.nr PO 1i
.ND
.PP
Xmagic allows you to type in formulae in three places:
.IP 1 
in the "bad guy" window: this is the top right dialog box on the main control
panel;
.IP 2 
in the "define axiom" pop-up window: this window can be called from the
"add axioms" pop-up;
.IP 3 
in the "connectives" window.
.PP
The following conventions govern typing of formulae:
.IP a   
Variables are  'p', 'q', 'r', 's'.
Upper case will be converted to lower by the parser.
Any other letter will be treated as garbage.
.IP b   
Parentheses should be written in full, except that
.RS
.IP i 
outermost parentheses are unnecessary
.IP ii
all right parentheses are unnecessary
.IP iii
a period (".") is equivalent to "("
.RE
.IP
Because no scope rules are in force, association to 
the left is assumed.  Therefore the right mate of 
a left parenthesis immediately follows the shortest 
intervening formula with dyadic main connective.
For this reason right parentheses are redundant.
.IP c
Spaces are ignored.  RETURN terminates the formula.
.IP d
The connectives are "&" (ampersand), "v" (vee), 
"~" (tilde) and ">" (greater than).  Implication
may also be written as "->" (with optional minus).
Sentential constants "t" and "f" are also allowed.

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