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Theorem cfflb 10340
Description: If there is a cofinal map from 𝐵 to 𝐴, then 𝐵 is at least (cf‘𝐴). This theorem and cff1 10339 motivate the picture of (cf‘𝐴) as the greatest lower bound of the domain of cofinal maps into 𝐴. (Contributed by Mario Carneiro, 28-Feb-2013.)
Assertion
Ref Expression
cfflb ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (∃𝑓(𝑓:𝐵⟶𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑤 ∈ 𝐵 𝑧 ⊆ (𝑓‘𝑤)) → (cf‘𝐴) ⊆ 𝐵))
Distinct variable groups:   𝐴,𝑓,𝑤,𝑧   𝐵,𝑓,𝑤,𝑧

Proof of Theorem cfflb
Dummy variables 𝑠 𝑥 𝑦 are mutually distinct and distinct from all other variables.
StepHypRef Expression
1 frn 6717 . . . . . . 7 (𝑓:𝐵⟶𝐴 → ran 𝑓 ⊆ 𝐴)
21adantr 486 . . . . . 6 ((𝑓:𝐵⟶𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑤 ∈ 𝐵 𝑧 ⊆ (𝑓‘𝑤)) → ran 𝑓 ⊆ 𝐴)
3 ffn 6709 . . . . . . . . . . 11 (𝑓:𝐵⟶𝐴 → 𝑓 Fn 𝐵)
4 fnfvelrn 7080 . . . . . . . . . . 11 ((𝑓 Fn 𝐵 ∧ 𝑤 ∈ 𝐵) → (𝑓‘𝑤) ∈ ran 𝑓)
53, 4sylan 592 . . . . . . . . . 10 ((𝑓:𝐵⟶𝐴 ∧ 𝑤 ∈ 𝐵) → (𝑓‘𝑤) ∈ ran 𝑓)
6 sseq2 3934 . . . . . . . . . . 11 (𝑠 = (𝑓‘𝑤) → (𝑧 ⊆ 𝑠 ↔ 𝑧 ⊆ (𝑓‘𝑤)))
76rspcev 3576 . . . . . . . . . 10 (((𝑓‘𝑤) ∈ ran 𝑓 ∧ 𝑧 ⊆ (𝑓‘𝑤)) → ∃𝑠 ∈ ran 𝑓 𝑧 ⊆ 𝑠)
85, 7sylan 592 . . . . . . . . 9 (((𝑓:𝐵⟶𝐴 ∧ 𝑤 ∈ 𝐵) ∧ 𝑧 ⊆ (𝑓‘𝑤)) → ∃𝑠 ∈ ran 𝑓 𝑧 ⊆ 𝑠)
98rexlimdva2 3165 . . . . . . . 8 (𝑓:𝐵⟶𝐴 → (∃𝑤 ∈ 𝐵 𝑧 ⊆ (𝑓‘𝑤) → ∃𝑠 ∈ ran 𝑓 𝑧 ⊆ 𝑠))
109ralimdv 3176 . . . . . . 7 (𝑓:𝐵⟶𝐴 → (∀𝑧 ∈ 𝐴 ∃𝑤 ∈ 𝐵 𝑧 ⊆ (𝑓‘𝑤) → ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ ran 𝑓 𝑧 ⊆ 𝑠))
1110imp 412 . . . . . 6 ((𝑓:𝐵⟶𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑤 ∈ 𝐵 𝑧 ⊆ (𝑓‘𝑤)) → ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ ran 𝑓 𝑧 ⊆ 𝑠)
122, 11jca 521 . . . . 5 ((𝑓:𝐵⟶𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑤 ∈ 𝐵 𝑧 ⊆ (𝑓‘𝑤)) → (ran 𝑓 ⊆ 𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ ran 𝑓 𝑧 ⊆ 𝑠))
13 fvex 6898 . . . . . 6 (card‘ran 𝑓) ∈ V
14 cfval 10327 . . . . . . . . . . 11 (𝐴 ∈ On → (cf‘𝐴) = ∩ {𝑥 ∣ ∃𝑦(𝑥 = (card‘𝑦) ∧ (𝑦 ⊆ 𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ 𝑦 𝑧 ⊆ 𝑠))})
1514adantr 486 . . . . . . . . . 10 ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (cf‘𝐴) = ∩ {𝑥 ∣ ∃𝑦(𝑥 = (card‘𝑦) ∧ (𝑦 ⊆ 𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ 𝑦 𝑧 ⊆ 𝑠))})
