### WELL FORMED FORMULA

How to represent English statements in sentential logic. Sentential logic is made up of three elements:

- Simple atomic propositions represented by a single capital letter (A...Z).
- Five logical connectives: (negation, implication, disjunction, conjunction, and equivalence).
- Marks of punctuation (parenthesis, brackets, and braces.)

Definition:

- Every simple, atomic proposition is a wff; (A), (B), (C)... are wff.
- Compound, molecular propositions:if A is a wff then ~A is a wff. if A is a wff and B is a wff, then (A.B), (A+B), (A>B), and (A=B) are all wff.
- The five logical connectives and the three marks of punctuation allow you to string together compound, molecular propositions from simpler ones.
- Each compound proposition has two or more components (sub-expressions) and a main logical connective.
- If ~A is a wff then A is the only component and '~' is the main logical connective.
- If (A.B), (A+B), (A>B), and (A=B) are wff, then A is the left component and B is the right component. And '.', '+', '>', and '=' are their respective logical connectives.

Kinds of propositions:
simple (atomic):
A
Z
negation:
~(A>B)
~[(B>C)>F]
conjunction:
(A.B)
[(X>B).(D>O)]
disjunction:
(A+B)
[(U>T)+(H>B)]
implication:
(A>B)
[(C+O)>K]
equivalence:
(A=B)
[(S>N)=(X.V)]