| Step | Hyp | Ref | Expression | 
						
							| 1 |  | swrdcl | ⊢ ( 𝑆  ∈  Word  𝐴  →  ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ∈  Word  𝐴 ) | 
						
							| 2 | 1 | adantr | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ∈  Word  𝐴 ) | 
						
							| 3 |  | swrdcl | ⊢ ( 𝑆  ∈  Word  𝐴  →  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 )  ∈  Word  𝐴 ) | 
						
							| 4 | 3 | adantr | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 )  ∈  Word  𝐴 ) | 
						
							| 5 |  | ccatcl | ⊢ ( ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ∈  Word  𝐴  ∧  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 )  ∈  Word  𝐴 )  →  ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ++  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) )  ∈  Word  𝐴 ) | 
						
							| 6 | 2 4 5 | syl2anc | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ++  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) )  ∈  Word  𝐴 ) | 
						
							| 7 |  | wrdfn | ⊢ ( ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ++  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) )  ∈  Word  𝐴  →  ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ++  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) )  Fn  ( 0 ..^ ( ♯ ‘ ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ++  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ) ) ) ) | 
						
							| 8 | 6 7 | syl | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ++  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) )  Fn  ( 0 ..^ ( ♯ ‘ ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ++  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ) ) ) ) | 
						
							| 9 |  | ccatlen | ⊢ ( ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ∈  Word  𝐴  ∧  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 )  ∈  Word  𝐴 )  →  ( ♯ ‘ ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ++  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ) )  =  ( ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) )  +  ( ♯ ‘ ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ) ) ) | 
						
							| 10 | 2 4 9 | syl2anc | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( ♯ ‘ ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ++  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ) )  =  ( ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) )  +  ( ♯ ‘ ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ) ) ) | 
						
							| 11 |  | simpl | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  𝑆  ∈  Word  𝐴 ) | 
						
							| 12 |  | simpr1 | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  𝑋  ∈  ( 0 ... 𝑌 ) ) | 
						
							| 13 |  | simpr2 | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  𝑌  ∈  ( 0 ... 𝑍 ) ) | 
						
							| 14 |  | simpr3 | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) | 
						
							| 15 |  | fzass4 | ⊢ ( ( 𝑌  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) )  ∧  𝑍  ∈  ( 𝑌 ... ( ♯ ‘ 𝑆 ) ) )  ↔  ( 𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) ) | 
						
							| 16 | 15 | biimpri | ⊢ ( ( 𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) )  →  ( 𝑌  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) )  ∧  𝑍  ∈  ( 𝑌 ... ( ♯ ‘ 𝑆 ) ) ) ) | 
						
							| 17 | 16 | simpld | ⊢ ( ( 𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) )  →  𝑌  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) | 
						
							| 18 | 13 14 17 | syl2anc | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  𝑌  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) | 
						
							| 19 |  | swrdlen | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) )  →  ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) )  =  ( 𝑌  −  𝑋 ) ) | 
						
							| 20 | 11 12 18 19 | syl3anc | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) )  =  ( 𝑌  −  𝑋 ) ) | 
						
							| 21 |  | swrdlen | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) )  →  ( ♯ ‘ ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) )  =  ( 𝑍  −  𝑌 ) ) | 
						
							| 22 | 21 | 3adant3r1 | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( ♯ ‘ ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) )  =  ( 𝑍  −  𝑌 ) ) | 
						
							| 23 | 20 22 | oveq12d | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) )  +  ( ♯ ‘ ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ) )  =  ( ( 𝑌  −  𝑋 )  +  ( 𝑍  −  𝑌 ) ) ) | 
						
							| 24 | 13 | elfzelzd | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  𝑌  ∈  ℤ ) | 
						
							| 25 | 24 | zcnd | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  𝑌  ∈  ℂ ) | 
						
							| 26 | 12 | elfzelzd | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  𝑋  ∈  ℤ ) | 
						
							| 27 | 26 | zcnd | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  𝑋  ∈  ℂ ) | 
						
							| 28 | 14 | elfzelzd | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  𝑍  ∈  ℤ ) | 
						
							| 29 | 28 | zcnd | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  𝑍  ∈  ℂ ) | 
						
							| 30 | 25 27 29 | npncan3d | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( ( 𝑌  −  𝑋 )  +  ( 𝑍  −  𝑌 ) )  =  ( 𝑍  −  𝑋 ) ) | 
						
							| 31 | 10 23 30 | 3eqtrd | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( ♯ ‘ ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ++  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ) )  =  ( 𝑍  −  𝑋 ) ) | 
						
