pfx2 - Metamath Proof Explorer

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Theorem pfx2 14900

Description: A prefix of length two. (Contributed by AV, 15-May-2020.)

**Assertion**
Ref	Expression
pfx2	⊢ ((𝑊 ∈ Word 𝑉 ∧ 2 ≤ (♯‘𝑊)) → (𝑊 prefix 2) = ⟨“(𝑊‘0)(𝑊‘1)”⟩)

Proof of Theorem pfx2 Dummy variable 𝑖 is distinct from all other variables.

Step	Hyp	Ref	Expression
1		2nn0 12445	. . . 4 ⊢ 2 ∈ ℕ₀
2	1	a1i 11	. . 3 ⊢ ((𝑊 ∈ Word 𝑉 ∧ 2 ≤ (♯‘𝑊)) → 2 ∈ ℕ₀)
3		lencl 14486	. . . 4 ⊢ (𝑊 ∈ Word 𝑉 → (♯‘𝑊) ∈ ℕ₀)
4	3	adantr 481	. . 3 ⊢ ((𝑊 ∈ Word 𝑉 ∧ 2 ≤ (♯‘𝑊)) → (♯‘𝑊) ∈ ℕ₀)
5		simpr 485	. . 3 ⊢ ((𝑊 ∈ Word 𝑉 ∧ 2 ≤ (♯‘𝑊)) → 2 ≤ (♯‘𝑊))
6		elfz2nn0 13563	. . 3 ⊢ (2 ∈ (0...(♯‘𝑊)) ↔ (2 ∈ ℕ₀ ∧ (♯‘𝑊) ∈ ℕ₀ ∧ 2 ≤ (♯‘𝑊)))
7	2, 4, 5, 6	syl3anbrc 1350	. 2 ⊢ ((𝑊 ∈ Word 𝑉 ∧ 2 ≤ (♯‘𝑊)) → 2 ∈ (0...(♯‘𝑊)))
8		pfxlen 14637	. . . 4 ⊢ ((𝑊 ∈ Word 𝑉 ∧ 2 ∈ (0...(♯‘𝑊))) → (♯‘(𝑊 prefix 2)) = 2)
9		s2len 14842	. . . . . . 7 ⊢ (♯‘⟨“(𝑊‘0)(𝑊‘1)”⟩) = 2
10	9	eqcomi 2748	. . . . . 6 ⊢ 2 = (♯‘⟨“(𝑊‘0)(𝑊‘1)”⟩)
11	10	a1i 11	. . . . 5 ⊢ (((𝑊 ∈ Word 𝑉 ∧ 2 ∈ (0...(♯‘𝑊))) ∧ (♯‘(𝑊 prefix 2)) = 2) → 2 = (♯‘⟨“(𝑊‘0)(𝑊‘1)”⟩))
12		2nn 12245	. . . . . . . . . 10 ⊢ 2 ∈ ℕ
13		lbfzo0 13645	. . . . . . . . . 10 ⊢ (0 ∈ (0..^2) ↔ 2 ∈ ℕ)
14	12, 13	mpbir 232	. . . . . . . . 9 ⊢ 0 ∈ (0..^2)
15		pfxfv 14636	. . . . . . . . 9 ⊢ ((𝑊 ∈ Word 𝑉 ∧ 2 ∈ (0...(♯‘𝑊)) ∧ 0 ∈ (0..^2)) → ((𝑊 prefix 2)‘0) = (𝑊‘0))
16	14, 15	mp3an3 1458	. . . . . . . 8 ⊢ ((𝑊 ∈ Word 𝑉 ∧ 2 ∈ (0...(♯‘𝑊))) → ((𝑊 prefix 2)‘0) = (𝑊‘0))
17	16	adantr 481	. . . . . . 7 ⊢ (((𝑊 ∈ Word 𝑉 ∧ 2 ∈ (0...(♯‘𝑊))) ∧ (♯‘(𝑊 prefix 2)) = 2) → ((𝑊 prefix 2)‘0) = (𝑊‘0))
18		fvex 6840	. . . . . . . 8 ⊢ (𝑊‘0) ∈ V
19		s2fv0 14840	. . . . . . . 8 ⊢ ((𝑊‘0) ∈ V → (⟨“(𝑊‘0)(𝑊‘1)”⟩‘0) = (𝑊‘0))
20	18, 19	ax-mp 5	. . . . . . 7 ⊢ (⟨“(𝑊‘0)(𝑊‘1)”⟩‘0) = (𝑊‘0)
