Theorem dvdsabseq 10930

Description: If two integers divide each other, they must be equal, up to a difference in sign. Theorem 1.1(j) in [ApostolNT] p. 14. (Contributed by Mario Carneiro, 30-May-2014.) (Revised by AV, 7-Aug-2021.)

Assertion

Ref	Expression
dvdsabseq	⊢ ((𝑀 ∥ 𝑁 ∧ 𝑁 ∥ 𝑀) → (abs‘𝑀) = (abs‘𝑁))

Proof of Theorem dvdsabseq

Step	Hyp	Ref	Expression
1		dvdszrcl 10883	. . 3 ⊢ (𝑀 ∥ 𝑁 → (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ))
2		simpr 108	. . . . . . 7 ⊢ ((𝑀 ∥ 𝑁 ∧ 𝑁 ∥ 𝑀) → 𝑁 ∥ 𝑀)
3		breq1 3840	. . . . . . . . 9 ⊢ (𝑁 = 0 → (𝑁 ∥ 𝑀 ↔ 0 ∥ 𝑀))
4		0dvds 10898	. . . . . . . . . . 11 ⊢ (𝑀 ∈ ℤ → (0 ∥ 𝑀 ↔ 𝑀 = 0))
5	4	adantr 270	. . . . . . . . . 10 ⊢ ((𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ) → (0 ∥ 𝑀 ↔ 𝑀 = 0))
6		zcn 8725	. . . . . . . . . . . . 13 ⊢ (𝑀 ∈ ℤ → 𝑀 ∈ ℂ)
7	6	abs00ad 10463	. . . . . . . . . . . 12 ⊢ (𝑀 ∈ ℤ → ((abs‘𝑀) = 0 ↔ 𝑀 = 0))
8	7	bicomd 139	. . . . . . . . . . 11 ⊢ (𝑀 ∈ ℤ → (𝑀 = 0 ↔ (abs‘𝑀) = 0))
9	8	adantr 270	. . . . . . . . . 10 ⊢ ((𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ) → (𝑀 = 0 ↔ (abs‘𝑀) = 0))
10	5, 9	bitrd 186	. . . . . . . . 9 ⊢ ((𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ) → (0 ∥ 𝑀 ↔ (abs‘𝑀) = 0))
11	3, 10	sylan9bb 450	. . . . . . . 8 ⊢ ((𝑁 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → (𝑁 ∥ 𝑀 ↔ (abs‘𝑀) = 0))
12		fveq2 5289	. . . . . . . . . . 11 ⊢ (𝑁 = 0 → (abs‘𝑁) = (abs‘0))
13		abs0 10456	. . . . . . . . . . 11 ⊢ (abs‘0) = 0
14	12, 13	syl6eq 2136	. . . . . . . . . 10 ⊢ (𝑁 = 0 → (abs‘𝑁) = 0)
15	14	adantr 270	. . . . . . . . 9 ⊢ ((𝑁 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → (abs‘𝑁) = 0)
16	15	eqeq2d 2099	. . . . . . . 8 ⊢ ((𝑁 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → ((abs‘𝑀) = (abs‘𝑁) ↔ (abs‘𝑀) = 0))
17	11, 16	bitr4d 189	. . . . . . 7 ⊢ ((𝑁 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → (𝑁 ∥ 𝑀 ↔ (abs‘𝑀) = (abs‘𝑁)))
18	2, 17	syl5ib 152	. . . . . 6 ⊢ ((𝑁 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → ((𝑀 ∥ 𝑁 ∧ 𝑁 ∥ 𝑀) → (abs‘𝑀) = (abs‘𝑁)))
19	18	expd 254	. . . . 5 ⊢ ((𝑁 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → (𝑀 ∥ 𝑁 → (𝑁 ∥ 𝑀 → (abs‘𝑀) = (abs‘𝑁))))
20	19	expcom 114	. . . 4 ⊢ ((𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ) → (𝑁 = 0 → (𝑀 ∥ 𝑁 → (𝑁 ∥ 𝑀 → (abs‘𝑀) = (abs‘𝑁)))))
