Talk:Half-disk topology

Something's wrong here
From the article: "These extra sets are of the form {(x,0)} ∪ {P ∩ L}, where (x,0) is a point on the line L and U is an open, with respect to the Euclidean metric topology, neighbourhood of (x,y) in the plane."

Now there's no U in the formula; moreover P ∩ L is the empty set, therefore I guess one of them should have been an U (but I have no idea which one).

Actually the whole article is in need of a rework (I don't really know what to make of the initial section), but the most important part is to have the definition of the space correct. --93.135.132.140 (talk) 15:48, 16 September 2012 (UTC)