The following set of ``situation calculus'' axioms solves the frame problem for a blocks world in which blocks can be moved and painted. Here result(e,s) denotes the situation that results when event e occurs in situation s. The formalism is approximately that of (McCarthy and Hayes 1969).
Objects change their locations and colors only for a reason.
Objects change their locations when moved and their colors when painted.
This prevents the rule (36) from being used to infer that an object will move if its top isn't clear or to a destination that isn't clear or if the object is too heavy. An object also cannot be moved to its own top.
A location is clear if all the objects there are trivial, e.g. a speck of dust.
Trivial objects are abnormal in aspect5.