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Mirrors > Home > MPE Home > Th. List > dffr4 | Structured version Visualization version GIF version |
Description: Alternate definition of well-founded relation. (Contributed by Scott Fenton, 2-Feb-2011.) |
Ref | Expression |
---|---|
dffr4 | ⊢ (𝑅 Fr 𝐴 ↔ ∀𝑥((𝑥 ⊆ 𝐴 ∧ 𝑥 ≠ ∅) → ∃𝑦 ∈ 𝑥 Pred(𝑅, 𝑥, 𝑦) = ∅)) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | dffr3 5943 | . 2 ⊢ (𝑅 Fr 𝐴 ↔ ∀𝑥((𝑥 ⊆ 𝐴 ∧ 𝑥 ≠ ∅) → ∃𝑦 ∈ 𝑥 (𝑥 ∩ (◡𝑅 “ {𝑦})) = ∅)) | |
2 | df-pred 6129 | . . . . . 6 ⊢ Pred(𝑅, 𝑥, 𝑦) = (𝑥 ∩ (◡𝑅 “ {𝑦})) | |
3 | 2 | eqeq1i 2825 | . . . . 5 ⊢ (Pred(𝑅, 𝑥, 𝑦) = ∅ ↔ (𝑥 ∩ (◡𝑅 “ {𝑦})) = ∅) |
4 | 3 | rexbii 3242 | . . . 4 ⊢ (∃𝑦 ∈ 𝑥 Pred(𝑅, 𝑥, 𝑦) = ∅ ↔ ∃𝑦 ∈ 𝑥 (𝑥 ∩ (◡𝑅 “ {𝑦})) = ∅) |
5 | 4 | imbi2i 338 | . . 3 ⊢ (((𝑥 ⊆ 𝐴 ∧ 𝑥 ≠ ∅) → ∃𝑦 ∈ 𝑥 Pred(𝑅, 𝑥, 𝑦) = ∅) ↔ ((𝑥 ⊆ 𝐴 ∧ 𝑥 ≠ ∅) → ∃𝑦 ∈ 𝑥 (𝑥 ∩ (◡𝑅 “ {𝑦})) = ∅)) |
6 | 5 | albii 1820 | . 2 ⊢ (∀𝑥((𝑥 ⊆ 𝐴 ∧ 𝑥 ≠ ∅) → ∃𝑦 ∈ 𝑥 Pred(𝑅, 𝑥, 𝑦) = ∅) ↔ ∀𝑥((𝑥 ⊆ 𝐴 ∧ 𝑥 ≠ ∅) → ∃𝑦 ∈ 𝑥 (𝑥 ∩ (◡𝑅 “ {𝑦})) = ∅)) |
7 | 1, 6 | bitr4i 280 | 1 ⊢ (𝑅 Fr 𝐴 ↔ ∀𝑥((𝑥 ⊆ 𝐴 ∧ 𝑥 ≠ ∅) → ∃𝑦 ∈ 𝑥 Pred(𝑅, 𝑥, 𝑦) = ∅)) |
Colors of variables: wff setvar class |
Syntax hints: → wi 4 ↔ wb 208 ∧ wa 398 ∀wal 1535 = wceq 1537 ≠ wne 3011 ∃wrex 3134 ∩ cin 3918 ⊆ wss 3919 ∅c0 4274 {csn 4548 Fr wfr 5492 ◡ccnv 5535 “ cima 5539 Predcpred 6128 |
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 1970 ax-7 2015 ax-8 2116 ax-9 2124 ax-10 2145 ax-11 2161 ax-12 2177 ax-ext 2792 ax-sep 5184 ax-nul 5191 ax-pr 5311 |
This theorem depends on definitions: df-bi 209 df-an 399 df-or 844 df-3an 1085 df-tru 1540 df-ex 1781 df-nf 1785 df-sb 2070 df-mo 2622 df-eu 2653 df-clab 2799 df-cleq 2813 df-clel 2891 df-nfc 2959 df-ral 3138 df-rex 3139 df-rab 3142 df-v 3483 df-sbc 3759 df-dif 3922 df-un 3924 df-in 3926 df-ss 3935 df-nul 4275 df-if 4449 df-sn 4549 df-pr 4551 df-op 4555 df-br 5048 df-opab 5110 df-fr 5495 df-xp 5542 df-cnv 5544 df-dm 5546 df-rn 5547 df-res 5548 df-ima 5549 df-pred 6129 |
This theorem is referenced by: frmin 33086 |
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