							| 32 | 31 | oveq2d | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( 0 ..^ ( ♯ ‘ ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ++  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ) ) )  =  ( 0 ..^ ( 𝑍  −  𝑋 ) ) ) | 
						
							| 33 | 32 | fneq2d | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ++  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) )  Fn  ( 0 ..^ ( ♯ ‘ ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ++  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ) ) )  ↔  ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ++  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) )  Fn  ( 0 ..^ ( 𝑍  −  𝑋 ) ) ) ) | 
						
							| 34 | 8 33 | mpbid | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ++  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) )  Fn  ( 0 ..^ ( 𝑍  −  𝑋 ) ) ) | 
						
							| 35 |  | swrdcl | ⊢ ( 𝑆  ∈  Word  𝐴  →  ( 𝑆  substr  〈 𝑋 ,  𝑍 〉 )  ∈  Word  𝐴 ) | 
						
							| 36 | 35 | adantr | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( 𝑆  substr  〈 𝑋 ,  𝑍 〉 )  ∈  Word  𝐴 ) | 
						
							| 37 |  | wrdfn | ⊢ ( ( 𝑆  substr  〈 𝑋 ,  𝑍 〉 )  ∈  Word  𝐴  →  ( 𝑆  substr  〈 𝑋 ,  𝑍 〉 )  Fn  ( 0 ..^ ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑍 〉 ) ) ) ) | 
						
							| 38 | 36 37 | syl | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( 𝑆  substr  〈 𝑋 ,  𝑍 〉 )  Fn  ( 0 ..^ ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑍 〉 ) ) ) ) | 
						
							| 39 |  | fzass4 | ⊢ ( ( 𝑋  ∈  ( 0 ... 𝑍 )  ∧  𝑌  ∈  ( 𝑋 ... 𝑍 ) )  ↔  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 ) ) ) | 
						
							| 40 | 39 | biimpri | ⊢ ( ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 ) )  →  ( 𝑋  ∈  ( 0 ... 𝑍 )  ∧  𝑌  ∈  ( 𝑋 ... 𝑍 ) ) ) | 
						
							| 41 | 40 | simpld | ⊢ ( ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 ) )  →  𝑋  ∈  ( 0 ... 𝑍 ) ) | 
						
							| 42 | 12 13 41 | syl2anc | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  𝑋  ∈  ( 0 ... 𝑍 ) ) | 
						
							| 43 |  | swrdlen | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  𝑋  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) )  →  ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑍 〉 ) )  =  ( 𝑍  −  𝑋 ) ) | 
						
							| 44 | 11 42 14 43 | syl3anc | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑍 〉 ) )  =  ( 𝑍  −  𝑋 ) ) | 
						
							| 45 | 44 | oveq2d | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( 0 ..^ ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑍 〉 ) ) )  =  ( 0 ..^ ( 𝑍  −  𝑋 ) ) ) | 
						
							| 46 | 45 | fneq2d | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( ( 𝑆  substr  〈 𝑋 ,  𝑍 〉 )  Fn  ( 0 ..^ ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑍 〉 ) ) )  ↔  ( 𝑆  substr  〈 𝑋 ,  𝑍 〉 )  Fn  ( 0 ..^ ( 𝑍  −  𝑋 ) ) ) ) | 
						
							| 47 | 38 46 | mpbid | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( 𝑆  substr  〈 𝑋 ,  𝑍 〉 )  Fn  ( 0 ..^ ( 𝑍  −  𝑋 ) ) ) | 
						
							| 48 | 24 26 | zsubcld | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( 𝑌  −  𝑋 )  ∈  ℤ ) | 
						
							| 49 | 48 | anim1ci | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( 0 ..^ ( 𝑍  −  𝑋 ) ) )  →  ( 𝑥  ∈  ( 0 ..^ ( 𝑍  −  𝑋 ) )  ∧  ( 𝑌  −  𝑋 )  ∈  ℤ ) ) | 
						
							| 50 |  | fzospliti | ⊢ ( ( 𝑥  ∈  ( 0 ..^ ( 𝑍  −  𝑋 ) )  ∧  ( 𝑌  −  𝑋 )  ∈  ℤ )  →  ( 𝑥  ∈  ( 0 ..^ ( 𝑌  −  𝑋 ) )  ∨  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) ) ) | 
						
							| 51 | 49 50 | syl | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( 0 ..^ ( 𝑍  −  𝑋 ) ) )  →  ( 𝑥  ∈  ( 0 ..^ ( 𝑌  −  𝑋 ) )  ∨  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) ) ) | 
						
