Maybe thinking of Heegner (https://en.wikipedia.org/wiki/Kurt_Heegner)? I give this example (that I learned from a book of van der Poorten) in my Inference piece.
"An order on the set of finite rooted trees is defined recursively: we first order the subtrees joined to the root in decreasing order, and then use lexicographic order on these ordered sequences of subtrees. In this…
Author here :-) There's two layers to it, and you've described the first one. The argument you give about tuples of non-negative integers is what implies the consistency of PRA or Primitive Recursive Arithmetic…
Maybe thinking of Heegner (https://en.wikipedia.org/wiki/Kurt_Heegner)? I give this example (that I learned from a book of van der Poorten) in my Inference piece.
"An order on the set of finite rooted trees is defined recursively: we first order the subtrees joined to the root in decreasing order, and then use lexicographic order on these ordered sequences of subtrees. In this…
Author here :-) There's two layers to it, and you've described the first one. The argument you give about tuples of non-negative integers is what implies the consistency of PRA or Primitive Recursive Arithmetic…