THE RUINOUS-THIN RELATIONSHIP FOR THREE ELEMENT SETS.

Richard Thompson's group F is nonamenable if and only if there exists a ruinous set. It is known that no three element set is ruinous. Here we explicitly construct a family of thin sets for any three element set each of whose trees has three carets. We then show where this construction fails when each of the trees has four or more carets. [ABSTRACT FROM AUTHOR]