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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 8339 for more details on why this definition is desirable. Unlike df-rdg 8339 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 8332 and recsval 8333 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 8300 | . 2 class recs(𝐹) |
| 3 | con0 6311 | . . 3 class On | |
| 4 | cep 5522 | . . 3 class E | |
| 5 | 3, 4, 1 | cwrecs 8251 | . 2 class wrecs( E , On, 𝐹) |
| 6 | 2, 5 | wceq 1540 | 1 wff recs(𝐹) = wrecs( E , On, 𝐹) |
| Colors of variables: wff setvar class |
| This definition is referenced by: dfrecs3 8302 recseq 8303 nfrecs 8304 tfr1ALT 8329 tfr2ALT 8330 tfr3ALT 8331 csbrecsg 37301 |
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