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| Mirrors > Home > MPE Home > Th. List > df-recs | Structured version Visualization version GIF version | ||
| Description: Define a function recs(𝐹) on On, the class of ordinal numbers, by transfinite recursion given a rule 𝐹 which sets the next value given all values so far. See df-rdg 8338 for more details on why this definition is desirable. Unlike df-rdg 8338 which restricts the update rule to use only the previous value, this version allows the update rule to use all previous values, which is why it is described as "strong", although it is actually more primitive. See recsfnon 8331 and recsval 8332 for the primary contract of this definition. (Contributed by Stefan O'Rear, 18-Jan-2015.) (Revised by Scott Fenton, 3-Aug-2020.) |
| Ref | Expression |
|---|---|
| df-recs | ⊢ recs(𝐹) = wrecs( E , On, 𝐹) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | cF | . . 3 class 𝐹 | |
| 2 | 1 | crecs 8299 | . 2 class recs(𝐹) |
| 3 | con0 6312 | . . 3 class On | |
| 4 | cep 5519 | . . 3 class E | |
| 5 | 3, 4, 1 | cwrecs 8250 | . 2 class wrecs( E , On, 𝐹) |
| 6 | 2, 5 | wceq 1542 | 1 wff recs(𝐹) = wrecs( E , On, 𝐹) |
| Colors of variables: wff setvar class |
| This definition is referenced by: dfrecs3 8301 recseq 8302 nfrecs 8303 tfr1ALT 8328 tfr2ALT 8329 tfr3ALT 8330 csbrecsg 37632 |
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