  The Kadison-Singer problem asks: does every pure state on the diagonal
sublgebra of the C*-algebra of bounded operators on a separable infinite
dimensional Hilbert space admit a unique extension? A yes answer is equivalent
to several open conjectures including Feichtinger's: every bounded frame is a
finite union of Riesz sequences. We consider the special case: Feichtinger's
conjecture for exponentials and prove that the set of projections onto a
measurable subset of the circle group of the set of exponential functions
equals a union of a finite number of Reisz sequences if and only if there
exists a Reisz subsequence corresponding to integers whose characteristic
function is a nonzero minimal sequence.