							| 52 | 1 | ad2antrr | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( 0 ..^ ( 𝑌  −  𝑋 ) ) )  →  ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ∈  Word  𝐴 ) | 
						
							| 53 | 3 | ad2antrr | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( 0 ..^ ( 𝑌  −  𝑋 ) ) )  →  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 )  ∈  Word  𝐴 ) | 
						
							| 54 | 20 | oveq2d | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( 0 ..^ ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ) )  =  ( 0 ..^ ( 𝑌  −  𝑋 ) ) ) | 
						
							| 55 | 54 | eleq2d | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( 𝑥  ∈  ( 0 ..^ ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ) )  ↔  𝑥  ∈  ( 0 ..^ ( 𝑌  −  𝑋 ) ) ) ) | 
						
							| 56 | 55 | biimpar | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( 0 ..^ ( 𝑌  −  𝑋 ) ) )  →  𝑥  ∈  ( 0 ..^ ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ) ) ) | 
						
							| 57 |  | ccatval1 | ⊢ ( ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ∈  Word  𝐴  ∧  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 )  ∈  Word  𝐴  ∧  𝑥  ∈  ( 0 ..^ ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ) ) )  →  ( ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ++  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ) ‘ 𝑥 )  =  ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ‘ 𝑥 ) ) | 
						
							| 58 | 52 53 56 57 | syl3anc | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( 0 ..^ ( 𝑌  −  𝑋 ) ) )  →  ( ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ++  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ) ‘ 𝑥 )  =  ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ‘ 𝑥 ) ) | 
						
							| 59 |  | simpll | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( 0 ..^ ( 𝑌  −  𝑋 ) ) )  →  𝑆  ∈  Word  𝐴 ) | 
						
							| 60 |  | simplr1 | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( 0 ..^ ( 𝑌  −  𝑋 ) ) )  →  𝑋  ∈  ( 0 ... 𝑌 ) ) | 
						
							| 61 | 18 | adantr | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( 0 ..^ ( 𝑌  −  𝑋 ) ) )  →  𝑌  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) | 
						
							| 62 |  | simpr | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( 0 ..^ ( 𝑌  −  𝑋 ) ) )  →  𝑥  ∈  ( 0 ..^ ( 𝑌  −  𝑋 ) ) ) | 
						
							| 63 |  | swrdfv | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) )  ∧  𝑥  ∈  ( 0 ..^ ( 𝑌  −  𝑋 ) ) )  →  ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ‘ 𝑥 )  =  ( 𝑆 ‘ ( 𝑥  +  𝑋 ) ) ) | 
						
							| 64 | 59 60 61 62 63 | syl31anc | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( 0 ..^ ( 𝑌  −  𝑋 ) ) )  →  ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ‘ 𝑥 )  =  ( 𝑆 ‘ ( 𝑥  +  𝑋 ) ) ) | 
						
							| 65 | 58 64 | eqtrd | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( 0 ..^ ( 𝑌  −  𝑋 ) ) )  →  ( ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ++  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ) ‘ 𝑥 )  =  ( 𝑆 ‘ ( 𝑥  +  𝑋 ) ) ) | 
						
							| 66 | 1 | ad2antrr | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) )  →  ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ∈  Word  𝐴 ) | 
						
							| 67 | 3 | ad2antrr | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) )  →  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 )  ∈  Word  𝐴 ) | 
						
							| 68 | 23 30 | eqtrd | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) )  +  ( ♯ ‘ ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ) )  =  ( 𝑍  −  𝑋 ) ) | 
						
							| 69 | 20 68 | oveq12d | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ) ..^ ( ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) )  +  ( ♯ ‘ ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ) ) )  =  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) ) | 
						
							| 70 | 69 | eleq2d | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( 𝑥  ∈  ( ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ) ..^ ( ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) )  +  ( ♯ ‘ ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ) ) )  ↔  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) ) ) | 
						
							| 71 | 70 | biimpar | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) )  →  𝑥  ∈  ( ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ) ..^ ( ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) )  +  ( ♯ ‘ ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ) ) ) ) | 
						
							| 72 |  | ccatval2 | ⊢ ( ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ∈  Word  𝐴  ∧  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 )  ∈  Word  𝐴  ∧  𝑥  ∈  ( ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ) ..^ ( ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) )  +  ( ♯ ‘ ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ) ) ) )  →  ( ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ++  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ) ‘ 𝑥 )  =  ( ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ‘ ( 𝑥  −  ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ) ) ) ) | 
						
							| 73 | 66 67 71 72 | syl3anc | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) )  →  ( ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ++  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ) ‘ 𝑥 )  =  ( ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ‘ ( 𝑥  −  ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ) ) ) ) | 
						
