[Tex/LaTex] $\VDash$ Symbol in AMS math packages

amsfontsamsmath

I'm trying to typeset some homework that deals with set theory and in particular I'm trying to write the "model-theoretic" notion of forcing. I put model-theoretic in quotes because I don't know the proper name for it. There's the forcing relation given by $\Vdash$ (i.e. it looks like similar to ||-), and I'm looking for the relation that looks like ||=, i.e. kind of like the $\models$ symbol or $\vDash$ but with an extra vertical line.

The strange thing is that it looks like the AMS packages have $\nVDash$ (i.e. the negation of the symbol I'm looking for) available, but not $\VDash$. Detexify doesn't seem to be helping me here. Are there any symbols which look like the hypothetical $\VDash$ I'm looking for (hopefully within amsmath, amsfonts, or amssymb, as I usually like to cut down on the number of packages I need to install to maintain portability across machines)?

Best Answer

\models is defined as (use \pshow\models where \def\pshow#1{{\let\protect\show #1}}):

\mathrel{|}\joinrel\Relbar

In a similar fashion one could define \mmodels:

\DeclareRobustCommand{\mmodels}{\mathrel{||}\joinrel\Relbar}

Here's a visual of the two:

enter image description here

\documentclass{article}
\DeclareRobustCommand{\mmodels}{\mathrel{||}\joinrel \Relbar}
\begin{document}
$\models\ \mmodels$
\end{document}

Perhaps inserting \mkern-2mu between the two vertical rules would look a little better:

enter image description here

Related Question