| Step | Hyp | Ref | Expression | 
						
							| 1 |  | ianor | ⊢ ( ¬  ( 𝐹  ∈  ℕ0  ∧  𝐿  ∈  ℕ0 )  ↔  ( ¬  𝐹  ∈  ℕ0  ∨  ¬  𝐿  ∈  ℕ0 ) ) | 
						
							| 2 |  | ianor | ⊢ ( ¬  ( 𝐹  ∈  ℤ  ∧  0  ≤  𝐹 )  ↔  ( ¬  𝐹  ∈  ℤ  ∨  ¬  0  ≤  𝐹 ) ) | 
						
							| 3 |  | elnn0z | ⊢ ( 𝐹  ∈  ℕ0  ↔  ( 𝐹  ∈  ℤ  ∧  0  ≤  𝐹 ) ) | 
						
							| 4 | 2 3 | xchnxbir | ⊢ ( ¬  𝐹  ∈  ℕ0  ↔  ( ¬  𝐹  ∈  ℤ  ∨  ¬  0  ≤  𝐹 ) ) | 
						
							| 5 |  | ianor | ⊢ ( ¬  ( 𝐿  ∈  ℤ  ∧  0  ≤  𝐿 )  ↔  ( ¬  𝐿  ∈  ℤ  ∨  ¬  0  ≤  𝐿 ) ) | 
						
							| 6 |  | elnn0z | ⊢ ( 𝐿  ∈  ℕ0  ↔  ( 𝐿  ∈  ℤ  ∧  0  ≤  𝐿 ) ) | 
						
							| 7 | 5 6 | xchnxbir | ⊢ ( ¬  𝐿  ∈  ℕ0  ↔  ( ¬  𝐿  ∈  ℤ  ∨  ¬  0  ≤  𝐿 ) ) | 
						
							| 8 | 4 7 | orbi12i | ⊢ ( ( ¬  𝐹  ∈  ℕ0  ∨  ¬  𝐿  ∈  ℕ0 )  ↔  ( ( ¬  𝐹  ∈  ℤ  ∨  ¬  0  ≤  𝐹 )  ∨  ( ¬  𝐿  ∈  ℤ  ∨  ¬  0  ≤  𝐿 ) ) ) | 
						
							| 9 |  | or4 | ⊢ ( ( ( ¬  𝐹  ∈  ℤ  ∨  ¬  0  ≤  𝐹 )  ∨  ( ¬  𝐿  ∈  ℤ  ∨  ¬  0  ≤  𝐿 ) )  ↔  ( ( ¬  𝐹  ∈  ℤ  ∨  ¬  𝐿  ∈  ℤ )  ∨  ( ¬  0  ≤  𝐹  ∨  ¬  0  ≤  𝐿 ) ) ) | 
						
							| 10 |  | ianor | ⊢ ( ¬  ( 𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  ↔  ( ¬  𝐹  ∈  ℤ  ∨  ¬  𝐿  ∈  ℤ ) ) | 
						
							| 11 | 10 | bicomi | ⊢ ( ( ¬  𝐹  ∈  ℤ  ∨  ¬  𝐿  ∈  ℤ )  ↔  ¬  ( 𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ ) ) | 
						
							| 12 | 11 | orbi1i | ⊢ ( ( ( ¬  𝐹  ∈  ℤ  ∨  ¬  𝐿  ∈  ℤ )  ∨  ( ¬  0  ≤  𝐹  ∨  ¬  0  ≤  𝐿 ) )  ↔  ( ¬  ( 𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  ∨  ( ¬  0  ≤  𝐹  ∨  ¬  0  ≤  𝐿 ) ) ) | 
						
							| 13 | 9 12 | bitri | ⊢ ( ( ( ¬  𝐹  ∈  ℤ  ∨  ¬  0  ≤  𝐹 )  ∨  ( ¬  𝐿  ∈  ℤ  ∨  ¬  0  ≤  𝐿 ) )  ↔  ( ¬  ( 𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  ∨  ( ¬  0  ≤  𝐹  ∨  ¬  0  ≤  𝐿 ) ) ) | 
						
							| 14 | 8 13 | bitri | ⊢ ( ( ¬  𝐹  ∈  ℕ0  ∨  ¬  𝐿  ∈  ℕ0 )  ↔  ( ¬  ( 𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  ∨  ( ¬  0  ≤  𝐹  ∨  ¬  0  ≤  𝐿 ) ) ) | 
						