21		simprl 498	. . . . . . 7 ⊢ ((¬ 𝑁 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → 𝑀 ∈ ℤ)
22		simpr 108	. . . . . . . 8 ⊢ ((𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ) → 𝑁 ∈ ℤ)
23	22	adantl 271	. . . . . . 7 ⊢ ((¬ 𝑁 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → 𝑁 ∈ ℤ)
24		neqne 2263	. . . . . . . 8 ⊢ (¬ 𝑁 = 0 → 𝑁 ≠ 0)
25	24	adantr 270	. . . . . . 7 ⊢ ((¬ 𝑁 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → 𝑁 ≠ 0)
26		dvdsleabs2 10929	. . . . . . 7 ⊢ ((𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ ∧ 𝑁 ≠ 0) → (𝑀 ∥ 𝑁 → (abs‘𝑀) ≤ (abs‘𝑁)))
27	21, 23, 25, 26	syl3anc 1174	. . . . . 6 ⊢ ((¬ 𝑁 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → (𝑀 ∥ 𝑁 → (abs‘𝑀) ≤ (abs‘𝑁)))
28		simpr 108	. . . . . . . . . . . . 13 ⊢ ((𝑁 ∥ 𝑀 ∧ 𝑀 ∥ 𝑁) → 𝑀 ∥ 𝑁)
29		breq1 3840	. . . . . . . . . . . . . . 15 ⊢ (𝑀 = 0 → (𝑀 ∥ 𝑁 ↔ 0 ∥ 𝑁))
30		0dvds 10898	. . . . . . . . . . . . . . . . 17 ⊢ (𝑁 ∈ ℤ → (0 ∥ 𝑁 ↔ 𝑁 = 0))
31		eqcom 2090	. . . . . . . . . . . . . . . . . 18 ⊢ ((abs‘𝑁) = 0 ↔ 0 = (abs‘𝑁))
32		zcn 8725	. . . . . . . . . . . . . . . . . . 19 ⊢ (𝑁 ∈ ℤ → 𝑁 ∈ ℂ)
33	32	abs00ad 10463	. . . . . . . . . . . . . . . . . 18 ⊢ (𝑁 ∈ ℤ → ((abs‘𝑁) = 0 ↔ 𝑁 = 0))
34	31, 33	syl5rbbr 193	. . . . . . . . . . . . . . . . 17 ⊢ (𝑁 ∈ ℤ → (𝑁 = 0 ↔ 0 = (abs‘𝑁)))
35	30, 34	bitrd 186	. . . . . . . . . . . . . . . 16 ⊢ (𝑁 ∈ ℤ → (0 ∥ 𝑁 ↔ 0 = (abs‘𝑁)))
36	35	adantl 271	. . . . . . . . . . . . . . 15 ⊢ ((𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ) → (0 ∥ 𝑁 ↔ 0 = (abs‘𝑁)))
37	29, 36	sylan9bb 450	. . . . . . . . . . . . . 14 ⊢ ((𝑀 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → (𝑀 ∥ 𝑁 ↔ 0 = (abs‘𝑁)))
38		fveq2 5289	. . . . . . . . . . . . . . . . 17 ⊢ (𝑀 = 0 → (abs‘𝑀) = (abs‘0))
39	38, 13	syl6eq 2136	. . . . . . . . . . . . . . . 16 ⊢ (𝑀 = 0 → (abs‘𝑀) = 0)
40	39	adantr 270	. . . . . . . . . . . . . . 15 ⊢ ((𝑀 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → (abs‘𝑀) = 0)
41	40	eqeq1d 2096	. . . . . . . . . . . . . 14 ⊢ ((𝑀 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → ((abs‘𝑀) = (abs‘𝑁) ↔ 0 = (abs‘𝑁)))
42	37, 41	bitr4d 189	. . . . . . . . . . . . 13 ⊢ ((𝑀 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → (𝑀 ∥ 𝑁 ↔ (abs‘𝑀) = (abs‘𝑁)))
43	28, 42	syl5ib 152	. . . . . . . . . . . 12 ⊢ ((𝑀 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → ((𝑁 ∥ 𝑀 ∧ 𝑀 ∥ 𝑁) → (abs‘𝑀) = (abs‘𝑁)))
