Definition df-lgs 15717

Description: Define the Legendre symbol (actually the Kronecker symbol, which extends the Legendre symbol to all integers, and also the Jacobi symbol, which restricts the Kronecker symbol to positive odd integers). See definition in [ApostolNT] p. 179 resp. definition in [ApostolNT] p. 188. (Contributed by Mario Carneiro, 4-Feb-2015.)

Assertion

Ref	Expression
df-lgs	⊢ /L = (𝑎 ∈ ℤ, 𝑛 ∈ ℤ ↦ if(𝑛 = 0, if((𝑎↑2) = 1, 1, 0), (if((𝑛 < 0 ∧ 𝑎 < 0), -1, 1) · (seq1( · , (𝑚 ∈ ℕ ↦ if(𝑚 ∈ ℙ, (if(𝑚 = 2, if(2 ∥ 𝑎, 0, if((𝑎 mod 8) ∈ {1, 7}, 1, -1)), ((((𝑎↑((𝑚 − 1) / 2)) + 1) mod 𝑚) − 1))↑(𝑚 pCnt 𝑛)), 1)))‘(abs‘𝑛)))))

Distinct variable group:   𝑚,𝑎,𝑛

Detailed syntax breakdown of Definition df-lgs

Step	Hyp	Ref	Expression
1		clgs 15716	. 2 class /L
2		va	. . 3 setvar 𝑎
3		vn	. . 3 setvar 𝑛
4		cz 9469	. . 3 class ℤ
5	3	cv 1394	. . . . 5 class 𝑛
6		cc0 8022	. . . . 5 class 0
7	5, 6	wceq 1395	. . . 4 wff 𝑛 = 0
8	2	cv 1394	. . . . . . 7 class 𝑎
9		c2 9184	. . . . . . 7 class 2
10		cexp 10790	. . . . . . 7 class ↑
11	8, 9, 10	co 6013	. . . . . 6 class (𝑎↑2)
12		c1 8023	. . . . . 6 class 1
13	11, 12	wceq 1395	. . . . 5 wff (𝑎↑2) = 1
14	13, 12, 6	cif 3603	. . . 4 class if((𝑎↑2) = 1, 1, 0)
15		clt 8204	. . . . . . . 8 class <
16	5, 6, 15	wbr 4086	. . . . . . 7 wff 𝑛 < 0
17	8, 6, 15	wbr 4086	. . . . . . 7 wff 𝑎 < 0
18	16, 17	wa 104	. . . . . 6 wff (𝑛 < 0 ∧ 𝑎 < 0)
19	12	cneg 8341	. . . . . 6 class -1
20	18, 19, 12	cif 3603	. . . . 5 class if((𝑛 < 0 ∧ 𝑎 < 0), -1, 1)
21		cabs 11548	. . . . . . 7 class abs
22	5, 21	cfv 5324	. . . . . 6 class (abs‘𝑛)
23		cmul 8027	. . . . . . 7 class ·
24		vm	. . . . . . . 8 setvar 𝑚
25		cn 9133	. . . . . . . 8 class ℕ
26	24	cv 1394	. . . . . . . . . 10 class 𝑚
27		cprime 12669	. . . . . . . . . 10 class ℙ
28	26, 27	wcel 2200	. . . . . . . . 9 wff 𝑚 ∈ ℙ
29	26, 9	wceq 1395	. . . . . . . . . . 11 wff 𝑚 = 2
30		cdvds 12338	. . . . . . . . . . . . 13 class ∥
31	9, 8, 30	wbr 4086	. . . . . . . . . . . 12 wff 2 ∥ 𝑎
32		c8 9190	. . . . . . . . . . . . . . 15 class 8
33		cmo 10574	. . . . . . . . . . . . . . 15 class mod
34	8, 32, 33	co 6013	. . . . . . . . . . . . . 14 class (𝑎 mod 8)
35		c7 9189	. . . . . . . . . . . . . . 15 class 7
36	12, 35	cpr 3668	. . . . . . . . . . . . . 14 class {1, 7}
37	34, 36	wcel 2200	. . . . . . . . . . . . 13 wff (𝑎 mod 8) ∈ {1, 7}
38	37, 12, 19	cif 3603	. . . . . . . . . . . 12 class if((𝑎 mod 8) ∈ {1, 7}, 1, -1)
39	31, 6, 38	cif 3603	. . . . . . . . . . 11 class if(2 ∥ 𝑎, 0, if((𝑎 mod 8) ∈ {1, 7}, 1, -1))
40		cmin 8340	. . . . . . . . . . . . . . . . 17 class −
41	26, 12, 40	co 6013	. . . . . . . . . . . . . . . 16 class (𝑚 − 1)
