Definition df-lgs 15871

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 15870	. 2 class /L
2		va	. . 3 setvar 𝑎
3		vn	. . 3 setvar 𝑛
4		cz 9577	. . 3 class ℤ
5	3	cv 1397	. . . . 5 class 𝑛
6		cc0 8127	. . . . 5 class 0
7	5, 6	wceq 1398	. . . 4 wff 𝑛 = 0
8	2	cv 1397	. . . . . . 7 class 𝑎
9		c2 9288	. . . . . . 7 class 2
10		cexp 10900	. . . . . . 7 class ↑
11	8, 9, 10	co 6050	. . . . . 6 class (𝑎↑2)
12		c1 8128	. . . . . 6 class 1
13	11, 12	wceq 1398	. . . . 5 wff (𝑎↑2) = 1
14	13, 12, 6	cif 3620	. . . 4 class if((𝑎↑2) = 1, 1, 0)
15		clt 8308	. . . . . . . 8 class <
16	5, 6, 15	wbr 4109	. . . . . . 7 wff 𝑛 < 0
17	8, 6, 15	wbr 4109	. . . . . . 7 wff 𝑎 < 0
18	16, 17	wa 104	. . . . . 6 wff (𝑛 < 0 ∧ 𝑎 < 0)
19	12	cneg 8445	. . . . . 6 class -1
20	18, 19, 12	cif 3620	. . . . 5 class if((𝑛 < 0 ∧ 𝑎 < 0), -1, 1)
21		cabs 11682	. . . . . . 7 class abs
22	5, 21	cfv 5352	. . . . . 6 class (abs‘𝑛)
23		cmul 8132	. . . . . . 7 class ·
24		vm	. . . . . . . 8 setvar 𝑚
25		cn 9237	. . . . . . . 8 class ℕ
26	24	cv 1397	. . . . . . . . . 10 class 𝑚
27		cprime 12804	. . . . . . . . . 10 class ℙ
28	26, 27	wcel 2203	. . . . . . . . 9 wff 𝑚 ∈ ℙ
29	26, 9	wceq 1398	. . . . . . . . . . 11 wff 𝑚 = 2
30		cdvds 12473	. . . . . . . . . . . . 13 class ∥
31	9, 8, 30	wbr 4109	. . . . . . . . . . . 12 wff 2 ∥ 𝑎
32		c8 9294	. . . . . . . . . . . . . . 15 class 8
33		cmo 10684	. . . . . . . . . . . . . . 15 class mod
34	8, 32, 33	co 6050	. . . . . . . . . . . . . 14 class (𝑎 mod 8)
35		c7 9293	. . . . . . . . . . . . . . 15 class 7
36	12, 35	cpr 3690	. . . . . . . . . . . . . 14 class {1, 7}
37	34, 36	wcel 2203	. . . . . . . . . . . . 13 wff (𝑎 mod 8) ∈ {1, 7}
38	37, 12, 19	cif 3620	. . . . . . . . . . . 12 class if((𝑎 mod 8) ∈ {1, 7}, 1, -1)
39	31, 6, 38	cif 3620	. . . . . . . . . . 11 class if(2 ∥ 𝑎, 0, if((𝑎 mod 8) ∈ {1, 7}, 1, -1))
40		cmin 8444	. . . . . . . . . . . . . . . . 17 class −
41	26, 12, 40	co 6050	. . . . . . . . . . . . . . . 16 class (𝑚 − 1)
42		cdiv 8946	. . . . . . . . . . . . . . . 16 class /
43	41, 9, 42	co 6050	. . . . . . . . . . . . . . 15 class ((𝑚 − 1) / 2)
44	8, 43, 10	co 6050	. . . . . . . . . . . . . 14 class (𝑎↑((𝑚 − 1) / 2))
45		caddc 8130	. . . . . . . . . . . . . 14 class +
46	44, 12, 45	co 6050	. . . . . . . . . . . . 13 class ((𝑎↑((𝑚 − 1) / 2)) + 1)
47	46, 26, 33	co 6050	. . . . . . . . . . . 12 class (((𝑎↑((𝑚 − 1) / 2)) + 1) mod 𝑚)
48	47, 12, 40	co 6050	. . . . . . . . . . 11 class ((((𝑎↑((𝑚 − 1) / 2)) + 1) mod 𝑚) − 1)
49	29, 39, 48	cif 3620	. . . . . . . . . 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 12982	. . . . . . . . . . 11 class pCnt
51	26, 5, 50	co 6050	. . . . . . . . . 10 class (𝑚 pCnt 𝑛)
52	49, 51, 10	co 6050	. . . . . . . . 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 3620	. . . . . . . 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 4171	. . . . . . 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 10809	. . . . . 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 5352	. . . . 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 6050	. . . 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 3620	. . 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 6052	. 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 1398	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  15877