21	17, 20	eqtr4di 2792	. . . . . 6 ⊢ (((𝑊 ∈ Word 𝑉 ∧ 2 ∈ (0...(♯‘𝑊))) ∧ (♯‘(𝑊 prefix 2)) = 2) → ((𝑊 prefix 2)‘0) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘0))
22		1nn0 12444	. . . . . . . . . 10 ⊢ 1 ∈ ℕ₀
23		1lt2 12338	. . . . . . . . . 10 ⊢ 1 < 2
24		elfzo0 13646	. . . . . . . . . 10 ⊢ (1 ∈ (0..^2) ↔ (1 ∈ ℕ₀ ∧ 2 ∈ ℕ ∧ 1 < 2))
25	22, 12, 23, 24	mpbir3an 1348	. . . . . . . . 9 ⊢ 1 ∈ (0..^2)
26		pfxfv 14636	. . . . . . . . 9 ⊢ ((𝑊 ∈ Word 𝑉 ∧ 2 ∈ (0...(♯‘𝑊)) ∧ 1 ∈ (0..^2)) → ((𝑊 prefix 2)‘1) = (𝑊‘1))
27	25, 26	mp3an3 1458	. . . . . . . 8 ⊢ ((𝑊 ∈ Word 𝑉 ∧ 2 ∈ (0...(♯‘𝑊))) → ((𝑊 prefix 2)‘1) = (𝑊‘1))
28		fvex 6840	. . . . . . . . 9 ⊢ (𝑊‘1) ∈ V
29		s2fv1 14841	. . . . . . . . 9 ⊢ ((𝑊‘1) ∈ V → (⟨“(𝑊‘0)(𝑊‘1)”⟩‘1) = (𝑊‘1))
30	28, 29	ax-mp 5	. . . . . . . 8 ⊢ (⟨“(𝑊‘0)(𝑊‘1)”⟩‘1) = (𝑊‘1)
31	27, 30	eqtr4di 2792	. . . . . . 7 ⊢ ((𝑊 ∈ Word 𝑉 ∧ 2 ∈ (0...(♯‘𝑊))) → ((𝑊 prefix 2)‘1) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘1))
32	31	adantr 481	. . . . . 6 ⊢ (((𝑊 ∈ Word 𝑉 ∧ 2 ∈ (0...(♯‘𝑊))) ∧ (♯‘(𝑊 prefix 2)) = 2) → ((𝑊 prefix 2)‘1) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘1))
33		0nn0 12443	. . . . . . 7 ⊢ 0 ∈ ℕ₀
34		fveq2 6827	. . . . . . . . 9 ⊢ (𝑖 = 0 → ((𝑊 prefix 2)‘𝑖) = ((𝑊 prefix 2)‘0))
35		fveq2 6827	. . . . . . . . 9 ⊢ (𝑖 = 0 → (⟨“(𝑊‘0)(𝑊‘1)”⟩‘𝑖) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘0))
36	34, 35	eqeq12d 2755	. . . . . . . 8 ⊢ (𝑖 = 0 → (((𝑊 prefix 2)‘𝑖) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘𝑖) ↔ ((𝑊 prefix 2)‘0) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘0)))
37		fveq2 6827	. . . . . . . . 9 ⊢ (𝑖 = 1 → ((𝑊 prefix 2)‘𝑖) = ((𝑊 prefix 2)‘1))
38		fveq2 6827	. . . . . . . . 9 ⊢ (𝑖 = 1 → (⟨“(𝑊‘0)(𝑊‘1)”⟩‘𝑖) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘1))
