Theorem cdj3lem1 32458

Description: A property of "𝐴 and 𝐵 are completely disjoint subspaces." Part of Lemma 5 of [Holland] p. 1520. (Contributed by NM, 23-May-2005.) (New usage is discouraged.)

Hypotheses

Ref	Expression
cdj1.1	⊢ 𝐴 ∈ Sℋ
cdj1.2	⊢ 𝐵 ∈ Sℋ

Assertion

Ref	Expression
cdj3lem1	⊢ (∃𝑥 ∈ ℝ (0 < 𝑥 ∧ ∀𝑦 ∈ 𝐴 ∀𝑧 ∈ 𝐵 ((normℎ‘𝑦) + (normℎ‘𝑧)) ≤ (𝑥 · (normℎ‘(𝑦 +ℎ 𝑧)))) → (𝐴 ∩ 𝐵) = 0ℋ)

Distinct variable groups:   𝑥,𝑦,𝑧,𝐴   𝑥,𝐵,𝑦,𝑧

Proof of Theorem cdj3lem1

Dummy variable 𝑤 is distinct from all other variables.

Step	Hyp	Ref	Expression
1		elin 3915	. . . . . . . . . . . 12 ⊢ (𝑤 ∈ (𝐴 ∩ 𝐵) ↔ (𝑤 ∈ 𝐴 ∧ 𝑤 ∈ 𝐵))
2		cdj1.2	. . . . . . . . . . . . . 14 ⊢ 𝐵 ∈ Sℋ
3		neg1cn 12128	. . . . . . . . . . . . . 14 ⊢ -1 ∈ ℂ
4		shmulcl 31242	. . . . . . . . . . . . . 14 ⊢ ((𝐵 ∈ Sℋ ∧ -1 ∈ ℂ ∧ 𝑤 ∈ 𝐵) → (-1 ·ℎ 𝑤) ∈ 𝐵)
5	2, 3, 4	mp3an12 1453	. . . . . . . . . . . . 13 ⊢ (𝑤 ∈ 𝐵 → (-1 ·ℎ 𝑤) ∈ 𝐵)
6	5	anim2i 617	. . . . . . . . . . . 12 ⊢ ((𝑤 ∈ 𝐴 ∧ 𝑤 ∈ 𝐵) → (𝑤 ∈ 𝐴 ∧ (-1 ·ℎ 𝑤) ∈ 𝐵))
7	1, 6	sylbi 217	. . . . . . . . . . 11 ⊢ (𝑤 ∈ (𝐴 ∩ 𝐵) → (𝑤 ∈ 𝐴 ∧ (-1 ·ℎ 𝑤) ∈ 𝐵))
8		fveq2 6832	. . . . . . . . . . . . . 14 ⊢ (𝑦 = 𝑤 → (normℎ‘𝑦) = (normℎ‘𝑤))
9	8	oveq1d 7371	. . . . . . . . . . . . 13 ⊢ (𝑦 = 𝑤 → ((normℎ‘𝑦) + (normℎ‘𝑧)) = ((normℎ‘𝑤) + (normℎ‘𝑧)))
10		fvoveq1 7379	. . . . . . . . . . . . . 14 ⊢ (𝑦 = 𝑤 → (normℎ‘(𝑦 +ℎ 𝑧)) = (normℎ‘(𝑤 +ℎ 𝑧)))
11	10	oveq2d 7372	. . . . . . . . . . . . 13 ⊢ (𝑦 = 𝑤 → (𝑥 · (normℎ‘(𝑦 +ℎ 𝑧))) = (𝑥 · (normℎ‘(𝑤 +ℎ 𝑧))))
12	9, 11	breq12d 5109	. . . . . . . . . . . 12 ⊢ (𝑦 = 𝑤 → (((normℎ‘𝑦) + (normℎ‘𝑧)) ≤ (𝑥 · (normℎ‘(𝑦 +ℎ 𝑧))) ↔ ((normℎ‘𝑤) + (normℎ‘𝑧)) ≤ (𝑥 · (normℎ‘(𝑤 +ℎ 𝑧)))))
13		fveq2 6832	. . . . . . . . . . . . . 14 ⊢ (𝑧 = (-1 ·ℎ 𝑤) → (normℎ‘𝑧) = (normℎ‘(-1 ·ℎ 𝑤)))
14	13	oveq2d 7372	. . . . . . . . . . . . 13 ⊢ (𝑧 = (-1 ·ℎ 𝑤) → ((normℎ‘𝑤) + (normℎ‘𝑧)) = ((normℎ‘𝑤) + (normℎ‘(-1 ·ℎ 𝑤))))
15		oveq2 7364	. . . . . . . . . . . . . . 15 ⊢ (𝑧 = (-1 ·ℎ 𝑤) → (𝑤 +ℎ 𝑧) = (𝑤 +ℎ (-1 ·ℎ 𝑤)))
