display all the ideas for this combination of texts
4 ideas
17752 | The empty set is useful for defining sets by properties, when the members are not yet known [Walicki] |
17753 | The empty set avoids having to take special precautions in case members vanish [Walicki] |
21717 | Reducibility undermines type ramification, and is committed to the existence of functions [Quine, by Linsky,B] |
17759 | Ordinals play the central role in set theory, providing the model of well-ordering [Walicki] |