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Atomic Terms

These fall into four categories:

numerals:
0 and non-zero-initial strings of digits. Subsumed under constants for most purposes in this document; the main difference is that numerals are predeclared.

constants:
Strings consisting of characters from the set consisting of the letters (upper and lower case are allowed and distinct), digits, and the characters _ and ?. A numeral is not a constant, and a constant may not begin with ?. Numerals are subsumed under constants in most respects, except that they are predeclared.

free variables:
As constants, except that they begin with ? and should contain in addition some non-digit.

bound variables:
A nonzero numeral prefixed with a ? is a bound variable.



Randall Holmes
Fri Sep 5 16:28:58 MDT 1997