I am building a presentation using Beamer and the Fitch Natural Deduction package by Selinger.
I am trying to use the \onslide command. For some reason it doesn't work when I follow the syntax and use a parenthesis afterwards {}, but if I just write it as is. Here is a code I found that works:
\documentclass[10pt,pdf]{beamer}
\usepackage{fitch}
\usepackage{amssymb}
\begin{document}
\begin{frame}
\frametitle {Working}
\[
\begin{nd}
\have {1} {p \rightarrow q} \by {premise} {}
\open
\onslide<3-> \hypo {2} {\neg q}
\open
\onslide<5-> \hypo {3} {p}
\onslide<6-> \have {a} {p \rightarrow q} \r{1}
\onslide<7-> \have {4} {q} \ie{3,a}
\onslide<8-> \have {5} {q \wedge \neg q} \ai{2,4}
\onslide<9-> \have {6} {\bot}
\close
\onslide<4-> \have {8} {\neg p} \ni {3-6}
\close
\onslide<2-> \have {9} {\neg q \rightarrow \neg p} \pause \ii{2-8}
\end{nd}
\]
\end{frame}
\end{document}
A problem I am facing is the inability to use the \onslide<+->, meaing with the plus sign. Meaning if I change the onslide from 6 onwards - it doesn't show the lines in the order I want to, meaing instead of: \onslide<6-> \have {a} {p \rightarrow q} \r{1}
write this: \onslide<+-> \have {a} {p \rightarrow q} \r{1}
and so on with 7, 8, 9 - when complied the order changes completely.
Thank you for your help.