16	15	fveq2d 6836	. . . . . . . . . . . . . 14 ⊢ (𝑧 = (-1 ·ℎ 𝑤) → (normℎ‘(𝑤 +ℎ 𝑧)) = (normℎ‘(𝑤 +ℎ (-1 ·ℎ 𝑤))))
17	16	oveq2d 7372	. . . . . . . . . . . . 13 ⊢ (𝑧 = (-1 ·ℎ 𝑤) → (𝑥 · (normℎ‘(𝑤 +ℎ 𝑧))) = (𝑥 · (normℎ‘(𝑤 +ℎ (-1 ·ℎ 𝑤)))))
18	14, 17	breq12d 5109	. . . . . . . . . . . 12 ⊢ (𝑧 = (-1 ·ℎ 𝑤) → (((normℎ‘𝑤) + (normℎ‘𝑧)) ≤ (𝑥 · (normℎ‘(𝑤 +ℎ 𝑧))) ↔ ((normℎ‘𝑤) + (normℎ‘(-1 ·ℎ 𝑤))) ≤ (𝑥 · (normℎ‘(𝑤 +ℎ (-1 ·ℎ 𝑤))))))
19	12, 18	rspc2v 3585	. . . . . . . . . . 11 ⊢ ((𝑤 ∈ 𝐴 ∧ (-1 ·ℎ 𝑤) ∈ 𝐵) → (∀𝑦 ∈ 𝐴 ∀𝑧 ∈ 𝐵 ((normℎ‘𝑦) + (normℎ‘𝑧)) ≤ (𝑥 · (normℎ‘(𝑦 +ℎ 𝑧))) → ((normℎ‘𝑤) + (normℎ‘(-1 ·ℎ 𝑤))) ≤ (𝑥 · (normℎ‘(𝑤 +ℎ (-1 ·ℎ 𝑤))))))
20	7, 19	syl 17	. . . . . . . . . 10 ⊢ (𝑤 ∈ (𝐴 ∩ 𝐵) → (∀𝑦 ∈ 𝐴 ∀𝑧 ∈ 𝐵 ((normℎ‘𝑦) + (normℎ‘𝑧)) ≤ (𝑥 · (normℎ‘(𝑦 +ℎ 𝑧))) → ((normℎ‘𝑤) + (normℎ‘(-1 ·ℎ 𝑤))) ≤ (𝑥 · (normℎ‘(𝑤 +ℎ (-1 ·ℎ 𝑤))))))
21	20	adantl 481	. . . . . . . . 9 ⊢ ((𝑥 ∈ ℝ ∧ 𝑤 ∈ (𝐴 ∩ 𝐵)) → (∀𝑦 ∈ 𝐴 ∀𝑧 ∈ 𝐵 ((normℎ‘𝑦) + (normℎ‘𝑧)) ≤ (𝑥 · (normℎ‘(𝑦 +ℎ 𝑧))) → ((normℎ‘𝑤) + (normℎ‘(-1 ·ℎ 𝑤))) ≤ (𝑥 · (normℎ‘(𝑤 +ℎ (-1 ·ℎ 𝑤))))))
22		cdj1.1	. . . . . . . . . . . 12 ⊢ 𝐴 ∈ Sℋ
23	22, 2	shincli 31386	. . . . . . . . . . 11 ⊢ (𝐴 ∩ 𝐵) ∈ Sℋ
24	23	sheli 31238	. . . . . . . . . 10 ⊢ (𝑤 ∈ (𝐴 ∩ 𝐵) → 𝑤 ∈ ℋ)
25		normneg 31168	. . . . . . . . . . . . . . 15 ⊢ (𝑤 ∈ ℋ → (normℎ‘(-1 ·ℎ 𝑤)) = (normℎ‘𝑤))
26	25	oveq2d 7372	. . . . . . . . . . . . . 14 ⊢ (𝑤 ∈ ℋ → ((normℎ‘𝑤) + (normℎ‘(-1 ·ℎ 𝑤))) = ((normℎ‘𝑤) + (normℎ‘𝑤)))
27		normcl 31149	. . . . . . . . . . . . . . . 16 ⊢ (𝑤 ∈ ℋ → (normℎ‘𝑤) ∈ ℝ)
28	27	recnd 11158	. . . . . . . . . . . . . . 15 ⊢ (𝑤 ∈ ℋ → (normℎ‘𝑤) ∈ ℂ)
29	28	2timesd 12382	. . . . . . . . . . . . . 14 ⊢ (𝑤 ∈ ℋ → (2 · (normℎ‘𝑤)) = ((normℎ‘𝑤) + (normℎ‘𝑤)))
30	26, 29	eqtr4d 2772	. . . . . . . . . . . . 13 ⊢ (𝑤 ∈ ℋ → ((normℎ‘𝑤) + (normℎ‘(-1 ·ℎ 𝑤))) = (2 · (normℎ‘𝑤)))
31	30	adantl 481	. . . . . . . . . . . 12 ⊢ ((𝑥 ∈ ℝ ∧ 𝑤 ∈ ℋ) → ((normℎ‘𝑤) + (normℎ‘(-1 ·ℎ 𝑤))) = (2 · (normℎ‘𝑤)))
32		hvnegid 31051	. . . . . . . . . . . . . . . . 17 ⊢ (𝑤 ∈ ℋ → (𝑤 +ℎ (-1 ·ℎ 𝑤)) = 0ℎ)
