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Theorem cfflb 10318
Description: If there is a cofinal map from 𝐵 to 𝐴, then 𝐵 is at least (cf‘𝐴). This theorem and cff1 10317 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 6709 . . . . . . 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 6701 . . . . . . . . . . 11 (𝑓:𝐵⟶𝐴 → 𝑓 Fn 𝐵)
4 fnfvelrn 7072 . . . . . . . . . . 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 3957 . . . . . . . . . . 11 (𝑠 = (𝑓‘𝑤) → (𝑧 ⊆ 𝑠 ↔ 𝑧 ⊆ (𝑓‘𝑤)))
76rspcev 3577 . . . . . . . . . 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 3166 . . . . . . . 8 (𝑓:𝐵⟶𝐴 → (∃𝑤 ∈ 𝐵 𝑧 ⊆ (𝑓‘𝑤) → ∃𝑠 ∈ ran 𝑓 𝑧 ⊆ 𝑠))
109ralimdv 3177 . . . . . . 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 6890 . . . . . 6 (card‘ran 𝑓) ∈ V
14 cfval 10305 . . . . . . . . . . 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 3455 . . . . . . . . . . . . . 14 𝑓 ∈ V
1817rnex 7911 . . . . . . . . . . . . 13 ran 𝑓 ∈ V
19 fveq2 6877 . . . . . . . . . . . . . . 15 (𝑦 = ran 𝑓 → (card‘𝑦) = (card‘ran 𝑓))
2019eqeq2d 2772 . . . . . . . . . . . . . 14 (𝑦 = ran 𝑓 → (𝑥 = (card‘𝑦) ↔ 𝑥 = (card‘ran 𝑓)))
21 sseq1 3956 . . . . . . . . . . . . . . 15 (𝑦 = ran 𝑓 → (𝑦 ⊆ 𝐴 ↔ ran 𝑓 ⊆ 𝐴))
22 rexeq 3316 . . . . . . . . . . . . . . . 16 (𝑦 = ran 𝑓 → (∃𝑠 ∈ 𝑦 𝑧 ⊆ 𝑠 ↔ ∃𝑠 ∈ ran 𝑓 𝑧 ⊆ 𝑠))
2322ralbidv 3186 . . . . . . . . . . . . . . 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 3561 . . . . . . . . . . . 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 2743 . . . . . . . . . . . 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 4923 . . . . . . . . . . 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 3965 . . . . . . . 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 3957 . . . . . . 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 3519 . . . . 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 10021 . . . . . . 7 (card‘(card‘ran 𝑓)) = (card‘ran 𝑓)
39 onss 7788 . . . . . . . . . . . . . 14 (𝐴 ∈ On → 𝐴 ⊆ On)
401, 39sylan9ssr 3945 . . . . . . . . . . . . 13 ((𝐴 ∈ On ∧ 𝑓:𝐵⟶𝐴) → ran 𝑓 ⊆ On)
41403adant2 1149 . . . . . . . . . . . 12 ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝑓:𝐵⟶𝐴) → ran 𝑓 ⊆ On)
42 onssnum 10100 . . . . . . . . . . . 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 10015 . . . . . . . . . . 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 10011 . . . . . . . . . . . . 13 (𝐵 ∈ On → 𝐵 ∈ dom card)
47 dffn4 6794 . . . . . . . . . . . . . 14 (𝑓 Fn 𝐵 ↔ 𝑓:𝐵–onto→ran 𝑓)
483, 47sylib 221 . . . . . . . . . . . . 13 (𝑓:𝐵⟶𝐴 → 𝑓:𝐵–onto→ran 𝑓)
49 fodomnum 10117 . . . . . . . . . . . . 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 9023 . . . . . . . . . 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 10006 . . . . . . . . . . . 12 (card‘ran 𝑓) ∈ On
56 onenon 10011 . . . . . . . . . . . 12 ((card‘ran 𝑓) ∈ On → (card‘ran 𝑓) ∈ dom card)
5755, 56ax-mp 5 . . . . . . . . . . 11 (card‘ran 𝑓) ∈ dom card
58 carddom2 10039 . . . . . . . . . . 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 10019 . . . . . . . . 9 (𝐵 ∈ On → (card‘𝐵) ⊆ 𝐵)
63623ad2ant2 1152 . . . . . . . 8 ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝑓:𝐵⟶𝐴) → (card‘𝐵) ⊆ 𝐵)
6461, 63sstrd 3941 . . . . . . 7 ((𝐴 ∈ On ∧ 𝐵 ∈ On ∧ 𝑓:𝐵⟶𝐴) → (card‘(card‘ran 𝑓)) ⊆ 𝐵)
6538, 64eqsstrrid 3970 . . . . . 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 3941 . . 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 1966 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 1570  ∃wex 1812   ∈ wcel 2145  {cab 2739  ∀wral 3077  ∃wrex 3087  Vcvv 3451   ⊆ wss 3899  ∩ cint 4907   class class class wbr 5103  dom cdm 5651  ran crn 5652  Oncon0 6355   Fn wfn 6526  ⟶wf 6527  –onto→wfo 6529  ‘cfv 6531   ≈ cen 8954   ≼ cdom 8955  cardccrd 9997  cfccf 9999
This proof depends on axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1828  ax-4 1842  ax-5 1943  ax-6 2000  ax-7 2041  ax-8 2147  ax-9 2155  ax-10 2178  ax-11 2194  ax-12 2213  ax-ext 2733  ax-rep 5232  ax-sep 5249  ax-nul 5260  ax-pow 5327  ax-pr 5391  ax-un 7740
This proof depends on definitions:  df-bi 210  df-an 402  df-or 862  df-3or 1104  df-3an 1105  df-tru 1573  df-fal 1583  df-ex 1813  df-nf 1817  df-sb 2100  df-mo 2565  df-eu 2595  df-clab 2740  df-cleq 2753  df-clel 2836  df-nfc 2910  df-ne 2957  df-ral 3078  df-rex 3088  df-rmo 3366  df-reu 3367  df-rab 3414  df-v 3453  df-sbc 3740  df-csb 3848  df-dif 3902  df-un 3904  df-in 3906  df-ss 3916  df-pss 3919  df-nul 4280  df-if 4483  df-pw 4559  df-sn 4585  df-pr 4587  df-op 4591  df-uni 4868  df-int 4908  df-iun 4953  df-br 5104  df-opab 5168  df-mpt 5187  df-tr 5213  df-id 5546  df-eprel 5551  df-po 5559  df-so 5560  df-fr 5604  df-se 5605  df-we 5606  df-xp 5657  df-rel 5658  df-cnv 5659  df-co 5660  df-dm 5661  df-rn 5662  df-res 5663  df-ima 5664  df-pred 6297  df-ord 6358  df-on 6359  df-suc 6361  df-iota 6487  df-fun 6533  df-fn 6534  df-f 6535  df-f1 6536  df-fo 6537  df-f1o 6538  df-fv 6539  df-isom 6540  df-riota 7369  df-ov 7415  df-oprab 7416  df-mpo 7417  df-1st 7990  df-2nd 7991  df-frecs 8283  df-wrecs 8314  df-recs 8363  df-er 8701  df-map 8833  df-en 8958  df-dom 8959  df-sdom 8960  df-card 10001  df-cf 10003  df-acn 10004
This theorem is used by:  cfsmolem  10329  cfcoflem  10331  cfcof  10333  inar1  10841
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