The Naive Physics Perplex

ion in physical reasoning. Approximation and abstraction in physical reasoning takes many forms: Objects of complex characteristics can be approximated by objects of simpler characteristics (for example, a real resistor by an ideal resistor or a curved object by a polyhedral object), a group of objects can be approximated by a single object (figure 10), and a group of simple objects can be approximated by a single complex object (for example, a chain of rigid links by a string). The case where a complex microworld is approximated by a simpler microworld is just one of many Articles 76 AI MAGAZINE approximates in special cases add constraints