Up: The syntax of the
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Atomic terms of the language of Watson are of four kinds. All atomic
terms are represented by strings of nonzero length of alphanumeric
characters (Watson is case-sensitive) plus the special characters ? and _.
- A string consisting entirely of digits is a numeral.
- bound variables:
- A string consisting of a single ?
followed by a string of digits of nonzero length is a bound variable.
- free variables:
- A string beginning with ? which is not a
bound variable is a free variable (? by itself is a free
- A string beginning with a character other than ? and
containing at least one non-digit is a constant.