33	32	fveq2d 6836	. . . . . . . . . . . . . . . 16 ⊢ (𝑤 ∈ ℋ → (normℎ‘(𝑤 +ℎ (-1 ·ℎ 𝑤))) = (normℎ‘0ℎ))
34		norm0 31152	. . . . . . . . . . . . . . . 16 ⊢ (normℎ‘0ℎ) = 0
35	33, 34	eqtrdi 2785	. . . . . . . . . . . . . . 15 ⊢ (𝑤 ∈ ℋ → (normℎ‘(𝑤 +ℎ (-1 ·ℎ 𝑤))) = 0)
36	35	oveq2d 7372	. . . . . . . . . . . . . 14 ⊢ (𝑤 ∈ ℋ → (𝑥 · (normℎ‘(𝑤 +ℎ (-1 ·ℎ 𝑤)))) = (𝑥 · 0))
37		recn 11114	. . . . . . . . . . . . . . 15 ⊢ (𝑥 ∈ ℝ → 𝑥 ∈ ℂ)
38	37	mul01d 11330	. . . . . . . . . . . . . 14 ⊢ (𝑥 ∈ ℝ → (𝑥 · 0) = 0)
39	36, 38	sylan9eqr 2791	. . . . . . . . . . . . 13 ⊢ ((𝑥 ∈ ℝ ∧ 𝑤 ∈ ℋ) → (𝑥 · (normℎ‘(𝑤 +ℎ (-1 ·ℎ 𝑤)))) = 0)
40		2t0e0 12307	. . . . . . . . . . . . 13 ⊢ (2 · 0) = 0
41	39, 40	eqtr4di 2787	. . . . . . . . . . . 12 ⊢ ((𝑥 ∈ ℝ ∧ 𝑤 ∈ ℋ) → (𝑥 · (normℎ‘(𝑤 +ℎ (-1 ·ℎ 𝑤)))) = (2 · 0))
42	31, 41	breq12d 5109	. . . . . . . . . . 11 ⊢ ((𝑥 ∈ ℝ ∧ 𝑤 ∈ ℋ) → (((normℎ‘𝑤) + (normℎ‘(-1 ·ℎ 𝑤))) ≤ (𝑥 · (normℎ‘(𝑤 +ℎ (-1 ·ℎ 𝑤)))) ↔ (2 · (normℎ‘𝑤)) ≤ (2 · 0)))
43		0re 11132	. . . . . . . . . . . . . . 15 ⊢ 0 ∈ ℝ
44		letri3 11216	. . . . . . . . . . . . . . 15 ⊢ (((normℎ‘𝑤) ∈ ℝ ∧ 0 ∈ ℝ) → ((normℎ‘𝑤) = 0 ↔ ((normℎ‘𝑤) ≤ 0 ∧ 0 ≤ (normℎ‘𝑤))))
45	27, 43, 44	sylancl 586	. . . . . . . . . . . . . 14 ⊢ (𝑤 ∈ ℋ → ((normℎ‘𝑤) = 0 ↔ ((normℎ‘𝑤) ≤ 0 ∧ 0 ≤ (normℎ‘𝑤))))
46		normge0 31150	. . . . . . . . . . . . . . 15 ⊢ (𝑤 ∈ ℋ → 0 ≤ (normℎ‘𝑤))
47	46	biantrud 531	. . . . . . . . . . . . . 14 ⊢ (𝑤 ∈ ℋ → ((normℎ‘𝑤) ≤ 0 ↔ ((normℎ‘𝑤) ≤ 0 ∧ 0 ≤ (normℎ‘𝑤))))
48		2re 12217	. . . . . . . . . . . . . . . . 17 ⊢ 2 ∈ ℝ
49		2pos 12246	. . . . . . . . . . . . . . . . 17 ⊢ 0 < 2
50	48, 49	pm3.2i 470	. . . . . . . . . . . . . . . 16 ⊢ (2 ∈ ℝ ∧ 0 < 2)
51		lemul2 11992	. . . . . . . . . . . . . . . 16 ⊢ (((normℎ‘𝑤) ∈ ℝ ∧ 0 ∈ ℝ ∧ (2 ∈ ℝ ∧ 0 < 2)) → ((normℎ‘𝑤) ≤ 0 ↔ (2 · (normℎ‘𝑤)) ≤ (2 · 0)))
52	43, 50, 51	mp3an23 1455	. . . . . . . . . . . . . . 15 ⊢ ((normℎ‘𝑤) ∈ ℝ → ((normℎ‘𝑤) ≤ 0 ↔ (2 · (normℎ‘𝑤)) ≤ (2 · 0)))
