! $!$
_|_ (   ) $\perp Xquad Xlangle Xquad XrangleS
V B SXforall Xquad Xexists S = SXneS
V d SXnabla Xquad Xpartial S ||xM SX! x X!S
a SXalphaS
= (mod 9) S Xequiv Xpmod{Xtheta}S
< SXleq S
1