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General Object-Level Rules
ABS.1: If the objects in C2 are very nearly the same, in shape and material properties,
as the objects in C1, then inferences made about C1 are probably valid in C2.
Any physical category, probabilistic, meta-level.
Comment: The unpublishable paper (Davis 1995) presents some classes of kinematic
inferences where this can be made deterministic.
ABS.2: If C1 involves a numerous collection of similar objects, and C2 involves a
similar collection with slightly fewer or more objects, then inferences made
about C1 are probably valid in C2.
Any physical category, probabilistic, meta-level.
ABS.3: The validity of any kinematic inference depends only on the parts of the object
boundaries that can come into contact.
Kinematic, deterministic, meta-level.
ABS.4: If a set of objects is tightly joined kinematically, then they can be treated
as a single object.
Any physical category, deterministic, collection of objects, abstraction.
ABS.5: If a set of objects is joined kinematically in a way that is nearly tight
(i.e. has very little play), and the play is very small as compared to any other
features of the scenario, then they can generally be treated as a single object.
However, the coefficient of restitution (elasticity) of the composite object
is typically smaller than in the component objects.
Any physical category, probablistic, abstraction.
ABS.6: If a set of objects is tightly jammed and the force needed to separate them is
large as compared to any of the forces generated in the scenario, then they can
generally be treated as a single object.
As regards theory level: establishing (or stating) the antecedent
requires statics. However, the conclusion can be applied to
inferences at any level. Probabilistic, abstraction.
ABS.7: In ABS.4, ABS.5, ABS.6 if any of the component objects is fixed then the composite
object is fixed.
Addendum to those various rules.
ABS.8: If an object is in a highly stable position and is very heavy as compared to any of the other objects or forces in the scenario, then it can generally be treated as a fixed object. As regards theory level: establishing (or stating) the antecedent requires statics. However, the conclusion can be applied to inferences at any level. Probabilistic, abstraction.
ABS.9: Let OM be a set of mobile objects. If the objects in OM do not come into
contact with any mobile objects during an interval, then the behavior of the objects
in OM during that interval depends only on the objects in OM and the fixed
objects they come into contact with.
Any theory level, deterministic, abstraction.