# F_d versus F_{d+1}

**Problem**Find a constant such that for any there is a sequence of tautologies of depth that have polynomial (or quasi-polynomial) size proofs in depth Frege system but requires exponential size proofs.

Problem statement from link.

Such tautologies are known if may depend on (for ). This problem is also closely related to conservativity relations among bounded arithmetic theories.

## Bibliography

*[K1] J.Krajicek: "Lower Bounds to the Size of Constant-Depth Propositional Proofs", J. of Symbolic Logic, 59(1), (1994), pp.73-86

[K2] J. Krajicek: "Bounded arithmetic, propositional logic, and complexity theory", Encyclopedia of Mathematics and Its Applications, Vol.60, Cambridge University Press, Cambridge - New York - Melbourne, (1995), 343 p. (on page 243)

* indicates original appearance(s) of problem.