16153ad2ant2 1152 . . . . . . . . 9 ((𝑥 = (card‘ran 𝑓) ∧ (𝐴 ∈ On ∧ 𝐵 ∈ On) ∧ (ran 𝑓 ⊆ 𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ ran 𝑓 𝑧 ⊆ 𝑠)) → (cf‘𝐴) = ∩ {𝑥 ∣ ∃𝑦(𝑥 = (card‘𝑦) ∧ (𝑦 ⊆ 𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ 𝑦 𝑧 ⊆ 𝑠))})
17 vex 3454 . . . . . . . . . . . . . 14 𝑓 ∈ V
1817rnex 7922 . . . . . . . . . . . . 13 ran 𝑓 ∈ V
19 fveq2 6885 . . . . . . . . . . . . . . 15 (𝑦 = ran 𝑓 → (card‘𝑦) = (card‘ran 𝑓))
2019eqeq2d 2771 . . . . . . . . . . . . . 14 (𝑦 = ran 𝑓 → (𝑥 = (card‘𝑦) ↔ 𝑥 = (card‘ran 𝑓)))
21 sseq1 3933 . . . . . . . . . . . . . . 15 (𝑦 = ran 𝑓 → (𝑦 ⊆ 𝐴 ↔ ran 𝑓 ⊆ 𝐴))
22 rexeq 3315 . . . . . . . . . . . . . . . 16 (𝑦 = ran 𝑓 → (∃𝑠 ∈ 𝑦 𝑧 ⊆ 𝑠 ↔ ∃𝑠 ∈ ran 𝑓 𝑧 ⊆ 𝑠))
2322ralbidv 3185 . . . . . . . . . . . . . . 15 (𝑦 = ran 𝑓 → (∀𝑧 ∈ 𝐴 ∃𝑠 ∈ 𝑦 𝑧 ⊆ 𝑠 ↔ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ ran 𝑓 𝑧 ⊆ 𝑠))
2421, 23anbi12d 644 . . . . . . . . . . . . . 14 (𝑦 = ran 𝑓 → ((𝑦 ⊆ 𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ 𝑦 𝑧 ⊆ 𝑠) ↔ (ran 𝑓 ⊆ 𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ ran 𝑓 𝑧 ⊆ 𝑠)))
2520, 24anbi12d 644 . . . . . . . . . . . . 13 (𝑦 = ran 𝑓 → ((𝑥 = (card‘𝑦) ∧ (𝑦 ⊆ 𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ 𝑦 𝑧 ⊆ 𝑠)) ↔ (𝑥 = (card‘ran 𝑓) ∧ (ran 𝑓 ⊆ 𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ ran 𝑓 𝑧 ⊆ 𝑠))))
2618, 25spcev 3560 . . . . . . . . . . . 12 ((𝑥 = (card‘ran 𝑓) ∧ (ran 𝑓 ⊆ 𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ ran 𝑓 𝑧 ⊆ 𝑠)) → ∃𝑦(𝑥 = (card‘𝑦) ∧ (𝑦 ⊆ 𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ 𝑦 𝑧 ⊆ 𝑠)))
27 abid 2742 . . . . . . . . . . . 12 (𝑥 ∈ {𝑥 ∣ ∃𝑦(𝑥 = (card‘𝑦) ∧ (𝑦 ⊆ 𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ 𝑦 𝑧 ⊆ 𝑠))} ↔ ∃𝑦(𝑥 = (card‘𝑦) ∧ (𝑦 ⊆ 𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ 𝑦 𝑧 ⊆ 𝑠)))
2826, 27sylibr 237 . . . . . . . . . . 11 ((𝑥 = (card‘ran 𝑓) ∧ (ran 𝑓 ⊆ 𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ ran 𝑓 𝑧 ⊆ 𝑠)) → 𝑥 ∈ {𝑥 ∣ ∃𝑦(𝑥 = (card‘𝑦) ∧ (𝑦 ⊆ 𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ 𝑦 𝑧 ⊆ 𝑠))})
29 intss1 4922 . . . . . . . . . . 11 (𝑥 ∈ {𝑥 ∣ ∃𝑦(𝑥 = (card‘𝑦) ∧ (𝑦 ⊆ 𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ 𝑦 𝑧 ⊆ 𝑠))} → ∩ {𝑥 ∣ ∃𝑦(𝑥 = (card‘𝑦) ∧ (𝑦 ⊆ 𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ 𝑦 𝑧 ⊆ 𝑠))} ⊆ 𝑥)
