4 ms·
I mean it's literally the same idea as in set theory. phi is an empty set, (phi) is a set containing an empty set ((phi)) is a set containing a set containin
by dhanvanthri 5y ago
I mean it's literally the same idea as in set theory.
phi is an empty set,
(phi) is a set containing an empty set
((phi)) is a set containing a set containing an empty set
Furthermore, it's one of the only syntax rules; if it's not a list, then the first element is an operator/function.
- Rerarom 5y agoI agree with that, but in set theory the symbol {} is used. I have nothing against it, I just think it should be emphasized more.
- Koshkin 5y agoHmm, never thought of ∅ as a φ. (According to Wikipedia, the symbol was introduced in the 1930s by Weil, inspired by the letter Ø in the Danish and Norwegian alphabets.)