1. The problem statement, all variables and given/known data One way of modeling tuples in set theory is through nested ordered pairs. A notation I'm not familiar with (I'm assuming it means that the following elements are nested into the last one) is used. (a1, a2, a2,... an) = (a1(a2, a3,..., an)). I have never seen the second "(" in the latter part of the equation. My question is what is a nested ordered pair? What are its properties? How can the second element in the latter part of the equation, have lots of elements; while, the whole thing still be an ordered pair? Nested generally means something in something, and an ordered pair is a couple or two tuple, but I can't seem to put the two together. 2. Relevant equations None that I know of 3. The attempt at a solution I've spent about 30 minutes searching and I still can't find a definition.