Joohyung Lee and Vladimir Lifschitz
An "additive" fluent is a fluent with numerical values such that the effect of several concurrently executed actions on it can be computed by adding the effects of the individual actions. We show how queries about additive fluents can be answered using the Causal Calculator. The examples discussed in this paper involve buying and selling, applying forces and moving groups of objects. The additive fluent mechanism can be used to instruct the Causal Calculator to generate more efficient plans.