44	43	a1dd 47	. . . . . . . . . . 11 ⊢ ((𝑀 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → ((𝑁 ∥ 𝑀 ∧ 𝑀 ∥ 𝑁) → ((abs‘𝑀) ≤ (abs‘𝑁) → (abs‘𝑀) = (abs‘𝑁))))
45	44	expcomd 1375	. . . . . . . . . 10 ⊢ ((𝑀 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → (𝑀 ∥ 𝑁 → (𝑁 ∥ 𝑀 → ((abs‘𝑀) ≤ (abs‘𝑁) → (abs‘𝑀) = (abs‘𝑁)))))
46	45	expcom 114	. . . . . . . . 9 ⊢ ((𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ) → (𝑀 = 0 → (𝑀 ∥ 𝑁 → (𝑁 ∥ 𝑀 → ((abs‘𝑀) ≤ (abs‘𝑁) → (abs‘𝑀) = (abs‘𝑁))))))
47	22	adantl 271	. . . . . . . . . . . . 13 ⊢ ((¬ 𝑀 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → 𝑁 ∈ ℤ)
48		simprl 498	. . . . . . . . . . . . 13 ⊢ ((¬ 𝑀 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → 𝑀 ∈ ℤ)
49		neqne 2263	. . . . . . . . . . . . . 14 ⊢ (¬ 𝑀 = 0 → 𝑀 ≠ 0)
50	49	adantr 270	. . . . . . . . . . . . 13 ⊢ ((¬ 𝑀 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → 𝑀 ≠ 0)
51		dvdsleabs2 10929	. . . . . . . . . . . . 13 ⊢ ((𝑁 ∈ ℤ ∧ 𝑀 ∈ ℤ ∧ 𝑀 ≠ 0) → (𝑁 ∥ 𝑀 → (abs‘𝑁) ≤ (abs‘𝑀)))
52	47, 48, 50, 51	syl3anc 1174	. . . . . . . . . . . 12 ⊢ ((¬ 𝑀 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → (𝑁 ∥ 𝑀 → (abs‘𝑁) ≤ (abs‘𝑀)))
53		eqcom 2090	. . . . . . . . . . . . . . . 16 ⊢ ((abs‘𝑀) = (abs‘𝑁) ↔ (abs‘𝑁) = (abs‘𝑀))
54	32	abscld 10579	. . . . . . . . . . . . . . . . 17 ⊢ (𝑁 ∈ ℤ → (abs‘𝑁) ∈ ℝ)
55	6	abscld 10579	. . . . . . . . . . . . . . . . 17 ⊢ (𝑀 ∈ ℤ → (abs‘𝑀) ∈ ℝ)
56		letri3 7545	. . . . . . . . . . . . . . . . 17 ⊢ (((abs‘𝑁) ∈ ℝ ∧ (abs‘𝑀) ∈ ℝ) → ((abs‘𝑁) = (abs‘𝑀) ↔ ((abs‘𝑁) ≤ (abs‘𝑀) ∧ (abs‘𝑀) ≤ (abs‘𝑁))))
57	54, 55, 56	syl2anr 284	. . . . . . . . . . . . . . . 16 ⊢ ((𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ) → ((abs‘𝑁) = (abs‘𝑀) ↔ ((abs‘𝑁) ≤ (abs‘𝑀) ∧ (abs‘𝑀) ≤ (abs‘𝑁))))
58	53, 57	syl5bb 190	. . . . . . . . . . . . . . 15 ⊢ ((𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ) → ((abs‘𝑀) = (abs‘𝑁) ↔ ((abs‘𝑁) ≤ (abs‘𝑀) ∧ (abs‘𝑀) ≤ (abs‘𝑁))))
59	58	biimprd 156	. . . . . . . . . . . . . 14 ⊢ ((𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ) → (((abs‘𝑁) ≤ (abs‘𝑀) ∧ (abs‘𝑀) ≤ (abs‘𝑁)) → (abs‘𝑀) = (abs‘𝑁)))
60	59	expd 254	. . . . . . . . . . . . 13 ⊢ ((𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ) → ((abs‘𝑁) ≤ (abs‘𝑀) → ((abs‘𝑀) ≤ (abs‘𝑁) → (abs‘𝑀) = (abs‘𝑁))))
61	60	adantl 271	. . . . . . . . . . . 12 ⊢ ((¬ 𝑀 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → ((abs‘𝑁) ≤ (abs‘𝑀) → ((abs‘𝑀) ≤ (abs‘𝑁) → (abs‘𝑀) = (abs‘𝑁))))
