John Mc,

GEDmatch triangulation is probably closer to FTDNA "In common with". I'll give an example...

Say you run your kit "A" in the one-to-many utility and get 10 'matches'. I'll call the matches B1 through B10. When you run triangulation, it starts in the same manner, and ends up with 10 potential "triangulation groups". One for each of B1 through B10. The first group takes your kit "A" and kit "B1", and looks for any other kits that they both match, each one with at least one 7cM segment. If it finds such a kit (Call it B1.1), it shows how many cM it matches with both A and B1. then it does the same for any other kits it finds, B1.2 through B1.n where "n" is the total number of kits that match both "A" and B1. Then the same process is repeated for each triangulation group B2 through B10. And yes, you are right when you say that there is no guarantee that B1.1 through B1.n match each other.

To go beyond that and show how B1.1 through B1.n all match each other, and then B2.1 though B2.n, etc., all match each other, would take considerable resources - programming, CPU, and not to mention the amount of potential output it would generate. I'm not saying it couldn't be done, but I'm mostly concerned about my own workload. While I was typing this, my boss called and told me I have a new project, so that's even less available time for GEDmatch.

I spent some time this morning looking into what it would take to add checkboxes to the triangulation output to link results to a modified version of the 3D-Chromosome browser. It's probably doable, but would take some time. Doing something like that with an "A-matrix" might be easier for me. That would give an indication of a "match", but it wouldn't tell you which segment.

John O.