3028, 29syl 18 . . . . . . . . . 10 ((𝑥 = (card‘ran 𝑓) ∧ (ran 𝑓 ⊆ 𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ ran 𝑓 𝑧 ⊆ 𝑠)) → ∩ {𝑥 ∣ ∃𝑦(𝑥 = (card‘𝑦) ∧ (𝑦 ⊆ 𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ 𝑦 𝑧 ⊆ 𝑠))} ⊆ 𝑥)
31303adant2 1149 . . . . . . . . 9 ((𝑥 = (card‘ran 𝑓) ∧ (𝐴 ∈ On ∧ 𝐵 ∈ On) ∧ (ran 𝑓 ⊆ 𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ ran 𝑓 𝑧 ⊆ 𝑠)) → ∩ {𝑥 ∣ ∃𝑦(𝑥 = (card‘𝑦) ∧ (𝑦 ⊆ 𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ 𝑦 𝑧 ⊆ 𝑠))} ⊆ 𝑥)
3216, 31eqsstrd 3942 . . . . . . . 8 ((𝑥 = (card‘ran 𝑓) ∧ (𝐴 ∈ On ∧ 𝐵 ∈ On) ∧ (ran 𝑓 ⊆ 𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ ran 𝑓 𝑧 ⊆ 𝑠)) → (cf‘𝐴) ⊆ 𝑥)
33323expib 1140 . . . . . . 7 (𝑥 = (card‘ran 𝑓) → (((𝐴 ∈ On ∧ 𝐵 ∈ On) ∧ (ran 𝑓 ⊆ 𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ ran 𝑓 𝑧 ⊆ 𝑠)) → (cf‘𝐴) ⊆ 𝑥))
34 sseq2 3934 . . . . . . 7 (𝑥 = (card‘ran 𝑓) → ((cf‘𝐴) ⊆ 𝑥 ↔ (cf‘𝐴) ⊆ (card‘ran 𝑓)))
3533, 34sylibd 242 . . . . . 6 (𝑥 = (card‘ran 𝑓) → (((𝐴 ∈ On ∧ 𝐵 ∈ On) ∧ (ran 𝑓 ⊆ 𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ ran 𝑓 𝑧 ⊆ 𝑠)) → (cf‘𝐴) ⊆ (card‘ran 𝑓)))
3613, 35vtocle 3518 . . . . 5 (((𝐴 ∈ On ∧ 𝐵 ∈ On) ∧ (ran 𝑓 ⊆ 𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑠 ∈ ran 𝑓 𝑧 ⊆ 𝑠)) → (cf‘𝐴) ⊆ (card‘ran 𝑓))
3712, 36sylan2 605 . . . 4 (((𝐴 ∈ On ∧ 𝐵 ∈ On) ∧ (𝑓:𝐵⟶𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑤 ∈ 𝐵 𝑧 ⊆ (𝑓‘𝑤))) → (cf‘𝐴) ⊆ (card‘ran 𝑓))
38 cardidm 10043 . . . . . . 7 (card‘(card‘ran 𝑓)) = (card‘ran 𝑓)
39 onss 7799 . . . . . . . . . . . . . 14 (𝐴 ∈ On → 𝐴 ⊆ On)
401, 39sylan9ssr 3922 . . . . . . . . . . . . 13 ((𝐴 ∈ On ∧ 𝑓:𝐵⟶𝐴) → ran 𝑓 ⊆ On)
41403adant2 1149 . . . . . . . . . . . 12 ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝑓:𝐵⟶𝐴) → ran 𝑓 ⊆ On)
42 onssnum 10122 . . . . . . . . . . . 12 ((ran 𝑓 ∈ V ∧ ran 𝑓 ⊆ On) → ran 𝑓 ∈ dom card)
4318, 41, 42sylancr 599 . . . . . . . . . . 11 ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝑓:𝐵⟶𝐴) → ran 𝑓 ∈ dom card)
44 cardid2 10037 . . . . . . . . . . 11 (ran 𝑓 ∈ dom card → (card‘ran 𝑓) ≈ ran 𝑓)
4543, 44syl 18 . . . . . . . . . 10 ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝑓:𝐵⟶𝐴) → (card‘ran 𝑓) ≈ ran 𝑓)