62	52, 61	syld 44	. . . . . . . . . . 11 ⊢ ((¬ 𝑀 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → (𝑁 ∥ 𝑀 → ((abs‘𝑀) ≤ (abs‘𝑁) → (abs‘𝑀) = (abs‘𝑁))))
63	62	a1d 22	. . . . . . . . . 10 ⊢ ((¬ 𝑀 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → (𝑀 ∥ 𝑁 → (𝑁 ∥ 𝑀 → ((abs‘𝑀) ≤ (abs‘𝑁) → (abs‘𝑀) = (abs‘𝑁)))))
64	63	expcom 114	. . . . . . . . 9 ⊢ ((𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ) → (¬ 𝑀 = 0 → (𝑀 ∥ 𝑁 → (𝑁 ∥ 𝑀 → ((abs‘𝑀) ≤ (abs‘𝑁) → (abs‘𝑀) = (abs‘𝑁))))))
65		0z 8731	. . . . . . . . . . . 12 ⊢ 0 ∈ ℤ
66		zdceq 8792	. . . . . . . . . . . 12 ⊢ ((𝑀 ∈ ℤ ∧ 0 ∈ ℤ) → DECID 𝑀 = 0)
67	65, 66	mpan2 416	. . . . . . . . . . 11 ⊢ (𝑀 ∈ ℤ → DECID 𝑀 = 0)
68		exmiddc 782	. . . . . . . . . . 11 ⊢ (DECID 𝑀 = 0 → (𝑀 = 0 ∨ ¬ 𝑀 = 0))
69	67, 68	syl 14	. . . . . . . . . 10 ⊢ (𝑀 ∈ ℤ → (𝑀 = 0 ∨ ¬ 𝑀 = 0))
70	69	adantr 270	. . . . . . . . 9 ⊢ ((𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ) → (𝑀 = 0 ∨ ¬ 𝑀 = 0))
71	46, 64, 70	mpjaod 673	. . . . . . . 8 ⊢ ((𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ) → (𝑀 ∥ 𝑁 → (𝑁 ∥ 𝑀 → ((abs‘𝑀) ≤ (abs‘𝑁) → (abs‘𝑀) = (abs‘𝑁)))))
72	71	com34 82	. . . . . . 7 ⊢ ((𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ) → (𝑀 ∥ 𝑁 → ((abs‘𝑀) ≤ (abs‘𝑁) → (𝑁 ∥ 𝑀 → (abs‘𝑀) = (abs‘𝑁)))))
73	72	adantl 271	. . . . . 6 ⊢ ((¬ 𝑁 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → (𝑀 ∥ 𝑁 → ((abs‘𝑀) ≤ (abs‘𝑁) → (𝑁 ∥ 𝑀 → (abs‘𝑀) = (abs‘𝑁)))))
74	27, 73	mpdd 40	. . . . 5 ⊢ ((¬ 𝑁 = 0 ∧ (𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ)) → (𝑀 ∥ 𝑁 → (𝑁 ∥ 𝑀 → (abs‘𝑀) = (abs‘𝑁))))
75	74	expcom 114	. . . 4 ⊢ ((𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ) → (¬ 𝑁 = 0 → (𝑀 ∥ 𝑁 → (𝑁 ∥ 𝑀 → (abs‘𝑀) = (abs‘𝑁)))))
76		zdceq 8792	. . . . . . 7 ⊢ ((𝑁 ∈ ℤ ∧ 0 ∈ ℤ) → DECID 𝑁 = 0)
77	65, 76	mpan2 416	. . . . . 6 ⊢ (𝑁 ∈ ℤ → DECID 𝑁 = 0)
78		exmiddc 782	. . . . . 6 ⊢ (DECID 𝑁 = 0 → (𝑁 = 0 ∨ ¬ 𝑁 = 0))
79	77, 78	syl 14	. . . . 5 ⊢ (𝑁 ∈ ℤ → (𝑁 = 0 ∨ ¬ 𝑁 = 0))
80	79	adantl 271	. . . 4 ⊢ ((𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ) → (𝑁 = 0 ∨ ¬ 𝑁 = 0))
81	20, 75, 80	mpjaod 673	. . 3 ⊢ ((𝑀 ∈ ℤ ∧ 𝑁 ∈ ℤ) → (𝑀 ∥ 𝑁 → (𝑁 ∥ 𝑀 → (abs‘𝑀) = (abs‘𝑁))))
82	1, 81	mpcom 36	. 2 ⊢ (𝑀 ∥ 𝑁 → (𝑁 ∥ 𝑀 → (abs‘𝑀) = (abs‘𝑁)))
83	82	imp 122	1 ⊢ ((𝑀 ∥ 𝑁 ∧ 𝑁 ∥ 𝑀) → (abs‘𝑀) = (abs‘𝑁))