							| 15 | 1 14 | bitri | ⊢ ( ¬  ( 𝐹  ∈  ℕ0  ∧  𝐿  ∈  ℕ0 )  ↔  ( ¬  ( 𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  ∨  ( ¬  0  ≤  𝐹  ∨  ¬  0  ≤  𝐿 ) ) ) | 
						
							| 16 |  | swrdnznd | ⊢ ( ¬  ( 𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  →  ( 𝑆  substr  〈 𝐹 ,  𝐿 〉 )  =  ∅ ) | 
						
							| 17 | 16 | a1d | ⊢ ( ¬  ( 𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  →  ( 𝑆  ∈  Word  𝑉  →  ( 𝑆  substr  〈 𝐹 ,  𝐿 〉 )  =  ∅ ) ) | 
						
							| 18 |  | notnotb | ⊢ ( ( 𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  ↔  ¬  ¬  ( 𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ ) ) | 
						
							| 19 |  | zre | ⊢ ( 𝐹  ∈  ℤ  →  𝐹  ∈  ℝ ) | 
						
							| 20 |  | 0red | ⊢ ( 𝐹  ∈  ℤ  →  0  ∈  ℝ ) | 
						
							| 21 | 19 20 | jca | ⊢ ( 𝐹  ∈  ℤ  →  ( 𝐹  ∈  ℝ  ∧  0  ∈  ℝ ) ) | 
						
							| 22 | 21 | 3ad2ant2 | ⊢ ( ( 𝑆  ∈  Word  𝑉  ∧  𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  →  ( 𝐹  ∈  ℝ  ∧  0  ∈  ℝ ) ) | 
						
							| 23 |  | ltnle | ⊢ ( ( 𝐹  ∈  ℝ  ∧  0  ∈  ℝ )  →  ( 𝐹  <  0  ↔  ¬  0  ≤  𝐹 ) ) | 
						
							| 24 | 22 23 | syl | ⊢ ( ( 𝑆  ∈  Word  𝑉  ∧  𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  →  ( 𝐹  <  0  ↔  ¬  0  ≤  𝐹 ) ) | 
						
							| 25 |  | orc | ⊢ ( 𝐹  <  0  →  ( 𝐹  <  0  ∨  𝐿  ≤  𝐹 ) ) | 
						
							| 26 | 24 25 | biimtrrdi | ⊢ ( ( 𝑆  ∈  Word  𝑉  ∧  𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  →  ( ¬  0  ≤  𝐹  →  ( 𝐹  <  0  ∨  𝐿  ≤  𝐹 ) ) ) | 
						
							| 27 | 26 | com12 | ⊢ ( ¬  0  ≤  𝐹  →  ( ( 𝑆  ∈  Word  𝑉  ∧  𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  →  ( 𝐹  <  0  ∨  𝐿  ≤  𝐹 ) ) ) | 
						
							| 28 |  | notnotb | ⊢ ( 0  ≤  𝐹  ↔  ¬  ¬  0  ≤  𝐹 ) | 
						
							| 29 | 28 | a1i | ⊢ ( ( 𝑆  ∈  Word  𝑉  ∧  𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  →  ( 0  ≤  𝐹  ↔  ¬  ¬  0  ≤  𝐹 ) ) | 
						
							| 30 |  | zre | ⊢ ( 𝐿  ∈  ℤ  →  𝐿  ∈  ℝ ) | 
						
							| 31 |  | 0red | ⊢ ( 𝐿  ∈  ℤ  →  0  ∈  ℝ ) | 
						
							| 32 | 30 31 | jca | ⊢ ( 𝐿  ∈  ℤ  →  ( 𝐿  ∈  ℝ  ∧  0  ∈  ℝ ) ) | 
						
							| 33 | 32 | 3ad2ant3 | ⊢ ( ( 𝑆  ∈  Word  𝑉  ∧  𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  →  ( 𝐿  ∈  ℝ  ∧  0  ∈  ℝ ) ) | 
						
							| 34 |  | ltnle | ⊢ ( ( 𝐿  ∈  ℝ  ∧  0  ∈  ℝ )  →  ( 𝐿  <  0  ↔  ¬  0  ≤  𝐿 ) ) | 
						
							| 35 | 33 34 | syl | ⊢ ( ( 𝑆  ∈  Word  𝑉  ∧  𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  →  ( 𝐿  <  0  ↔  ¬  0  ≤  𝐿 ) ) | 
						
							| 36 | 29 35 | anbi12d | ⊢ ( ( 𝑆  ∈  Word  𝑉  ∧  𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  →  ( ( 0  ≤  𝐹  ∧  𝐿  <  0 )  ↔  ( ¬  ¬  0  ≤  𝐹  ∧  ¬  0  ≤  𝐿 ) ) ) | 
						
