# Complex Highlighting/Graying in Beamer

I have a Beamer slide in which I would like to emphasize different things sequentially. Here is my MWE:

\documentclass[t,serif,mathserif,professionalfont]{beamer} %

\setbeamercovered{invisible}
\setbeamercovered{%
again covered={\opaqueness<1->{40}}}

\mode<presentation>

\usepackage{amsmath}
\usepackage{amssymb}

\begin{document}

\begin{frame}\frametitle{A Title Here}
\begin{itemize}[<+>]
\item A first item describing some things
\item A second item leading to these equations: \par
\begin{center}
\large \vskip -.6cm
\begin{align}
{\color<3>{blue} F_m = F_{m-1} + F_{m-1}, \;\; m \in \mathbb{N}} \tag{Eq 1} \\
{\color<4>{blue} a^n + b^n = c^n, \;\; n \in \mathbb{N}\; \& \; a,b,c \in \mathbb{Z}} \tag{Eq 2}
\end{align}
\end{center}
\item With $F_0=0$ and $F_1=1$, this is Fibonacci's Sequence.
\item This is Fermat's last theorem.
\end{itemize}
\end{frame}
\end{document}


which creates a single slide with three pages.

I specifically want Eq 1 and then Eq 2 to turn blue when the third and fourth items appear, AND I want Eq 2 to be grayed when the third item appears, and Eq 1 to be grayed when the fourth item appears.

The problem is when Eqs 1 or 2 turn blue, they are still grayed. Is there any way to remove the gray for a single element of this sequence of three slides?

If you don't mind to abandon the automatic covering done by itemize, you could do:

\documentclass[t]{beamer}

\usefonttheme[onlymath]{serif}
\usefonttheme{professionalfonts}

\setbeamercovered{invisible}
\setbeamercovered{%
again covered={\opaqueness<1->{40}}}

\mode<presentation>

\usepackage{amsmath}
\usepackage{amssymb}

\begin{document}

\begin{frame}\frametitle{A Title Here}
\begin{itemize}
\item<1> A first item describing some things
\item<2-4> A second item leading to these equations:
\onslide<3-4>{%
\begin{center}
\large \vskip -.6cm
\begin{align}
{\color<3>{blue}\color<4>{gray}F_m = F_{m-1} + F_{m-1}, \;\; m \in \mathbb{N}} \tag{Eq 1}\\
{\color<4>{blue}\color<3>{gray} a^n + b^n = c^n, \;\; n \in \mathbb{N}\; \& \; a,b,c \in \mathbb{Z}} \tag{Eq 2}
\end{align}
\end{center}
}
\item<3-> With $F_0=0$ and $F_1=1$, this is Fibonacci's Sequence.
\item<4-> This is Fermat's last theorem.
\end{itemize}
\end{frame}
\end{document}


As you might have noticed I replaced some beamer options with

\usefonttheme[onlymath]{serif}
\usefonttheme{professionalfonts}


as the beamer options are obsolete.

• This doesn't actually answer the question but (+1) for effort. It is very, very hard to make Beamer do what the OP wants, it seems! You could get closer by changing 5 and 6 to 3 and 4 but the greying out of the equations still wouldn't meet the desiderata. – cfr Aug 25 '16 at 23:07
• @cfr Thanks for your comment! After reading the question again (and then a few more times, it is quite late here :) I changed the answer a bit. I hope this is closer to what the OP has in mind - however it would have been nice to get some feedback from the OP :( – samcarter_is_at_topanswers.xyz Aug 25 '16 at 23:39
• I think that is closer, yes. At least as I understand it. I can't upvote again, though! – cfr Aug 25 '16 at 23:56