\documentclass[a4paper,10pt,twoside]{article} \usepackage{a4wide,amssymb,begriff} \title{Begriffsschrift examples} \author{Josh Parsons} \parindent0pt \setlength{\BGthickness}{1pt} \begin{document} \maketitle if p then q: $$\BGassert\BGconditional{p}{q}$$ and with a content stroke instead of assertion: $$f\BGbracket{\BGcontent\BGconditional{p}{q}}$$ from Frege's correspondence with Russell (a version of basic law V): $$ \BGassert (\acute{\epsilon}f(\epsilon) = \acute{\alpha}g(\alpha)) = \BGquant{\mathfrak{a}} \BGbracket{\BGconditional{ \BGnot\BGconditional{ \BGnot\mathfrak{a}=\acute{\alpha}g(\alpha) }{ \mathfrak{a}=\acute{\epsilon}f(\epsilon) } } {f(\mathfrak{a}) = g(\mathfrak{a})}} $$ \setlength{\BGlinewidth}{2.6in} from Russell's correspondence with Frege: $$ \BGstem{T=\acute{\beta}\acute{\gamma}} \BGnot\BGquant{\varphi} \BGconditional {\BGterm{\gamma = \acute{\alpha}\acute{\epsilon}\varphi(\alpha,\epsilon)}} {\BGconditional {\BGterm{\beta = \acute{\alpha}\acute{\epsilon}\varphi(\alpha,\epsilon)}} {\BGterm{\varphi(\beta,\gamma)}} } $$ the Geach-Kaplan sentence (thanks to Marcus Rossberg): $$ \BGnot \BGquant{\mathfrak{F}}% \BGconditional{ \BGquant{\mathfrak{c}}\BGquant{\mathfrak{d}} \BGconditional{ \BGnot \BGconditional{ \BGterm{A(\mathfrak{c},\mathfrak{d})} }{ \BGnot \BGterm{\mathfrak{F}(\mathfrak{c})}} }{ \BGnot \BGconditional{ \BGterm{\mathfrak{F}(\mathfrak{d})} }{ \BGterm{\mathfrak{c}=\mathfrak{d}} } } }{ \BGconditional{ \BGnot\BGquant{\mathfrak{b}}\BGnot\BGterm{\mathfrak{F}(\mathfrak{b})} }{ \BGterm{f \BGbracket{\BGquant{\mathfrak{a}} \BGconditional{ \mathfrak{F}(\mathfrak{a}) }{ C(\mathfrak{a}) }}} } } $$ That's all folks \end{document}