							| 37 | 30 | 3ad2ant3 | ⊢ ( ( 𝑆  ∈  Word  𝑉  ∧  𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  →  𝐿  ∈  ℝ ) | 
						
							| 38 |  | 0red | ⊢ ( ( 𝑆  ∈  Word  𝑉  ∧  𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  →  0  ∈  ℝ ) | 
						
							| 39 | 19 | 3ad2ant2 | ⊢ ( ( 𝑆  ∈  Word  𝑉  ∧  𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  →  𝐹  ∈  ℝ ) | 
						
							| 40 |  | ltleletr | ⊢ ( ( 𝐿  ∈  ℝ  ∧  0  ∈  ℝ  ∧  𝐹  ∈  ℝ )  →  ( ( 𝐿  <  0  ∧  0  ≤  𝐹 )  →  𝐿  ≤  𝐹 ) ) | 
						
							| 41 | 37 38 39 40 | syl3anc | ⊢ ( ( 𝑆  ∈  Word  𝑉  ∧  𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  →  ( ( 𝐿  <  0  ∧  0  ≤  𝐹 )  →  𝐿  ≤  𝐹 ) ) | 
						
							| 42 |  | olc | ⊢ ( 𝐿  ≤  𝐹  →  ( 𝐹  <  0  ∨  𝐿  ≤  𝐹 ) ) | 
						
							| 43 | 41 42 | syl6 | ⊢ ( ( 𝑆  ∈  Word  𝑉  ∧  𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  →  ( ( 𝐿  <  0  ∧  0  ≤  𝐹 )  →  ( 𝐹  <  0  ∨  𝐿  ≤  𝐹 ) ) ) | 
						
							| 44 | 43 | ancomsd | ⊢ ( ( 𝑆  ∈  Word  𝑉  ∧  𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  →  ( ( 0  ≤  𝐹  ∧  𝐿  <  0 )  →  ( 𝐹  <  0  ∨  𝐿  ≤  𝐹 ) ) ) | 
						
							| 45 | 36 44 | sylbird | ⊢ ( ( 𝑆  ∈  Word  𝑉  ∧  𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  →  ( ( ¬  ¬  0  ≤  𝐹  ∧  ¬  0  ≤  𝐿 )  →  ( 𝐹  <  0  ∨  𝐿  ≤  𝐹 ) ) ) | 
						
							| 46 | 45 | com12 | ⊢ ( ( ¬  ¬  0  ≤  𝐹  ∧  ¬  0  ≤  𝐿 )  →  ( ( 𝑆  ∈  Word  𝑉  ∧  𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  →  ( 𝐹  <  0  ∨  𝐿  ≤  𝐹 ) ) ) | 
						
							| 47 | 27 46 | jaoi3 | ⊢ ( ( ¬  0  ≤  𝐹  ∨  ¬  0  ≤  𝐿 )  →  ( ( 𝑆  ∈  Word  𝑉  ∧  𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  →  ( 𝐹  <  0  ∨  𝐿  ≤  𝐹 ) ) ) | 
						
							| 48 | 47 | impcom | ⊢ ( ( ( 𝑆  ∈  Word  𝑉  ∧  𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  ∧  ( ¬  0  ≤  𝐹  ∨  ¬  0  ≤  𝐿 ) )  →  ( 𝐹  <  0  ∨  𝐿  ≤  𝐹 ) ) | 
						
							| 49 | 48 | orcd | ⊢ ( ( ( 𝑆  ∈  Word  𝑉  ∧  𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  ∧  ( ¬  0  ≤  𝐹  ∨  ¬  0  ≤  𝐿 ) )  →  ( ( 𝐹  <  0  ∨  𝐿  ≤  𝐹 )  ∨  ( ♯ ‘ 𝑆 )  <  𝐿 ) ) | 
						
							| 50 |  | df-3or | ⊢ ( ( 𝐹  <  0  ∨  𝐿  ≤  𝐹  ∨  ( ♯ ‘ 𝑆 )  <  𝐿 )  ↔  ( ( 𝐹  <  0  ∨  𝐿  ≤  𝐹 )  ∨  ( ♯ ‘ 𝑆 )  <  𝐿 ) ) | 
						
							| 51 | 49 50 | sylibr | ⊢ ( ( ( 𝑆  ∈  Word  𝑉  ∧  𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  ∧  ( ¬  0  ≤  𝐹  ∨  ¬  0  ≤  𝐿 ) )  →  ( 𝐹  <  0  ∨  𝐿  ≤  𝐹  ∨  ( ♯ ‘ 𝑆 )  <  𝐿 ) ) | 
						
