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Atomic Terms

These fall into four categories:

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.

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