Syntax

COBA 2.0 accepts almost all alphanumerical strings for atom names. The exceptions are the symbols in the following comma-separated list: ', +, &, ^, ~, =, >, ( and ). Note that T and F stand for $\top$ and $\bot$, respectively.

More complex formulas can be constructed from fromulas A and B using connectives.

• ~A for the negation of A
• (A&B) for the conjunction of A and B
• (A+B) for the disjunction of A and B
• (A>B) for A implies B
• (A=B) for A is equivalent to B

A top-level formula with a binary connective (&, +, >, or =) must be enclosed in parentheses. Parentheses within a formula, however, are optional and are used only to enforce parsing preference. For example, (a&b+c) is a valid input sentence and is different from (a&(b+c)), whereas a top-level sentence like a&b is syntactically malformed.