4
$\begingroup$

Can someone tell me what this symbol means?

$\bigsqcup$

  • 13
    It would be *extremely* helpful if you tell us where you saw it. This is like asking what does the symbol $\partial$ means. It may have different meanings in different contexts.2012-08-03
  • 3
    It's usually some generalization or specialization of the "union" sign, but it does greatly depend on context.2012-08-03
  • 13
    My default interpretation is of disjoint union, thought it's also similar to the symbol often used coproducts.2012-08-03
  • 3
    [Search results for `\bigsqcup` on math.SE](http://math.stackexchange.com/search?q=%5Cbigsqcup).2012-08-03
  • 0
    @Andrew: disjoint union is a coproduct. I'd say it is almost certainly some coproduct. In what category, it would depend on the context.2012-08-03
  • 0
    I simply meant that, though $\amalg$ seems to be the most common notation for general coproducts (not necessarily of sets), $\bigsqcup$ might have been used instead.2012-08-03
  • 8
    I think it tells you where to put the staple.2012-08-03
  • 0
    $\bigsqcup A$ is also used to denote (if existent) the smallest upper bound of a given subset $A \subseteq X$ of a partial ordering $(X, \le)$, but now that I think of it, this may also be viewed as a coproduct... Sorry.2014-06-17

2 Answers 2