I am using pdfLaTeX from TeXLive on Kubuntu 20.04. Suppose that the LaTeX document I am writing is entirely in U.S. English.
How can I use the usenglishmax hyphenation patterns (which are mentioned at the end of this) from hyph-utf8? Does one use it in conjunction with hyphsubst? Does one need to use babel, even if the entire text is in U.S. English?
I find the documentation quite unclear.
In particular, is the following the correct usage?
(This is adapted from the Speravir's comments to this answer.)
\documentclass[10pt]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{hyphsubst}
\HyphSubstIfExists{hyph-en-us}{\HyphSubstLet{english}{hyph-en-us}}{}
\usepackage[english]{babel}
\usepackage{testhyphens}
\begin{document}
% just for testing purposes, let's set these to zero
\lefthyphenmin=0
\righthyphenmin=0
% must be done after \begin{document}, because it seems 'babel'
% sets these at that point
%
% The defaults for U.S. English are
% \lefthyphenmin=2 and \righthyphenmin=3
\thispagestyle{empty}
% testing on the first ten entries from the
% 2021 version of ushyphex.tex
% (https://ctan.org/pkg/hyphenex)
\begin{checkhyphens}{}
academy academies accusative acronym acronyms
acupuncture acupuncturist adamant addable addible
\end{checkhyphens}
\end{document}
Lastly, on what words can I test it (say, using the package testhyphens)? In other words, what are some words that get hyphenated with usenglishmax that are not hyphenated in a LaTeX document that doesn't use usenglishmax?
For what it's worth, in the example above, all ten words get hyphenated that same regardless of whether the lines
\usepackage{hyphsubst}
\HyphSubstIfExists{hyph-en-us}{\HyphSubstLet{english}{hyph-en-us}}{}
are commented out or not.
On the other hand, if the line \usepackage[english]{babel} is also commented out, then some of the words get hyphenated differently.
Appendix:
Best Answer
You want to change the language name; mentioning the hyphenation pattern file is useless.
If I comment the substitution line, I get
Thus you see that new patterns are used. Still, you're not guaranteed to get everything is in the hyphenation exception list
ushyphex.tex.With
one gets