							| 74 |  | simpll | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) )  →  𝑆  ∈  Word  𝐴 ) | 
						
							| 75 |  | simplr2 | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) )  →  𝑌  ∈  ( 0 ... 𝑍 ) ) | 
						
							| 76 |  | simplr3 | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) )  →  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) | 
						
							| 77 | 20 | oveq2d | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( 𝑥  −  ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ) )  =  ( 𝑥  −  ( 𝑌  −  𝑋 ) ) ) | 
						
							| 78 | 77 | adantr | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) )  →  ( 𝑥  −  ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ) )  =  ( 𝑥  −  ( 𝑌  −  𝑋 ) ) ) | 
						
							| 79 | 30 | oveq2d | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( ( 𝑌  −  𝑋 ) ..^ ( ( 𝑌  −  𝑋 )  +  ( 𝑍  −  𝑌 ) ) )  =  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) ) | 
						
							| 80 | 79 | eleq2d | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( 𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( ( 𝑌  −  𝑋 )  +  ( 𝑍  −  𝑌 ) ) )  ↔  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) ) ) | 
						
							| 81 | 80 | biimpar | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) )  →  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( ( 𝑌  −  𝑋 )  +  ( 𝑍  −  𝑌 ) ) ) ) | 
						
							| 82 | 28 24 | zsubcld | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( 𝑍  −  𝑌 )  ∈  ℤ ) | 
						
							| 83 | 82 | adantr | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) )  →  ( 𝑍  −  𝑌 )  ∈  ℤ ) | 
						
							| 84 |  | fzosubel3 | ⊢ ( ( 𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( ( 𝑌  −  𝑋 )  +  ( 𝑍  −  𝑌 ) ) )  ∧  ( 𝑍  −  𝑌 )  ∈  ℤ )  →  ( 𝑥  −  ( 𝑌  −  𝑋 ) )  ∈  ( 0 ..^ ( 𝑍  −  𝑌 ) ) ) | 
						
							| 85 | 81 83 84 | syl2anc | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) )  →  ( 𝑥  −  ( 𝑌  −  𝑋 ) )  ∈  ( 0 ..^ ( 𝑍  −  𝑌 ) ) ) | 
						
							| 86 | 78 85 | eqeltrd | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) )  →  ( 𝑥  −  ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ) )  ∈  ( 0 ..^ ( 𝑍  −  𝑌 ) ) ) | 
						
							| 87 |  | swrdfv | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) )  ∧  ( 𝑥  −  ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ) )  ∈  ( 0 ..^ ( 𝑍  −  𝑌 ) ) )  →  ( ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ‘ ( 𝑥  −  ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ) ) )  =  ( 𝑆 ‘ ( ( 𝑥  −  ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ) )  +  𝑌 ) ) ) | 
						
							| 88 | 74 75 76 86 87 | syl31anc | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) )  →  ( ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ‘ ( 𝑥  −  ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ) ) )  =  ( 𝑆 ‘ ( ( 𝑥  −  ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ) )  +  𝑌 ) ) ) | 
						
							| 89 | 77 | oveq1d | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( ( 𝑥  −  ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ) )  +  𝑌 )  =  ( ( 𝑥  −  ( 𝑌  −  𝑋 ) )  +  𝑌 ) ) | 
						
							| 90 | 89 | adantr | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) )  →  ( ( 𝑥  −  ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ) )  +  𝑌 )  =  ( ( 𝑥  −  ( 𝑌  −  𝑋 ) )  +  𝑌 ) ) | 
						
							| 91 |  | elfzoelz | ⊢ ( 𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) )  →  𝑥  ∈  ℤ ) | 
						
							| 92 | 91 | zcnd | ⊢ ( 𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) )  →  𝑥  ∈  ℂ ) | 
						
							| 93 | 92 | adantl | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) )  →  𝑥  ∈  ℂ ) | 
						
							| 94 | 25 27 | subcld | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( 𝑌  −  𝑋 )  ∈  ℂ ) | 
						
							| 95 | 94 | adantr | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) )  →  ( 𝑌  −  𝑋 )  ∈  ℂ ) | 
						
							| 96 | 25 | adantr | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) )  →  𝑌  ∈  ℂ ) | 
						
							| 97 | 93 95 96 | subadd23d | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) )  →  ( ( 𝑥  −  ( 𝑌  −  𝑋 ) )  +  𝑌 )  =  ( 𝑥  +  ( 𝑌  −  ( 𝑌  −  𝑋 ) ) ) ) | 
						