42		cdiv 8842	. . . . . . . . . . . . . . . 16 class /
43	41, 9, 42	co 6013	. . . . . . . . . . . . . . 15 class ((𝑚 − 1) / 2)
44	8, 43, 10	co 6013	. . . . . . . . . . . . . 14 class (𝑎↑((𝑚 − 1) / 2))
45		caddc 8025	. . . . . . . . . . . . . 14 class +
46	44, 12, 45	co 6013	. . . . . . . . . . . . 13 class ((𝑎↑((𝑚 − 1) / 2)) + 1)
47	46, 26, 33	co 6013	. . . . . . . . . . . 12 class (((𝑎↑((𝑚 − 1) / 2)) + 1) mod 𝑚)
48	47, 12, 40	co 6013	. . . . . . . . . . 11 class ((((𝑎↑((𝑚 − 1) / 2)) + 1) mod 𝑚) − 1)
49	29, 39, 48	cif 3603	. . . . . . . . . 10 class if(𝑚 = 2, if(2 ∥ 𝑎, 0, if((𝑎 mod 8) ∈ {1, 7}, 1, -1)), ((((𝑎↑((𝑚 − 1) / 2)) + 1) mod 𝑚) − 1))
50		cpc 12847	. . . . . . . . . . 11 class pCnt
51	26, 5, 50	co 6013	. . . . . . . . . 10 class (𝑚 pCnt 𝑛)
52	49, 51, 10	co 6013	. . . . . . . . 9 class (if(𝑚 = 2, if(2 ∥ 𝑎, 0, if((𝑎 mod 8) ∈ {1, 7}, 1, -1)), ((((𝑎↑((𝑚 − 1) / 2)) + 1) mod 𝑚) − 1))↑(𝑚 pCnt 𝑛))
53	28, 52, 12	cif 3603	. . . . . . . 8 class if(𝑚 ∈ ℙ, (if(𝑚 = 2, if(2 ∥ 𝑎, 0, if((𝑎 mod 8) ∈ {1, 7}, 1, -1)), ((((𝑎↑((𝑚 − 1) / 2)) + 1) mod 𝑚) − 1))↑(𝑚 pCnt 𝑛)), 1)
54	24, 25, 53	cmpt 4148	. . . . . . 7 class (𝑚 ∈ ℕ ↦ if(𝑚 ∈ ℙ, (if(𝑚 = 2, if(2 ∥ 𝑎, 0, if((𝑎 mod 8) ∈ {1, 7}, 1, -1)), ((((𝑎↑((𝑚 − 1) / 2)) + 1) mod 𝑚) − 1))↑(𝑚 pCnt 𝑛)), 1))
55	23, 54, 12	cseq 10699	. . . . . 6 class seq1( · , (𝑚 ∈ ℕ ↦ if(𝑚 ∈ ℙ, (if(𝑚 = 2, if(2 ∥ 𝑎, 0, if((𝑎 mod 8) ∈ {1, 7}, 1, -1)), ((((𝑎↑((𝑚 − 1) / 2)) + 1) mod 𝑚) − 1))↑(𝑚 pCnt 𝑛)), 1)))
56	22, 55	cfv 5324	. . . . 5 class (seq1( · , (𝑚 ∈ ℕ ↦ if(𝑚 ∈ ℙ, (if(𝑚 = 2, if(2 ∥ 𝑎, 0, if((𝑎 mod 8) ∈ {1, 7}, 1, -1)), ((((𝑎↑((𝑚 − 1) / 2)) + 1) mod 𝑚) − 1))↑(𝑚 pCnt 𝑛)), 1)))‘(abs‘𝑛))
57	20, 56, 23	co 6013	. . . 4 class (if((𝑛 < 0 ∧ 𝑎 < 0), -1, 1) · (seq1( · , (𝑚 ∈ ℕ ↦ if(𝑚 ∈ ℙ, (if(𝑚 = 2, if(2 ∥ 𝑎, 0, if((𝑎 mod 8) ∈ {1, 7}, 1, -1)), ((((𝑎↑((𝑚 − 1) / 2)) + 1) mod 𝑚) − 1))↑(𝑚 pCnt 𝑛)), 1)))‘(abs‘𝑛)))
58	7, 14, 57	cif 3603	. . 3 class if(𝑛 = 0, if((𝑎↑2) = 1, 1, 0), (if((𝑛 < 0 ∧ 𝑎 < 0), -1, 1) · (seq1( · , (𝑚 ∈ ℕ ↦ if(𝑚 ∈ ℙ, (if(𝑚 = 2, if(2 ∥ 𝑎, 0, if((𝑎 mod 8) ∈ {1, 7}, 1, -1)), ((((𝑎↑((𝑚 − 1) / 2)) + 1) mod 𝑚) − 1))↑(𝑚 pCnt 𝑛)), 1)))‘(abs‘𝑛))))
59	2, 3, 4, 4, 58	cmpo 6015	. 2 class (𝑎 ∈ ℤ, 𝑛 ∈ ℤ ↦ if(𝑛 = 0, if((𝑎↑2) = 1, 1, 0), (if((𝑛 < 0 ∧ 𝑎 < 0), -1, 1) · (seq1( · , (𝑚 ∈ ℕ ↦ if(𝑚 ∈ ℙ, (if(𝑚 = 2, if(2 ∥ 𝑎, 0, if((𝑎 mod 8) ∈ {1, 7}, 1, -1)), ((((𝑎↑((𝑚 − 1) / 2)) + 1) mod 𝑚) − 1))↑(𝑚 pCnt 𝑛)), 1)))‘(abs‘𝑛)))))
60	1, 59	wceq 1395	1 wff /L = (𝑎 ∈ ℤ, 𝑛 ∈ ℤ ↦ if(𝑛 = 0, if((𝑎↑2) = 1, 1, 0), (if((𝑛 < 0 ∧ 𝑎 < 0), -1, 1) · (seq1( · , (𝑚 ∈ ℕ ↦ if(𝑚 ∈ ℙ, (if(𝑚 = 2, if(2 ∥ 𝑎, 0, if((𝑎 mod 8) ∈ {1, 7}, 1, -1)), ((((𝑎↑((𝑚 − 1) / 2)) + 1) mod 𝑚) − 1))↑(𝑚 pCnt 𝑛)), 1)))‘(abs‘𝑛)))))

This definition is referenced by:  lgsval  15723