The symbol , used for the intersection
of sets, and sometimes also for the logical connective AND
instead of the symbol
(wedge). In fact, for any two sets and
and this equivalence demonstrates the connection between the set-theoretical and the logical meaning.
The term "cap" is also used to refer to the topological object produced by puncturing a surface a single time, attaching two zips
around the puncture in opposite directions, distorting the hole so that the zips
line up, and then zipping up. The cap is topologically trivial in the sense that
a surface with a cap is topologically equivalent to a surface without one.
, used for the intersection
of sets, and sometimes also for the logical connective AND
instead of the symbol 
(wedge). In fact, for any two sets 
and 