39	37, 38	eqeq12d 2755	. . . . . . . 8 ⊢ (𝑖 = 1 → (((𝑊 prefix 2)‘𝑖) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘𝑖) ↔ ((𝑊 prefix 2)‘1) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘1)))
40	36, 39	ralprg 4628	. . . . . . 7 ⊢ ((0 ∈ ℕ₀ ∧ 1 ∈ ℕ₀) → (∀𝑖 ∈ {0, 1} ((𝑊 prefix 2)‘𝑖) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘𝑖) ↔ (((𝑊 prefix 2)‘0) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘0) ∧ ((𝑊 prefix 2)‘1) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘1))))
41	33, 22, 40	mp2an 698	. . . . . 6 ⊢ (∀𝑖 ∈ {0, 1} ((𝑊 prefix 2)‘𝑖) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘𝑖) ↔ (((𝑊 prefix 2)‘0) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘0) ∧ ((𝑊 prefix 2)‘1) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘1)))
42	21, 32, 41	sylanbrc 589	. . . . 5 ⊢ (((𝑊 ∈ Word 𝑉 ∧ 2 ∈ (0...(♯‘𝑊))) ∧ (♯‘(𝑊 prefix 2)) = 2) → ∀𝑖 ∈ {0, 1} ((𝑊 prefix 2)‘𝑖) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘𝑖))
43		eqeq1 2743	. . . . . . 7 ⊢ ((♯‘(𝑊 prefix 2)) = 2 → ((♯‘(𝑊 prefix 2)) = (♯‘⟨“(𝑊‘0)(𝑊‘1)”⟩) ↔ 2 = (♯‘⟨“(𝑊‘0)(𝑊‘1)”⟩)))
44		oveq2 7364	. . . . . . . . 9 ⊢ ((♯‘(𝑊 prefix 2)) = 2 → (0..^(♯‘(𝑊 prefix 2))) = (0..^2))
45		fzo0to2pr 13696	. . . . . . . . 9 ⊢ (0..^2) = {0, 1}
46	44, 45	eqtrdi 2790	. . . . . . . 8 ⊢ ((♯‘(𝑊 prefix 2)) = 2 → (0..^(♯‘(𝑊 prefix 2))) = {0, 1})
47	46	raleqdv 3297	. . . . . . 7 ⊢ ((♯‘(𝑊 prefix 2)) = 2 → (∀𝑖 ∈ (0..^(♯‘(𝑊 prefix 2)))((𝑊 prefix 2)‘𝑖) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘𝑖) ↔ ∀𝑖 ∈ {0, 1} ((𝑊 prefix 2)‘𝑖) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘𝑖)))
48	43, 47	anbi12d 638	. . . . . 6 ⊢ ((♯‘(𝑊 prefix 2)) = 2 → (((♯‘(𝑊 prefix 2)) = (♯‘⟨“(𝑊‘0)(𝑊‘1)”⟩) ∧ ∀𝑖 ∈ (0..^(♯‘(𝑊 prefix 2)))((𝑊 prefix 2)‘𝑖) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘𝑖)) ↔ (2 = (♯‘⟨“(𝑊‘0)(𝑊‘1)”⟩) ∧ ∀𝑖 ∈ {0, 1} ((𝑊 prefix 2)‘𝑖) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘𝑖))))