Syntax hints:  ¬ wn 3   → wi 4   ∧ wa 102   ↔ wb 103   ∨ wo 664  DECID wdc 780   = wceq 1289   ∈ wcel 1438   ≠ wne 2255   class class class wbr 3837  ‘cfv 5002  ℝcr 7328  0cc0 7329   ≤ cle 7502  ℤcz 8720  abscabs 10395   ∥ cdvds 10878

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-in1 579  ax-in2 580  ax-io 665  ax-5 1381  ax-7 1382  ax-gen 1383  ax-ie1 1427  ax-ie2 1428  ax-8 1440  ax-10 1441  ax-11 1442  ax-i12 1443  ax-bndl 1444  ax-4 1445  ax-13 1449  ax-14 1450  ax-17 1464  ax-i9 1468  ax-ial 1472  ax-i5r 1473  ax-ext 2070  ax-coll 3946  ax-sep 3949  ax-nul 3957  ax-pow 4001  ax-pr 4027  ax-un 4251  ax-setind 4343  ax-iinf 4393  ax-cnex 7415  ax-resscn 7416  ax-1cn 7417  ax-1re 7418  ax-icn 7419  ax-addcl 7420  ax-addrcl 7421  ax-mulcl 7422  ax-mulrcl 7423  ax-addcom 7424  ax-mulcom 7425  ax-addass 7426  ax-mulass 7427  ax-distr 7428  ax-i2m1 7429  ax-0lt1 7430  ax-1rid 7431  ax-0id 7432  ax-rnegex 7433  ax-precex 7434  ax-cnre 7435  ax-pre-ltirr 7436  ax-pre-ltwlin 7437  ax-pre-lttrn 7438  ax-pre-apti 7439  ax-pre-ltadd 7440  ax-pre-mulgt0 7441  ax-pre-mulext 7442  ax-arch 7443  ax-caucvg 7444

This theorem depends on definitions:  df-bi 115  df-dc 781  df-3or 925  df-3an 926  df-tru 1292  df-fal 1295  df-nf 1395  df-sb 1693  df-eu 1951  df-mo 1952  df-clab 2075  df-cleq 2081  df-clel 2084  df-nfc 2217  df-ne 2256  df-nel 2351  df-ral 2364  df-rex 2365  df-reu 2366  df-rmo 2367  df-rab 2368  df-v 2621  df-sbc 2839  df-csb 2932  df-dif 2999  df-un 3001  df-in 3003  df-ss 3010  df-nul 3285  df-if 3390  df-pw 3427  df-sn 3447  df-pr 3448  df-op 3450  df-uni 3649  df-int 3684  df-iun 3727  df-br 3838  df-opab 3892  df-mpt 3893  df-tr 3929  df-id 4111  df-po 4114  df-iso 4115  df-iord 4184  df-on 4186  df-ilim 4187  df-suc 4189  df-iom 4396  df-xp 4434  df-rel 4435  df-cnv 4436  df-co 4437  df-dm 4438  df-rn 4439  df-res 4440  df-ima 4441  df-iota 4967  df-fun 5004  df-fn 5005  df-f 5006  df-f1 5007  df-fo 5008  df-f1o 5009  df-fv 5010  df-riota 5590  df-ov 5637  df-oprab 5638  df-mpt2 5639  df-1st 5893  df-2nd 5894  df-recs 6052  df-frec 6138  df-pnf 7503  df-mnf 7504  df-xr 7505  df-ltxr 7506  df-le 7507  df-sub 7634  df-neg 7635  df-reap 8028  df-ap 8035  df-div 8114  df-inn 8395  df-2 8452  df-3 8453  df-4 8454  df-n0 8644  df-z 8721  df-uz 8989  df-q 9074  df-rp 9104  df-iseq 9818  df-seq3 9819  df-exp 9920  df-cj 10241  df-re 10242  df-im 10243  df-rsqrt 10396  df-abs 10397  df-dvds 10879

This theorem is referenced by:  dvdseq  10931