SHARPENED LOWER BOUNDS FOR CUT ELIMINATION.

We present sharpened lower bounds on the size of cut free proofs for first-order logic. Prior lower bounds for eliminating cuts from a proof established superexponential lower bounds as a stack of exponentials, with the height of the stack proportional to the maximum depth d of the formulas in the original proof. Our results remove the constant of proportionality, giving an exponential stack of height equal to d - O(1). The proof method is based on more efficiently expressing the Gentzen--Solovay cut formulas as low depth formulas. [ABSTRACT FROM AUTHOR]