A surprising Python quirk
willmcgugan.comNothing surprising about this if you know grade school math. Nor is it really about Python at all.
The empty set is a subset of every set.
Are strings sets?
Analogously, the empty net is a subnet of every net, the empty sequence is a subsequence of every sequence etc etc.
Also, [p implies q] is vacuously true if p is false.
Strings are maps from nonnegative integers to the space of characters. You can think of them as sets of ordered pairs or sequences.