28 ;;Quote: could test identity in terms of propagation of effects; doesn't work under inheritance or derivation rules

28 ;;Quote: the extensional set constructor is the ultimate test of identity; cardinality of the set is one

28 ;;Quote: durability (preserved under change) and distinguishability are important aspects of identity

28+;;Quote: questioning the equivalence of objects is really questioning references to objects

29 ;;Quote: an object identifier is a data value that reliably refers to an object, a surrogate

29 ;;Quote: represent an object's properties by associating its identifier with property values

29 ;;Quote: a computation system contains tokens that are occurrences of symbols outside the system; equivalent if symbols equivalent

29 ;;Quote: symbols are everything outside of the system that could have an occurrence inside the system; fixed set, e.g., the English alphabet, 1, x, the American flag

29 ;;Quote: the essence of change in a computational system is the appearance and disappearance of tokens of external symbols

30 ;;Quote: a handle is a symbol that is a surrogate for a thing; a reference is an occurrence of a handle; can be 1:1

30 ;;Quote: symbols have multiple, complex meanings and denotations, often varying from one context to another

31 ;;Quote: whether a symbol is one of the handles of some object, depends on the current scope; the denoted object may change with scope

32 ;;Quote: a computational system expresses awareness of things (via tokens or references), rather than the existence of things

32 ;;Quote: symbols that are valid handles to objects in most scopes are typically recognized syntactically, e.g., numbers, symbols, and strings

33 ;;Quote: an intensional set is a carrier object, i.e., an object with a persistent identity or name and a mutable content (cargo or extension)

36 ;;Quote: an object is an arbitrary set of things, which may or may not be in the computational system

36 ;;Quote: non-literal handles to objects are established by creation operations in some scope