53	27, 52	syl 17	. . . . . . . . . . . . . 14 ⊢ (𝑤 ∈ ℋ → ((normℎ‘𝑤) ≤ 0 ↔ (2 · (normℎ‘𝑤)) ≤ (2 · 0)))
54	45, 47, 53	3bitr2rd 308	. . . . . . . . . . . . 13 ⊢ (𝑤 ∈ ℋ → ((2 · (normℎ‘𝑤)) ≤ (2 · 0) ↔ (normℎ‘𝑤) = 0))
55		norm-i 31153	. . . . . . . . . . . . 13 ⊢ (𝑤 ∈ ℋ → ((normℎ‘𝑤) = 0 ↔ 𝑤 = 0ℎ))
56	54, 55	bitrd 279	. . . . . . . . . . . 12 ⊢ (𝑤 ∈ ℋ → ((2 · (normℎ‘𝑤)) ≤ (2 · 0) ↔ 𝑤 = 0ℎ))
57	56	adantl 481	. . . . . . . . . . 11 ⊢ ((𝑥 ∈ ℝ ∧ 𝑤 ∈ ℋ) → ((2 · (normℎ‘𝑤)) ≤ (2 · 0) ↔ 𝑤 = 0ℎ))
58	42, 57	bitrd 279	. . . . . . . . . 10 ⊢ ((𝑥 ∈ ℝ ∧ 𝑤 ∈ ℋ) → (((normℎ‘𝑤) + (normℎ‘(-1 ·ℎ 𝑤))) ≤ (𝑥 · (normℎ‘(𝑤 +ℎ (-1 ·ℎ 𝑤)))) ↔ 𝑤 = 0ℎ))
59	24, 58	sylan2 593	. . . . . . . . 9 ⊢ ((𝑥 ∈ ℝ ∧ 𝑤 ∈ (𝐴 ∩ 𝐵)) → (((normℎ‘𝑤) + (normℎ‘(-1 ·ℎ 𝑤))) ≤ (𝑥 · (normℎ‘(𝑤 +ℎ (-1 ·ℎ 𝑤)))) ↔ 𝑤 = 0ℎ))
60	21, 59	sylibd 239	. . . . . . . 8 ⊢ ((𝑥 ∈ ℝ ∧ 𝑤 ∈ (𝐴 ∩ 𝐵)) → (∀𝑦 ∈ 𝐴 ∀𝑧 ∈ 𝐵 ((normℎ‘𝑦) + (normℎ‘𝑧)) ≤ (𝑥 · (normℎ‘(𝑦 +ℎ 𝑧))) → 𝑤 = 0ℎ))
61	60	impancom 451	. . . . . . 7 ⊢ ((𝑥 ∈ ℝ ∧ ∀𝑦 ∈ 𝐴 ∀𝑧 ∈ 𝐵 ((normℎ‘𝑦) + (normℎ‘𝑧)) ≤ (𝑥 · (normℎ‘(𝑦 +ℎ 𝑧)))) → (𝑤 ∈ (𝐴 ∩ 𝐵) → 𝑤 = 0ℎ))
62		elch0 31278	. . . . . . 7 ⊢ (𝑤 ∈ 0ℋ ↔ 𝑤 = 0ℎ)
63	61, 62	imbitrrdi 252	. . . . . 6 ⊢ ((𝑥 ∈ ℝ ∧ ∀𝑦 ∈ 𝐴 ∀𝑧 ∈ 𝐵 ((normℎ‘𝑦) + (normℎ‘𝑧)) ≤ (𝑥 · (normℎ‘(𝑦 +ℎ 𝑧)))) → (𝑤 ∈ (𝐴 ∩ 𝐵) → 𝑤 ∈ 0ℋ))
64	63	ssrdv 3937	. . . . 5 ⊢ ((𝑥 ∈ ℝ ∧ ∀𝑦 ∈ 𝐴 ∀𝑧 ∈ 𝐵 ((normℎ‘𝑦) + (normℎ‘𝑧)) ≤ (𝑥 · (normℎ‘(𝑦 +ℎ 𝑧)))) → (𝐴 ∩ 𝐵) ⊆ 0ℋ)
65	64	ex 412	. . . 4 ⊢ (𝑥 ∈ ℝ → (∀𝑦 ∈ 𝐴 ∀𝑧 ∈ 𝐵 ((normℎ‘𝑦) + (normℎ‘𝑧)) ≤ (𝑥 · (normℎ‘(𝑦 +ℎ 𝑧))) → (𝐴 ∩ 𝐵) ⊆ 0ℋ))
66		shle0 31466	. . . . 5 ⊢ ((𝐴 ∩ 𝐵) ∈ Sℋ → ((𝐴 ∩ 𝐵) ⊆ 0ℋ ↔ (𝐴 ∩ 𝐵) = 0ℋ))
67	23, 66	ax-mp 5	. . . 4 ⊢ ((𝐴 ∩ 𝐵) ⊆ 0ℋ ↔ (𝐴 ∩ 𝐵) = 0ℋ)
68	65, 67	imbitrdi 251	. . 3 ⊢ (𝑥 ∈ ℝ → (∀𝑦 ∈ 𝐴 ∀𝑧 ∈ 𝐵 ((normℎ‘𝑦) + (normℎ‘𝑧)) ≤ (𝑥 · (normℎ‘(𝑦 +ℎ 𝑧))) → (𝐴 ∩ 𝐵) = 0ℋ))
69	68	adantld 490	. 2 ⊢ (𝑥 ∈ ℝ → ((0 < 𝑥 ∧ ∀𝑦 ∈ 𝐴 ∀𝑧 ∈ 𝐵 ((normℎ‘𝑦) + (normℎ‘𝑧)) ≤ (𝑥 · (normℎ‘(𝑦 +ℎ 𝑧)))) → (𝐴 ∩ 𝐵) = 0ℋ))
70	69	rexlimiv 3128	1 ⊢ (∃𝑥 ∈ ℝ (0 < 𝑥 ∧ ∀𝑦 ∈ 𝐴 ∀𝑧 ∈ 𝐵 ((normℎ‘𝑦) + (normℎ‘𝑧)) ≤ (𝑥 · (normℎ‘(𝑦 +ℎ 𝑧)))) → (𝐴 ∩ 𝐵) = 0ℋ)