							| 52 |  | swrdnd | ⊢ ( ( 𝑆  ∈  Word  𝑉  ∧  𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  →  ( ( 𝐹  <  0  ∨  𝐿  ≤  𝐹  ∨  ( ♯ ‘ 𝑆 )  <  𝐿 )  →  ( 𝑆  substr  〈 𝐹 ,  𝐿 〉 )  =  ∅ ) ) | 
						
							| 53 | 52 | imp | ⊢ ( ( ( 𝑆  ∈  Word  𝑉  ∧  𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  ∧  ( 𝐹  <  0  ∨  𝐿  ≤  𝐹  ∨  ( ♯ ‘ 𝑆 )  <  𝐿 ) )  →  ( 𝑆  substr  〈 𝐹 ,  𝐿 〉 )  =  ∅ ) | 
						
							| 54 | 51 53 | syldan | ⊢ ( ( ( 𝑆  ∈  Word  𝑉  ∧  𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  ∧  ( ¬  0  ≤  𝐹  ∨  ¬  0  ≤  𝐿 ) )  →  ( 𝑆  substr  〈 𝐹 ,  𝐿 〉 )  =  ∅ ) | 
						
							| 55 | 54 | ex | ⊢ ( ( 𝑆  ∈  Word  𝑉  ∧  𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  →  ( ( ¬  0  ≤  𝐹  ∨  ¬  0  ≤  𝐿 )  →  ( 𝑆  substr  〈 𝐹 ,  𝐿 〉 )  =  ∅ ) ) | 
						
							| 56 | 55 | 3expb | ⊢ ( ( 𝑆  ∈  Word  𝑉  ∧  ( 𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ ) )  →  ( ( ¬  0  ≤  𝐹  ∨  ¬  0  ≤  𝐿 )  →  ( 𝑆  substr  〈 𝐹 ,  𝐿 〉 )  =  ∅ ) ) | 
						
							| 57 | 56 | expcom | ⊢ ( ( 𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  →  ( 𝑆  ∈  Word  𝑉  →  ( ( ¬  0  ≤  𝐹  ∨  ¬  0  ≤  𝐿 )  →  ( 𝑆  substr  〈 𝐹 ,  𝐿 〉 )  =  ∅ ) ) ) | 
						
							| 58 | 57 | com23 | ⊢ ( ( 𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  →  ( ( ¬  0  ≤  𝐹  ∨  ¬  0  ≤  𝐿 )  →  ( 𝑆  ∈  Word  𝑉  →  ( 𝑆  substr  〈 𝐹 ,  𝐿 〉 )  =  ∅ ) ) ) | 
						
							| 59 | 18 58 | sylbir | ⊢ ( ¬  ¬  ( 𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  →  ( ( ¬  0  ≤  𝐹  ∨  ¬  0  ≤  𝐿 )  →  ( 𝑆  ∈  Word  𝑉  →  ( 𝑆  substr  〈 𝐹 ,  𝐿 〉 )  =  ∅ ) ) ) | 
						
							| 60 | 59 | imp | ⊢ ( ( ¬  ¬  ( 𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  ∧  ( ¬  0  ≤  𝐹  ∨  ¬  0  ≤  𝐿 ) )  →  ( 𝑆  ∈  Word  𝑉  →  ( 𝑆  substr  〈 𝐹 ,  𝐿 〉 )  =  ∅ ) ) | 
						
							| 61 | 17 60 | jaoi3 | ⊢ ( ( ¬  ( 𝐹  ∈  ℤ  ∧  𝐿  ∈  ℤ )  ∨  ( ¬  0  ≤  𝐹  ∨  ¬  0  ≤  𝐿 ) )  →  ( 𝑆  ∈  Word  𝑉  →  ( 𝑆  substr  〈 𝐹 ,  𝐿 〉 )  =  ∅ ) ) | 
						
							| 62 | 15 61 | sylbi | ⊢ ( ¬  ( 𝐹  ∈  ℕ0  ∧  𝐿  ∈  ℕ0 )  →  ( 𝑆  ∈  Word  𝑉  →  ( 𝑆  substr  〈 𝐹 ,  𝐿 〉 )  =  ∅ ) ) | 
						
							| 63 | 62 | impcom | ⊢ ( ( 𝑆  ∈  Word  𝑉  ∧  ¬  ( 𝐹  ∈  ℕ0  ∧  𝐿  ∈  ℕ0 ) )  →  ( 𝑆  substr  〈 𝐹 ,  𝐿 〉 )  =  ∅ ) |