Journal article:
Samuel R. Buss and Toniann Pitassi.
"Good Degree Bounds on Nullstellensatz Refutations of the
Induction Principle."
Journal of Computer and System Sciences 57 (1998) 162-171.
Download article: postscript or PDF.
Abstract: This paper gives nearly optimal, logarithmic upper and lower bounds on the minimum degree of Nullstellensatz refutations (i.e., polynomials) of the propositional induction principle.
Earlier conference version:
Samuel R. Buss and Toniann Pitassi.
"Good Degree Bounds on Nullstellensatz Refutations of the
Induction Principle."
in Complexity '96, Proceedings of the Eleventh Annual
IEEE Conference on Computational Complexity, 1996, pp 233-242.
Conference version not available for download here.