Double square intersection symbol ⩎

Question

I want this ⩎ symbol I tried using \Sqcap but latex gave me the error : "undefined control sequence" Am i missing something?

This is my code:

    \documentclass[conference]{IEEEtran}
\IEEEoverridecommandlockouts
% The preceding line is only needed to identify funding in the first footnote. If that is unneeded, please comment it out.
\usepackage{cite}
\usepackage{amsmath,amssymb,amsfonts,amsthm}
\usepackage{algorithmic}
\usepackage{graphicx}
\usepackage{unicode-math}
\usepackage{textcomp}   
\usepackage{xcolor}
\def\BibTeX{{\rm B\kern-.05em{\sc i\kern-.025em b}\kern-.08em
    T\kern-.1667em\lower.7ex\hbox{E}\kern-.125emX}}
\allowdisplaybreaks[3]
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{amsmath}
%\usepackage{setspace}
%\usepackage[all,cmtip]{xy}
%\usepackage{arydshln}
\usepackage{color}
\usepackage{pdfpages}
\usepackage{graphicx}
%\usepackage{xy}
%\usepackage{textcomp}
\usepackage{amscd}
%\usepackage{latexsym}
%\usepackage{stmaryrd}
\usepackage{enumitem}
\usepackage{listings}
\usepackage{amsthm}
\usepackage{tikz}
  \usetikzlibrary{automata, positioning, arrows}
\input xy 
\xyoption{all}
%\xyoption{all}
\input{dinmacros.tex}
\usepackage{mathtools}
\usepackage{float}
%\pagestyle{plain}
\usepackage{bookmark}
\usepackage{booktabs}
\usepackage{hyperref}
%\usepackage[pdfencoding=auto]{hyperref}
\usepackage{subfig}
\usepackage{tikz}
\usepackage{tikz-network}
\usetikzlibrary{automata,positioning,calc,shapes.multipart}
\tikzstyle{obj} =[circle, minimum width=0.5cm, minimum height=0.5cm, draw=black]
\overfullrule=0.2mm
\def\justl#1#2{\
        &#1& \rule{2em}{0pt} {
        \mbox{\rule[-.7em]{0pt}{1.8em} \footnotesize{#2}} } \ && }
\def\cat#1{{\sf #1}}
\def\setcat{\cat{Set}}
\def\Mmax{\cat{MAX}}
\def\Mmin{\cat{MIN}}
\def\bmax{\cat{max}}
\def\bmin{\cat{min}}
\newcommand{\fdec}[3]{#1: #2 \longrightarrow #3}
\newcommand{\rfdec}[3]{#1: #2 \rightarrow #3}
\def\setdef#1#2{{#1; |;#2}}             % { f(x) | p(x) }
\def\enset#1{\mathopen{ { }#1\mathclose{ } }} % {a,b,...z}
\newtheorem{definition}{Definition}
\newtheorem{theorem}{Theorem}
\newtheorem{corollary}{Corollary}
\newtheorem{lemma}{Lemma}
\newtheorem{example}{Example}
%\newtheorem{proof}{proof.}
\newenvironment{proof}{\noindent \textbf{Proof.}}
\begin{document}
\begin{definition} Given a \emph{iMTL-algebra \pmb{A}} enriched with a metric $d$, a \emph{\pmb{A}- twisted algebra} $\pmb{A^2}=\langle A \times A, \Sqcap \rangle$ is defined as:
\for any $(a,b),, (c,d) \in A \times A$
\end{definition}
\end{document}

Answer 1

The mathabx package defines \sqdoublecap (and \sqdoublecup for ⩏):

\documentclass{article}
\usepackage{mathabx}
\begin{document}
Double square intersection: $\sqdoublecap$
\end{document}

Answer 2

Since you're using unicode-math and IEEEtran, you should use Times as the text font and you can exploit the STIX Two fonts.

\documentclass[conference]{IEEEtran}
\IEEEoverridecommandlockouts
% The preceding line is only needed to identify funding in the first footnote. If that is unneeded, please comment it out.
\usepackage{cite}
\usepackage{amsmath,amsthm}
\usepackage{algorithmic}
\usepackage{graphicx}
\usepackage{unicode-math}
\usepackage{textcomp}   
\usepackage{xcolor}
\usepackage[all,cmtip]{xy}
\usepackage{pdfpages}
\usepackage{enumitem}
\usepackage{listings}
\usepackage{tikz}
\usetikzlibrary{automata, positioning, arrows}
\usetikzlibrary{automata,positioning,calc,shapes.multipart}
\usepackage{tikz-network}
\usepackage{mathtools}
\usepackage{float}
\usepackage{booktabs}
\usepackage[caption=false]{subfig}
\usepackage{hyperref}
\usepackage{bookmark}
\tikzstyle{obj} =[circle, minimum width=0.5cm, minimum height=0.5cm, draw=black]
%\input{dinmacros.tex}
\setmainfont{STIX Two Text}
\setmathfont{STIX Two Math}
\newcommand\justl[2]{\
        &#1& \rule{2em}{0pt} {
        \mbox{\rule[-.7em]{0pt}{1.8em} \footnotesize #2} } \ && }
\newcommand\cat[1]{\mathsf{#1}}
\newcommand\setcat{\cat{Set}}
\newcommand\Mmax{\cat{MAX}}
\newcommand\Mmin{\cat{MIN}}
\newcommand\bmax{\cat{max}}
\newcommand\bmin{\cat{min}}
\newcommand{\fdec}[3]{#1: #2 \longrightarrow #3}
\newcommand{\rfdec}[3]{#1: #2 \rightarrow #3}
\newcommand\setdef[2]{{#1; |;#2}}             % { f(x) | p(x) }
\newcommand\enset[1]{\mathopen{ { }#1\mathclose{ } }} % {a,b,...z}
\newtheorem{definition}{Definition}
\newtheorem{theorem}{Theorem}
\newtheorem{corollary}{Corollary}
\newtheorem{lemma}{Lemma}
\newtheorem{example}{Example}
%\newtheorem{proof}{proof.}
%\newenvironment{proof}{\noindent \textbf{Proof.}}
\begin{document}
\begin{definition} 
Given a \emph{iMTL-algebra} $\symbfit{A}$ enriched with a metric $d$, an 
\emph{$\symbfit{A}$-twisted algebra} 
$\symbfit{A}^2=\langle A \times A, \Sqcap \rangle$ is defined as:
for any $(a,b),, (c,d) \in A \times A$
\end{definition}
\end{document}

Please, check the modified preamble, where I got rid of duplication and suggested other necessary changes.