Widening Operators for Weakly-Relational Numeric Abstractions (Extended   Abstract)
  We discuss the divergence problems recently identified in some extrapolation operators for weakly-relational numeric domains. We identify the cause of the divergences and point out that resorting to more concrete, syntactic domains can be avoided by researching suitable algorithms for the elimination of redundant constraints in the chosen representation. 
Roberto Bagnara, Patricia M. Hill, Elena Mazzi, and Enea Zaffanella