We study the problem of deterministically predicting boolean values by
combining the boolean predictions of several experts. Previous on-lin
e algorithms for this problem predict with the weighted majority of th
e experts' predictions. These algorithms give each expert an exponenti
al weight beta(m) where beta is a constant in [0, 1) and m is the numb
er of mistakes made by the expert in the past. We show that it is bett
er to use sums of binomials as weights. In particular, we present a de
terministic algorithm using binomial weights that has a better worst c
ase mistake bound than the best deterministic algorithm using exponent
ial weights. The binomial weights naturally arise from a version space
argument. We also show how both exponential and binomial weighting sc
hemes can be used to make prediction algorithms robust against noise.