							| 98 | 25 27 | nncand | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( 𝑌  −  ( 𝑌  −  𝑋 ) )  =  𝑋 ) | 
						
							| 99 | 98 | oveq2d | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( 𝑥  +  ( 𝑌  −  ( 𝑌  −  𝑋 ) ) )  =  ( 𝑥  +  𝑋 ) ) | 
						
							| 100 | 99 | adantr | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) )  →  ( 𝑥  +  ( 𝑌  −  ( 𝑌  −  𝑋 ) ) )  =  ( 𝑥  +  𝑋 ) ) | 
						
							| 101 | 90 97 100 | 3eqtrd | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) )  →  ( ( 𝑥  −  ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ) )  +  𝑌 )  =  ( 𝑥  +  𝑋 ) ) | 
						
							| 102 | 101 | fveq2d | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) )  →  ( 𝑆 ‘ ( ( 𝑥  −  ( ♯ ‘ ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 ) ) )  +  𝑌 ) )  =  ( 𝑆 ‘ ( 𝑥  +  𝑋 ) ) ) | 
						
							| 103 | 73 88 102 | 3eqtrd | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) )  →  ( ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ++  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ) ‘ 𝑥 )  =  ( 𝑆 ‘ ( 𝑥  +  𝑋 ) ) ) | 
						
							| 104 | 65 103 | jaodan | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  ( 𝑥  ∈  ( 0 ..^ ( 𝑌  −  𝑋 ) )  ∨  𝑥  ∈  ( ( 𝑌  −  𝑋 ) ..^ ( 𝑍  −  𝑋 ) ) ) )  →  ( ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ++  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ) ‘ 𝑥 )  =  ( 𝑆 ‘ ( 𝑥  +  𝑋 ) ) ) | 
						
							| 105 | 51 104 | syldan | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( 0 ..^ ( 𝑍  −  𝑋 ) ) )  →  ( ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ++  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ) ‘ 𝑥 )  =  ( 𝑆 ‘ ( 𝑥  +  𝑋 ) ) ) | 
						
							| 106 |  | simpll | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( 0 ..^ ( 𝑍  −  𝑋 ) ) )  →  𝑆  ∈  Word  𝐴 ) | 
						
							| 107 | 42 | adantr | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( 0 ..^ ( 𝑍  −  𝑋 ) ) )  →  𝑋  ∈  ( 0 ... 𝑍 ) ) | 
						
							| 108 |  | simplr3 | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( 0 ..^ ( 𝑍  −  𝑋 ) ) )  →  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) | 
						
							| 109 |  | simpr | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( 0 ..^ ( 𝑍  −  𝑋 ) ) )  →  𝑥  ∈  ( 0 ..^ ( 𝑍  −  𝑋 ) ) ) | 
						
							| 110 |  | swrdfv | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  𝑋  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) )  ∧  𝑥  ∈  ( 0 ..^ ( 𝑍  −  𝑋 ) ) )  →  ( ( 𝑆  substr  〈 𝑋 ,  𝑍 〉 ) ‘ 𝑥 )  =  ( 𝑆 ‘ ( 𝑥  +  𝑋 ) ) ) | 
						
							| 111 | 106 107 108 109 110 | syl31anc | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( 0 ..^ ( 𝑍  −  𝑋 ) ) )  →  ( ( 𝑆  substr  〈 𝑋 ,  𝑍 〉 ) ‘ 𝑥 )  =  ( 𝑆 ‘ ( 𝑥  +  𝑋 ) ) ) | 
						
							| 112 | 105 111 | eqtr4d | ⊢ ( ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  ∧  𝑥  ∈  ( 0 ..^ ( 𝑍  −  𝑋 ) ) )  →  ( ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ++  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) ) ‘ 𝑥 )  =  ( ( 𝑆  substr  〈 𝑋 ,  𝑍 〉 ) ‘ 𝑥 ) ) | 
						
							| 113 | 34 47 112 | eqfnfvd | ⊢ ( ( 𝑆  ∈  Word  𝐴  ∧  ( 𝑋  ∈  ( 0 ... 𝑌 )  ∧  𝑌  ∈  ( 0 ... 𝑍 )  ∧  𝑍  ∈  ( 0 ... ( ♯ ‘ 𝑆 ) ) ) )  →  ( ( 𝑆  substr  〈 𝑋 ,  𝑌 〉 )  ++  ( 𝑆  substr  〈 𝑌 ,  𝑍 〉 ) )  =  ( 𝑆  substr  〈 𝑋 ,  𝑍 〉 ) ) |