝑁  +  1 )  ∈  ( ℤ≥ ‘ 𝐾 )  ∧  ¬  ( 𝑁  +  1 )  ∈  ( 𝑀 ... 𝑁 ) )  →  ¬  ( ℤ≥ ‘ 𝐾 )  =  ( 𝑀 ... 𝑁 ) ) | 
						
							| 13 | 1 11 12 | syl2an2 | ⊢ ( ( ( 𝑁  ∈  ( ℤ≥ ‘ 𝑀 )  ∧  𝐾  ∈  ℤ )  ∧  𝑁  ∈  ( ℤ≥ ‘ 𝐾 ) )  →  ¬  ( ℤ≥ ‘ 𝐾 )  =  ( 𝑀 ... 𝑁 ) ) | 
						
							| 14 |  | eqcom | ⊢ ( ( ℤ≥ ‘ 𝐾 )  =  ( 𝑀 ... 𝑁 )  ↔  ( 𝑀 ... 𝑁 )  =  ( ℤ≥ ‘ 𝐾 ) ) | 
						
							| 15 | 13 14 | sylnib | ⊢ ( ( ( 𝑁  ∈  ( ℤ≥ ‘ 𝑀 )  ∧  𝐾  ∈  ℤ )  ∧  𝑁  ∈  ( ℤ≥ ‘ 𝐾 ) )  →  ¬  ( 𝑀 ... 𝑁 )  =  ( ℤ≥ ‘ 𝐾 ) ) | 
						
							| 16 |  | eluzfz2 | ⊢ ( 𝑁  ∈  ( ℤ≥ ‘ 𝑀 )  →  𝑁  ∈  ( 𝑀 ... 𝑁 ) ) | 
						
							| 17 | 16 | ad2antrr | ⊢ ( ( ( 𝑁  ∈  ( ℤ≥ ‘ 𝑀 )  ∧  𝐾  ∈  ℤ )  ∧  ¬  𝑁  ∈  ( ℤ≥ ‘ 𝐾 ) )  →  𝑁  ∈  ( 𝑀 ... 𝑁 ) ) | 
						
							| 18 |  | nelneq2 | ⊢ ( ( 𝑁  ∈  ( 𝑀 ... 𝑁 )  ∧  ¬  𝑁  ∈  ( ℤ≥ ‘ 𝐾 ) )  →  ¬  ( 𝑀 ... 𝑁 )  =  ( ℤ≥ ‘ 𝐾 ) ) | 
						
							| 19 | 17 18 | sylancom | ⊢ ( ( ( 𝑁  ∈  ( ℤ≥ ‘ 𝑀 )  ∧  𝐾  ∈  ℤ )  ∧  ¬  𝑁  ∈  ( ℤ≥ ‘ 𝐾 ) )  →  ¬  ( 𝑀 ... 𝑁 )  =  ( ℤ≥ ‘ 𝐾 ) ) | 
						
							| 20 | 15 19 | pm2.61dan | ⊢ ( ( 𝑁  ∈  ( ℤ≥ ‘ 𝑀 )  ∧  𝐾  ∈  ℤ )  →  ¬  ( 𝑀 ... 𝑁 )  =  ( ℤ≥ ‘ 𝐾 ) ) |