Syntax hints:   → wi 4   ↔ wb 206   ∧ wa 395   = wceq 1541   ∈ wcel 2113  ∀wral 3049  ∃wrex 3058   ∩ cin 3898   ⊆ wss 3899   class class class wbr 5096  ‘cfv 6490  (class class class)co 7356  ℂcc 11022  ℝcr 11023  0cc0 11024  1c1 11025   + caddc 11027   · cmul 11029   < clt 11164   ≤ cle 11165  -cneg 11363  2c2 12198   ℋchba 30943   +_ℎ cva 30944   ·_ℎ csm 30945  norm_ℎcno 30947  0_ℎc0v 30948   S_ℋ csh 30952  0_ℋc0h 30959

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1796  ax-4 1810  ax-5 1911  ax-6 1968  ax-7 2009  ax-8 2115  ax-9 2123  ax-10 2146  ax-11 2162  ax-12 2182  ax-ext 2706  ax-sep 5239  ax-nul 5249  ax-pow 5308  ax-pr 5375  ax-un 7678  ax-cnex 11080  ax-resscn 11081  ax-1cn 11082  ax-icn 11083  ax-addcl 11084  ax-addrcl 11085  ax-mulcl 11086  ax-mulrcl 11087  ax-mulcom 11088  ax-addass 11089  ax-mulass 11090  ax-distr 11091  ax-i2m1 11092  ax-1ne0 11093  ax-1rid 11094  ax-rnegex 11095  ax-rrecex 11096  ax-cnre 11097  ax-pre-lttri 11098  ax-pre-lttrn 11099  ax-pre-ltadd 11100  ax-pre-mulgt0 11101  ax-pre-sup 11102  ax-hilex 31023  ax-hfvadd 31024  ax-hvcom 31025  ax-hv0cl 31027  ax-hvaddid 31028  ax-hfvmul 31029  ax-hvmulid 31030  ax-hvmulass 31031  ax-hvdistr1 31032  ax-hvdistr2 31033  ax-hvmul0 31034  ax-hfi 31103  ax-his1 31106  ax-his3 31108  ax-his4 31109

