Matrix subsets of arbitrary dimension

["Paul, David A" <paulda@BATTELLE.ORG>]

Searching the S-news archive revealed a suggestion by John Fox to use

        mat[is.element(mat[,1],2*1:5),]

as a way of obtaining a matrix subset of a priori unknown dimensions when
one knows the values one wishes to match.  Can anyone suggest a method to 
use when one knows the values one *does not* wish to match?  My goal is
to be able to obtain dataframe or matrix subsets based on excluding rows
that
have undesirable values in them.

 David Paul, Ph.D.
  Battelle Memorial Institute
  505 King Avenue
  Columbus, OH  43201
  614.424.3176