46 onenon 10033 . . . . . . . . . . . . 13 (𝐵 ∈ On → 𝐵 ∈ dom card)
47 dffn4 6802 . . . . . . . . . . . . . 14 (𝑓 Fn 𝐵 ↔ 𝑓:𝐵–onto→ran 𝑓)
483, 47sylib 221 . . . . . . . . . . . . 13 (𝑓:𝐵⟶𝐴 → 𝑓:𝐵–onto→ran 𝑓)
49 fodomnum 10139 . . . . . . . . . . . . 13 (𝐵 ∈ dom card → (𝑓:𝐵–onto→ran 𝑓 → ran 𝑓 ≼ 𝐵))
5046, 48, 49syl2im 41 . . . . . . . . . . . 12 (𝐵 ∈ On → (𝑓:𝐵⟶𝐴 → ran 𝑓 ≼ 𝐵))
5150imp 412 . . . . . . . . . . 11 ((𝐵 ∈ On ∧ 𝑓:𝐵⟶𝐴) → ran 𝑓 ≼ 𝐵)
52513adant1 1148 . . . . . . . . . 10 ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝑓:𝐵⟶𝐴) → ran 𝑓 ≼ 𝐵)
53 endomtr 9042 . . . . . . . . . 10 (((card‘ran 𝑓) ≈ ran 𝑓 ∧ ran 𝑓 ≼ 𝐵) → (card‘ran 𝑓) ≼ 𝐵)
5445, 52, 53syl2anc 596 . . . . . . . . 9 ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝑓:𝐵⟶𝐴) → (card‘ran 𝑓) ≼ 𝐵)
55 cardon 10028 . . . . . . . . . . . 12 (card‘ran 𝑓) ∈ On
56 onenon 10033 . . . . . . . . . . . 12 ((card‘ran 𝑓) ∈ On → (card‘ran 𝑓) ∈ dom card)
5755, 56ax-mp 5 . . . . . . . . . . 11 (card‘ran 𝑓) ∈ dom card
58 carddom2 10061 . . . . . . . . . . 11 (((card‘ran 𝑓) ∈ dom card ∧ 𝐵 ∈ dom card) → ((card‘(card‘ran 𝑓)) ⊆ (card‘𝐵) ↔ (card‘ran 𝑓) ≼ 𝐵))
5957, 46, 58sylancr 599 . . . . . . . . . 10 (𝐵 ∈ On → ((card‘(card‘ran 𝑓)) ⊆ (card‘𝐵) ↔ (card‘ran 𝑓) ≼ 𝐵))
60593ad2ant2 1152 . . . . . . . . 9 ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝑓:𝐵⟶𝐴) → ((card‘(card‘ran 𝑓)) ⊆ (card‘𝐵) ↔ (card‘ran 𝑓) ≼ 𝐵))
6154, 60mpbird 260 . . . . . . . 8 ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝑓:𝐵⟶𝐴) → (card‘(card‘ran 𝑓)) ⊆ (card‘𝐵))
62 cardonle 10041 . . . . . . . . 9 (𝐵 ∈ On → (card‘𝐵) ⊆ 𝐵)
63623ad2ant2 1152 . . . . . . . 8 ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝑓:𝐵⟶𝐴) → (card‘𝐵) ⊆ 𝐵)
6461, 63sstrd 3918 . . . . . . 7 ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝑓:𝐵⟶𝐴) → (card‘(card‘ran 𝑓)) ⊆ 𝐵)
6538, 64eqsstrrid 3947 . . . . . 6 ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝑓:𝐵⟶𝐴) → (card‘ran 𝑓) ⊆ 𝐵)
66653expa 1136 . . . . 5 (((𝐴 ∈ On ∧ 𝐵 ∈ On) ∧ 𝑓:𝐵⟶𝐴) → (card‘ran 𝑓) ⊆ 𝐵)
6766adantrr 730 . . . 4 (((𝐴 ∈ On ∧ 𝐵 ∈ On) ∧ (𝑓:𝐵⟶𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑤 ∈ 𝐵 𝑧 ⊆ (𝑓‘𝑤))) → (card‘ran 𝑓) ⊆ 𝐵)
6837, 67sstrd 3918 . . 3 (((𝐴 ∈ On ∧ 𝐵 ∈ On) ∧ (𝑓:𝐵⟶𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑤 ∈ 𝐵 𝑧 ⊆ (𝑓‘𝑤))) → (cf‘𝐴) ⊆ 𝐵)
