1. A comparison engine for generating a ranked list of alternatives, the comparison engine comprising: a tradeoff module, executing on a computer, the tradeoff module having at least two tradeoff criteria, the at least two tradeoff criteria having a range of possible values, the tradeoff module being capable of receiving assigned values for the at least two tradeoff criteria, a criteria behavior module, the criteria behavior module being capable of analyzing predetermined attributes for a set of alternatives, where the attributes include values of the tradeoff criteria, the criteria behavior module being further capable of generating a set of scores reflecting desirability of the attributes using at least two logic diagrams, and a scoring and ranking module, the scoring and ranking module being capable of receiving the assigned values from the tradeoff module and the set of scores from the criteria behavior module and generating a ranked list of alternatives.