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Mirrors > Home > MPE Home > Th. List > Mathboxes > df-hf | Structured version Visualization version GIF version |
Description: Define the hereditarily finite sets. These are the finite sets whose elements are finite, and so forth. (Contributed by Scott Fenton, 9-Jul-2015.) |
Ref | Expression |
---|---|
df-hf | ⊢ Hf = ∪ (𝑅1 “ ω) |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | chf 34401 | . 2 class Hf | |
2 | cr1 9451 | . . . 4 class 𝑅1 | |
3 | com 7687 | . . . 4 class ω | |
4 | 2, 3 | cima 5583 | . . 3 class (𝑅1 “ ω) |
5 | 4 | cuni 4836 | . 2 class ∪ (𝑅1 “ ω) |
6 | 1, 5 | wceq 1539 | 1 wff Hf = ∪ (𝑅1 “ ω) |
Colors of variables: wff setvar class |
This definition is referenced by: elhf 34403 |
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