So there's \in, \subseteq and probably many others that are written just like in Latex. Notably \cap and \cup were also copied from Latex, which describe the shape of the symbol instead of its meaning. But not \to, \mapsto, \Vee and \Wedge, they're written as ASCII art ->, |->, \/ and /\.
Then there's SUBSET, which means power set ... yeah. -_-
Then there's SUBSET, which means power set ... yeah. -_-