This theorem depends on definitions:  df-bi 207  df-an 396  df-or 848  df-3or 1087  df-3an 1088  df-tru 1544  df-fal 1554  df-ex 1781  df-nf 1785  df-sb 2068  df-mo 2537  df-eu 2567  df-clab 2713  df-cleq 2726  df-clel 2809  df-nfc 2883  df-ne 2931  df-nel 3035  df-ral 3050  df-rex 3059  df-rmo 3348  df-reu 3349  df-rab 3398  df-v 3440  df-sbc 3739  df-csb 3848  df-dif 3902  df-un 3904  df-in 3906  df-ss 3916  df-pss 3919  df-nul 4284  df-if 4478  df-pw 4554  df-sn 4579  df-pr 4581  df-op 4585  df-uni 4862  df-int 4901  df-iun 4946  df-br 5097  df-opab 5159  df-mpt 5178  df-tr 5204  df-id 5517  df-eprel 5522  df-po 5530  df-so 5531  df-fr 5575  df-we 5577  df-xp 5628  df-rel 5629  df-cnv 5630  df-co 5631  df-dm 5632  df-rn 5633  df-res 5634  df-ima 5635  df-pred 6257  df-ord 6318  df-on 6319  df-lim 6320  df-suc 6321  df-iota 6446  df-fun 6492  df-fn 6493  df-f 6494  df-f1 6495  df-fo 6496  df-f1o 6497  df-fv 6498  df-riota 7313  df-ov 7359  df-oprab 7360  df-mpo 7361  df-om 7807  df-2nd 7932  df-frecs 8221  df-wrecs 8252  df-recs 8301  df-rdg 8339  df-er 8633  df-en 8882  df-dom 8883  df-sdom 8884  df-sup 9343  df-pnf 11166  df-mnf 11167  df-xr 11168  df-ltxr 11169  df-le 11170  df-sub 11364  df-neg 11365  df-div 11793  df-nn 12144  df-2 12206  df-3 12207  df-n0 12400  df-z 12487  df-uz 12750  df-rp 12904  df-seq 13923  df-exp 13983  df-cj 15020  df-re 15021  df-im 15022  df-sqrt 15156  df-abs 15157  df-hnorm 30992  df-hvsub 30995  df-sh 31231  df-ch0 31277

This theorem is referenced by:  cdj3lem2b  32461  cdj3i  32465