Command \algorithmic already defined

Question

Here is the list of packages I load for my presentation:

\documentclass{beamer}
\usepackage[frenchb]{babel}
\usepackage[utf8]{inputenc}
\usepackage[T1]{fontenc}
\usepackage{stmaryrd}
\usepackage{amsthm}
\usepackage{color}
\usepackage{mathtools}
\usepackage{tikz}
\usepackage[boxed]{algorithm2e}
\usepackage{algorithmic}
\usepackage[parfill]{parskip}
\usepackage{stmaryrd}
\usepackage{caption}
\usepackage{amssymb}
\usepackage{amsfonts}
\usepackage{bbm}
\usepackage{bm}
\usepackage{empheq}
\usepackage{framed}
\usepackage{mathbbol}
\usepackage{float}
\usepackage{caption,subcaption}%
\usepackage{calc}% http://ctan.org/pkg/calc
\usepackage{hyperref}
\usepackage{multicol}
\usepackage{environ}
\usetikzlibrary{positioning,shapes,shadows,arrows,shapes.multipart}

There are 4 packages (as follows) that I use for my article, but if I add them to the list, it gives me an error Command \algorithmic already defined. I guess some packages are not compatible with the one above:

\usepackage{algpseudocode}
\usepackage[all]{xy}
\usepackage{longtable}
\usepackage{listings,xcolor,lipsum}

Without loading the 4 packages, one problem is that a formula like abc_\textbf{index} which works in my article does not work anymore, so I need to change it to abc_{\textbf{index}}. And I have a lot of formulae having that...

So could anyone tell me which package is relevant to that? and how to add it to the list for my presentation?

Thank you very much!

Answer 1

algpseudocode (as part of the algorithmicx package) defines an algorithmic environment, and is therefore not compatible. That is, algorithmicx.sty defines the algorithmic environment using

\newenvironment{algorithmic}[1][0]%
  {...}

Specifying the package option

\usepackage[algcompatible]{algpseudocode}

only allows for compatibility with the former algorithmic package notation. That is, commands like \REQUIRE, \ENSURE, \STATE and \COMMENT are directed to imply \item[\algorithmicrequire], \item[\algorithmicensure], \State and \Comment under algorithmicx. Regardless, you are not able to use both algorithmic and algorithmicx in your document preamble.

The beamer document class does not enjoy abc_\textbf{index}, while the article document class doesn't complain. I'm guessing there might be something internally done by beamer that modifies the regular usage. If this is problematic, I'm sure you could use something like sed to parse your existing .tex document and replace all occurrences of <stuff>_<sub-stuff> with <stuff>_{<sub-stuff>}. Regardless, if this is a restriction in beamer, it may be useful to embrace it, both literally and figuratively.