Any point in " HP " is an infinite distance from the point " p " at the foot of the perpendicular to " R ", but a sequence of points on this perpendicular may tend in the direction of " p ".
22.
The family of sequences of removals that can be formed in this way is the shelling antimatroid of the point set, and the set of edges of convex hulls of the sequence of point sets formed by this removal process forms a pseudotriangulation.
23.
The stack technique used in Graham's scan is very similar to that for the all nearest smaller values problem, and parallel algorithms for all nearest smaller values may also be used ( like Graham's scan ) to compute convex hulls of sorted sequences of points efficiently.
24.
Roughly speaking, a function is upper hemicontinuous when ( 1 ) a convergent sequence of points in the domain maps to a sequence of sets in the range which ( 2 ) contain another convergent sequence, then the image of limiting point in the domain must contain the limit of the sequence in the range.
25.
If ( " a " " n " ) is a sequence of points in a metric space, then the formula can be used to define convergence, if the expression | a _ n-L | is replaced by the expression \ text { dist } ( a _ n, L ), which denotes the distance between a _ n and L.
26.
Although for Leibniz the situs of a sequence of points is completely determined by the distance between them and is altered if those distances are altered, his admirer Euler, in the famous 1736 paper solving the K�nigsberg Bridge Problem and its generalizations, used the term " geometria situs " in such a sense that the situs remains unchanged under topological deformations.