49	48	adantl 482	. . . . 5 ⊢ (((𝑊 ∈ Word 𝑉 ∧ 2 ∈ (0...(♯‘𝑊))) ∧ (♯‘(𝑊 prefix 2)) = 2) → (((♯‘(𝑊 prefix 2)) = (♯‘⟨“(𝑊‘0)(𝑊‘1)”⟩) ∧ ∀𝑖 ∈ (0..^(♯‘(𝑊 prefix 2)))((𝑊 prefix 2)‘𝑖) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘𝑖)) ↔ (2 = (♯‘⟨“(𝑊‘0)(𝑊‘1)”⟩) ∧ ∀𝑖 ∈ {0, 1} ((𝑊 prefix 2)‘𝑖) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘𝑖))))
50	11, 42, 49	mpbir2and 719	. . . 4 ⊢ (((𝑊 ∈ Word 𝑉 ∧ 2 ∈ (0...(♯‘𝑊))) ∧ (♯‘(𝑊 prefix 2)) = 2) → ((♯‘(𝑊 prefix 2)) = (♯‘⟨“(𝑊‘0)(𝑊‘1)”⟩) ∧ ∀𝑖 ∈ (0..^(♯‘(𝑊 prefix 2)))((𝑊 prefix 2)‘𝑖) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘𝑖)))
51	8, 50	mpdan 693	. . 3 ⊢ ((𝑊 ∈ Word 𝑉 ∧ 2 ∈ (0...(♯‘𝑊))) → ((♯‘(𝑊 prefix 2)) = (♯‘⟨“(𝑊‘0)(𝑊‘1)”⟩) ∧ ∀𝑖 ∈ (0..^(♯‘(𝑊 prefix 2)))((𝑊 prefix 2)‘𝑖) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘𝑖)))
52		pfxcl 14631	. . . . 5 ⊢ (𝑊 ∈ Word 𝑉 → (𝑊 prefix 2) ∈ Word 𝑉)
53		s2cli 14833	. . . . 5 ⊢ ⟨“(𝑊‘0)(𝑊‘1)”⟩ ∈ Word V
54		eqwrd 14510	. . . . 5 ⊢ (((𝑊 prefix 2) ∈ Word 𝑉 ∧ ⟨“(𝑊‘0)(𝑊‘1)”⟩ ∈ Word V) → ((𝑊 prefix 2) = ⟨“(𝑊‘0)(𝑊‘1)”⟩ ↔ ((♯‘(𝑊 prefix 2)) = (♯‘⟨“(𝑊‘0)(𝑊‘1)”⟩) ∧ ∀𝑖 ∈ (0..^(♯‘(𝑊 prefix 2)))((𝑊 prefix 2)‘𝑖) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘𝑖))))
55	52, 53, 54	sylancl 592	. . . 4 ⊢ (𝑊 ∈ Word 𝑉 → ((𝑊 prefix 2) = ⟨“(𝑊‘0)(𝑊‘1)”⟩ ↔ ((♯‘(𝑊 prefix 2)) = (♯‘⟨“(𝑊‘0)(𝑊‘1)”⟩) ∧ ∀𝑖 ∈ (0..^(♯‘(𝑊 prefix 2)))((𝑊 prefix 2)‘𝑖) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘𝑖))))
56	55	adantr 481	. . 3 ⊢ ((𝑊 ∈ Word 𝑉 ∧ 2 ∈ (0...(♯‘𝑊))) → ((𝑊 prefix 2) = ⟨“(𝑊‘0)(𝑊‘1)”⟩ ↔ ((♯‘(𝑊 prefix 2)) = (♯‘⟨“(𝑊‘0)(𝑊‘1)”⟩) ∧ ∀𝑖 ∈ (0..^(♯‘(𝑊 prefix 2)))((𝑊 prefix 2)‘𝑖) = (⟨“(𝑊‘0)(𝑊‘1)”⟩‘𝑖))))
57	51, 56	mpbird 258	. 2 ⊢ ((𝑊 ∈ Word 𝑉 ∧ 2 ∈ (0...(♯‘𝑊))) → (𝑊 prefix 2) = ⟨“(𝑊‘0)(𝑊‘1)”⟩)
58	7, 57	syldan 597	1 ⊢ ((𝑊 ∈ Word 𝑉 ∧ 2 ≤ (♯‘𝑊)) → (𝑊 prefix 2) = ⟨“(𝑊‘0)(𝑊‘1)”⟩)

