FOM: clarification

[Harvey Friedman]

Sorry, but I forgot to define the structure (A,SA,SSA,SSSA,...) in my two
postings of 4/1/99.

More generally, the structure (A_1,A_2,A_3,...), where the A_i are sets, is
the structure in the language of first order predicate caluclus with
infinitely many sorts, and with the epsilon relation between successive
sorts. NOTE: We don't have the epilson relation on any given sort.

Recall, I wrote:

Let
*) be:

there is a set A such that the relational structure with infinitely many
sorts, (A,SA,SSA,SSSA,...) is elementarily equivalent to (SA,SSA,SSSA,...)?