Return to Revisions

2 of 3

edited body

edited Feb 23, 2011 at 11:27

Name for union of upsets/downsets

Set of lower bounds in poset is defined like $ A^l = \{ x \in P : \forall a \in A . x \le a \} = \bigcap_{a \in A} \{ x \in P : x \le a \}$.

Is there in literature a name for union $ \bigcup_{a \in A} \{ x \in P : x \le a \} $?

asked Feb 23, 2011 at 0:42