Why the Monkey Needs the Box: A Serious Look at a Toy Domain

“Toy worlds” involving actions, such as the Blocks World and the Monkey and Bananas domain, are often used by researchers in the areas of commonsense reasoning and planning to illustrate and test their ideas. Many of the axioms found in descriptions of these toy worlds are expressions of generalpurpose knowledge, though they are often cast in a form only useful for solving one specific problem and are not faithful representations of general facts that can be used in other domains. Instead of using such domain-specific axioms for each problem, we are building a general-purpose library of action descriptions which can be referred to in descriptions of action domains. The library is being written in the modular action description language MAD, an extension of the action language C+. In this paper we present an initial version of some of our library modules, along with a new formalization of the Monkey and Bananas domain that uses the library. Most of the axioms in this formalization come from the library, with only a few domainspecific axioms needed.