Cfrgtkky

The following code

documentclass{amsart}

usepackage[utf8]{inputenc}

usepackage[T1]{fontenc}

usepackage{eulerpx,bm}



begin{document}



$a<bquadbm{a<b}$



end{document}

Provides the following output:

The inequality symbol is not changed when I use, say, newpxmath instead. The problem seems to be indeed with the eulerpx package. How can this be solved?

Not sure what all this breaks, but I redefined a symbol font and made < active inside of bm.

The begingroup...endgroup isolates the catcode change, while still allowing binary operators inside the bm to see what is outside of the bm, shown in the MWE as ybm{-y}.

documentclass{amsart}

usepackage[utf8]{inputenc}

usepackage[T1]{fontenc}

usepackage{eulerpx,bm}

SetSymbolFont{letters}{bold}    {U}{zeur}{m}{n}

letsvbmbm

renewcommandbm{begingroupcatcode`<=active xbm}

newcommandxbm[1]{svbm{#1}endgroup}

letsvlt<

{catcode`<=active gdef<{mathop{mathrm{svlt}}}}

begin{document}

$a<bquadbm{a<b}quad ybm{-y}$

end{document}

To apply this approach to both < and > relations requires just a little extra:

documentclass{amsart}

usepackage[utf8]{inputenc}

usepackage[T1]{fontenc}

usepackage{eulerpx,bm}

SetSymbolFont{letters}{bold}    {U}{zeur}{m}{n}

letsvbmbm

renewcommandbm{begingroup%

  catcode`>=active %

  catcode`<=active %

  xbm}

newcommandxbm[1]{svbm{#1}endgroup}

letsvlt<

letsvgt>

{catcode`>=active 

gdef>{mathop{mathrm{svgt}}}

catcode`<=active 

gdef<{mathop{mathrm{svlt}}}}

begin{document}

$a<bquadbm{a<>b}quad ybm{-y}$

end{document}