Colors of variables: wff setvar class

Syntax hints: → wi 4 ↔ wb 207 ∧ wa 396 = wceq 1547 ∈ wcel 2119 ∀wral 3053 Vcvv 3431 {cpr 4557 class class class wbr 5072 ‘cfv 6485 (class class class)co 7356 0cc0 11029 1c1 11030 < clt 11170 ≤ cle 11171 ℕcn 12165 2c2 12227 ℕ₀cn0 12428 ...cfz 13452 ..^cfzo 13599 ♯chash 14283 Word cword 14466 prefix cpfx 14624 ⟨“cs2 14794

This theorem was proved from axioms: ax-mp 5 ax-1 6 ax-2 7 ax-3 8 ax-gen 1802 ax-4 1816 ax-5 1917 ax-6 1974 ax-7 2015 ax-8 2121 ax-9 2129 ax-10 2152 ax-11 2168 ax-12 2189 ax-ext 2711 ax-rep 5199 ax-sep 5218 ax-nul 5228 ax-pow 5294 ax-pr 5362 ax-un 7678 ax-cnex 11085 ax-resscn 11086 ax-1cn 11087 ax-icn 11088 ax-addcl 11089 ax-addrcl 11090 ax-mulcl 11091 ax-mulrcl 11092 ax-mulcom 11093 ax-addass 11094 ax-mulass 11095 ax-distr 11096 ax-i2m1 11097 ax-1ne0 11098 ax-1rid 11099 ax-rnegex 11100 ax-rrecex 11101 ax-cnre 11102 ax-pre-lttri 11103 ax-pre-lttrn 11104 ax-pre-ltadd 11105 ax-pre-mulgt0 11106

This theorem depends on definitions: df-bi 208 df-an 397 df-or 854 df-3or 1093 df-3an 1094 df-tru 1550 df-fal 1560 df-ex 1787 df-nf 1791 df-sb 2074 df-mo 2543 df-eu 2573 df-clab 2718 df-cleq 2731 df-clel 2814 df-nfc 2888 df-ne 2935 df-nel 3039 df-ral 3054 df-rex 3064 df-reu 3345 df-rab 3392 df-v 3433 df-sbc 3724 df-csb 3832 df-dif 3886 df-un 3888 df-in 3890 df-ss 3900 df-pss 3903 df-nul 4262 df-if 4455 df-pw 4531 df-sn 4556 df-pr 4558 df-op 4562 df-uni 4839 df-int 4878 df-iun 4923 df-br 5073 df-opab 5135 df-mpt 5154 df-tr 5180 df-id 5513 df-eprel 5518 df-po 5526 df-so 5527 df-fr 5571 df-we 5573 df-xp 5624 df-rel 5625 df-cnv 5626 df-co 5627 df-dm 5628 df-rn 5629 df-res 5630 df-ima 5631 df-pred 6252 df-ord 6313 df-on 6314 df-lim 6315 df-suc 6316 df-iota 6441 df-fun 6487 df-fn 6488 df-f 6489 df-f1 6490 df-fo 6491 df-f1o 6492 df-fv 6493 df-riota 7313 df-ov 7359 df-oprab 7360 df-mpo 7361 df-om 7807 df-1st 7931 df-2nd 7932 df-frecs 8221 df-wrecs 8252 df-recs 8301 df-rdg 8339 df-1o 8395 df-er 8633 df-en 8884 df-dom 8885 df-sdom 8886 df-fin 8887 df-card 9854 df-pnf 11172 df-mnf 11173 df-xr 11174 df-ltxr 11175 df-le 11176 df-sub 11370 df-neg 11371 df-nn 12166 df-2 12235 df-n0 12429 df-z 12516 df-uz 12780 df-fz 13453 df-fzo 13600 df-hash 14284 df-word 14467 df-concat 14524 df-s1 14550 df-substr 14595 df-pfx 14625 df-s2 14801

This theorem is referenced by: (None)

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