How can I find ‘inner’ edges for example of a triangle strip.
I thought about the number of the incoming edges of both endpoints of the edge in question. If this number is greater than 2 then the edge cannot be a border edge. But how can I create a group which just contains edges which are enclosed by other edges ? Group with edge depth didnt work ( no clue why )
In the example image I would like to select the edges connecting points 1,2 and 1,4. Not the surounding edges of this little strip.

any help appreciated

No idea really, but you can get the inverse of what you're looking for with the “Remove Shared Edges” option in the Divide SOP. For what it's worth..

I had a new Idea to solve this problem. I could split the triangles with edgecusp and later group all edges which consist of points which share identical positions, which would be reduced by the clean node / consolidate points.
But how can I select/group those edges ??

What would be the houdini way to merge 2 triangles into one quad ?
I created a VOP SOP which finds the Points with more than 2 adjacencys connected to a neighbour with the same or more adjacencys. those pairs of point are the edges I want to dissolve, but how do I get edges out of this vop sop ? I also was not able to create a group of edges .. how is this done ?
If I dissolve points with the notation p1-4 one of my unwanted edges is dissolved, but if I create a group with the same notation and try to dissolve this group it doesnt work.

Solved the problem, but there has to be a better way of doing things.
Maybe someone can point me in a more elegant direction.

At the moment I create some attributes in VopSop context :
adjacency count and the first two adjacences.

Then i use a python script in the group parameter to generate those px-y strings.

The whole thing has the purpose of optimizing 3d coat meshes which consist mostly of quads but also some ngons. the ngons shall be trippled in houdini and those triangles shall be merged again into quads to just leave as little triangles as possible.