frege.sty - a LaTeX2e package for typesetting begriffsschrift

This package is based on begriff.sty released under the GNU General Public License. 
Copyright (C) 2003 by Josh Parsons

Since version 1.3 this package also makes use of the bguq package by J.J. Green.

Changes with respect to begriff.sty

correct relative lengths of the content stroke with respect to other strokes 
attached to it;
content strokes point at the middle of the following symbols, rather than the bottom;
greater width for the assertion stroke as compared to the content stroke;
a more intuitive structure for the conditional (arguments are now given in the same 
order as they appear on the left of a completed formula);
the command for the conditional with empty arguments now results in a vertical line 
(conditional stroke) on it's own the other strokes are added as the arguments;
the linewidth is properly accounted for so that things remain properly centered when 
scaled;

frege.sty defines the following basic commands:
\Fcontent[1]       - plain content stroke
\Fncontent[1]      - negated content stroke
\Fnncontent[1]     - twice negated content stroke
\Faconten[1]       - asserted content stroke
\Fancontent[1]     - asserted negated content stroke
\Fanncontent[1]    - asserted twice negated content stroke
\Fquant[1]{a}      - content stroke with quantifier
\Fnquant[1]{a}     - negated quantifier
\Fnnquant[1]{a}    - twice negated quantifier
\Fquantn[1]{a}     - quantifier with negated content
\Fquantnn[1]{a}    - quantifier with twice negated content
\Fnquantn[1]{a}    - negated quantifier with negated content
\Fnquantnn[1]{a}   - negated quantifier with twice negated content
\Fnnquantn[1]{a}   - twice negated quantifier with negated content
\Fnnquantnn[1]{a}  - twice negated quantifier with twice negated content
\Faquant[1]{a}     - asserted content stroke with quantifier
\Fanquant[1]{a}    - asserted negated quantifier
\Fannquant[1]{a}   - asserted twice negated quantifier
\Faquantn[1]{a}    - asserted quantifier with negated content
\Faquantnn[1]{a}   - asserted quantifier with twice negated content
\Fanquantn[1]{a}   - asserted negated quantifier with negated content
\Fanquantnn[1]{a}  - asserted negated quantifier with twice negated content
\Fannquantn[1]{a}  - asserted twice negated quantifier with negated content
\Fannquantnn[1]{a} - asserted twice negated quantifier with twice negated content

while this may look like a daunting list think of it as just two commands:
\Fcontent[1]       - generates a content stroke
\Fquant[1]{a}      - generates a quantifier with variable a

Adding an "a" after the "\F" adds an assertion stroke to the front of the command, 
this may be followed by one two or no "n" to add one two or no negations to the 
stroke. Next comes the name of the command either "content" or "quant". "quant" may 
then be followed by another one two or no "n" which will add one two or no negations 
after the quantifier to it's content stroke. All commands may be used in either text 
or math mode. All the above commands produce output of the same length and may be 
arbitrarly combined to produce longer composite formulas. Since version 1.1 each of 
the basic strokes also has an optional argument with default value one, that scales 
the total length of the stroke (\Fbaselength), so that an optional argument of [.5] 
will produce a stroke half as long. Warning: setting a length shorter than what is 
needed to fit all the options of a stroke leads to negative lengths and hence 
unpredictable results.

Since version 1.3 it is also possible to call all the above commands without the 
word "content" for the content strokes and with just "q" instead of the word "quant" 
for the quantifiers.

frege.sty defines the following more complex commands:
\Fconditional[<option>]{<consequent>}{<antecedent>}
\Fbox{<begriffsschrift formula with at least one conditional>}
\Fbracket{<begriffsschrift formula with at least one conditional>}
\Fargument[<premise 0>]{<premise 1>}{<premise 2>}{<conclusion>}
\Fstrut[1]

The final two have been added in version 1.2.

The following shorthands for the above commands have been introduced in version 1.3: 
\Fcdt, \Fb, \Fbb, \Farg, \Fs;

The "Fconditional" command requires a mixture of the commands defined by frege.sty 
and normal mathmode input to produce begriffsschrift. A implies B would be written 
like this: 

\Fconditional[\Facontent]{\Fcontent B}{\Fcontent A}

This produces the two dimensional fregean conditional symbol with B lined up above 
A. In addition the "Fconditional" command may be arbitrarily nested to produce any 
begriffsschrift formula possible. All begriffsschrift symbol can be made without 
the use of the optional argument, it exists only for convenience.

"Fbracket" is just the same as "\left(\Fbox\right)" everything said about "Fbox" 
applies equally to "Fbracket". A completed formula of begriffsschrift that includes 
at least one conditional, should always be placed in an "Fbox" this ensures it is 
given enough space in the output behaves correctly with respect to the text around 
it and works correctly within environments such as align*.

"Fargument" arranges two begriffsschrift formulas above each other and seperates 
them from a third by a horizontal line. The option is for the name of a premise 
written elsewhere and will outout (name): to the left of the horizontal line.

"Fstrut" is like a invisible content stroke. Like all other basic strokes, it may be 
scaled using it's optional argument. Fstrut is to be used in conjunction with 
Fargument to ensure the formulas line up properly.

The final result may also be modified by changing the following lengths using the 
\setlength{<lengthname>}{<value>} command. The lengths and there default values are 
given as follows:

length:         default value:  description:
\Fbaselength    20pt            the length of a single basic stroke
\Flinewidth     0.5pt           the width of all lines other than the assert stroke
\Fspace         2pt             seperation between begriffsschrift and text/formula
\Fassertwidth   3\Flinewidth    the width of the assert stroke
\Fraiseheight   1ex-\Flinewidth the height of content strokes above the baseline
\Fnegsep        3\Flinewidth    the sepparation between a double negation
\Fnegshort      2\Flinewidth    the space between negation stroke and baseline
\Fquantwidth    6pt             width of the semi circular quantifier depression

Since version 1.3 it is possible to load this package using the "bguq" option: 
\usepackage[bguq]{frege}

if the bguq option is enabled all quantifiers will use the bguq character provided 
by the bguq package by J.J. Green rather than the qbezier used by this package. 
This means the bguq package must be installed to use the option. (It can be found 
on ctan: http://www.ctan.org/pkg/bguq).
Warning: as it stands the bguq character scales with font while the rest of the 
symbols provided by this package do not. Also, the bguq character will not respond 
to a change in Flinewidth.

For more examples and info see accompanying manual (frege.pdf or frege.tex)
Everything released under GNU General Public License.