CGAL users discussion list

[Winnie <>]

> The edges of a constrained Delaunay triangulation are in a superset of the
> constraint segments, and not in a subset.
Thank you, Laurent, for the hint! I got the "insight" while writing the 
reply below - so I still send it to the list in case anybody cares. ;-)



But wouldn't still be the constrained triangulation a special case for 
the decision problem?

constained triangulation
set of points P, constraints C \subseteq P^2
wanted: constrained triangulation T \subset P^2 such that C \subset T

Doesn't this implicitly solve the following decision problem?

set of points P, all edges E \subseteq P^2 that don't cross with edges 
from C (i.e. the constraints)
decide: is there a triangulation T \subseteq E

(... such that also C \subset T)



So no, they are not the same as C \subset T is important for the 
constrained triangulation. If there is a constrained triangulation, 
there clearly is a triangulation but if there is none you can't say 
anything about a triangulation in general.