6968ex 418 . 2 ((𝐴 ∈ On ∧ 𝐵 ∈ On) → ((𝑓:𝐵⟶𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑤 ∈ 𝐵 𝑧 ⊆ (𝑓‘𝑤)) → (cf‘𝐴) ⊆ 𝐵))
7069exlimdv 1965 1 ((𝐴 ∈ On ∧ 𝐵 ∈ On) → (∃𝑓(𝑓:𝐵⟶𝐴 ∧ ∀𝑧 ∈ 𝐴 ∃𝑤 ∈ 𝐵 𝑧 ⊆ (𝑓‘𝑤)) → (cf‘𝐴) ⊆ 𝐵))
Colors of variables:    wff setvar class
This proof depends on syntax axioms:   → wi 4   ↔ wb 209   ∧ wa 401   ∧ w3a 1103   = wceq 1569  ∃wex 1811   ∈ wcel 2144  {cab 2738  ∀wral 3076  ∃wrex 3086  Vcvv 3450   ⊆ wss 3895  ∩ cint 4906   class class class wbr 5102  dom cdm 5650  ran crn 5651  Oncon0 6362   Fn wfn 6533  ⟶wf 6534  –onto→wfo 6536  ‘cfv 6538   ≈ cen 8973   ≼ cdom 8974  cardccrd 10019  cfccf 10021
This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1827  ax-4 1841  ax-5 1942  ax-6 1999  ax-7 2040  ax-8 2146  ax-9 2154  ax-10 2177  ax-11 2193  ax-12 2212  ax-ext 2732  ax-rep 5231  ax-sep 5248  ax-nul 5259  ax-pow 5326  ax-pr 5390  ax-un 7751
This proof depends on definitions:  df-bi 210  df-an 402  df-or 862  df-3or 1104  df-3an 1105  df-tru 1572  df-fal 1582  df-ex 1812  df-nf 1816  df-sb 2099  df-mo 2564  df-eu 2594  df-clab 2739  df-cleq 2752  df-clel 2835  df-nfc 2909  df-ne 2956  df-ral 3077  df-rex 3087  df-rmo 3365  df-reu 3366  df-rab 3413  df-v 3452  df-sbc 3739  df-csb 3847  df-ss 3896  df-pss 4014  df-dif 4047  df-in 4091  df-un 4151  df-nul 4279  df-if 4482  df-pw 4558  df-sn 4585  df-pr 4587  df-op 4835  df-uni 4867  df-int 4907  df-iun 4952  df-br 5103  df-opab 5167  df-mpt 5186  df-tr 5212  df-id 5545  df-eprel 5550  df-po 5558  df-so 5559  df-fr 5603  df-se 5604  df-we 5605  df-xp 5656  df-rel 5657  df-cnv 5658  df-co 5659  df-dm 5660  df-rn 5661  df-res 5662  df-ima 5663  df-pred 6304  df-ord 6365  df-on 6366  df-suc 6368  df-iota 6494  df-fun 6540  df-fn 6541  df-f 6542  df-f1 6543  df-fo 6544  df-f1o 6545  df-fv 6546  df-isom 6547  df-riota 7377  df-ov 7423  df-oprab 7424  df-mpo 7425  df-1st 8001  df-2nd 8002  df-frecs 8302  df-wrecs 8333  df-recs 8382  df-er 8720  df-map 8852  df-en 8977  df-dom 8978  df-sdom 8979  df-card 10023  df-cf 10025  df-acn 10026
This theorem is used by:  cfsmolem  10351  cfcoflem  10353  cfcof  10355  inar1  10863
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