\(

\def\cuberoot#1{\sqrt[3]{#1}} \def\fourthroot#1{\sqrt[4]{#1}}

\def\abspartial#1#2#3#4{\left|\,{\partial(#1,#2)\over\partial(#3,#4)}\,\right|} \def\absdeltal#1#2#3#4{\left|\,{\d(#1,#2)\over\d(#3,#4)}\,\right|} \def\dispop#1#2{\disfrac{\partial #1}{\partial #2}}

\def\definedas{\equiv}

\def\bb{{\bf b}} \def\bB{{\bf B}} \def\bsigma{\boldsymbol{\sigma}} \def\bx{{\bf x}} \def\bu{{\bf u}}

\def\Re{{\rm Re\hskip1pt}} \def\Reals{{\mathbb R\hskip1pt}} \def\Integers{{\mathbb Z\hskip1pt}} \def\Naturals{{\mathbb N\hskip1pt}} \def\Im{{\rm Im\hskip1pt}} \def\P{\mbox{P}}

\def\half{{\textstyle{1\over 2}}} \def\third{{\textstyle{1\over3}}} \def\fourth{{\textstyle{1\over 4}}} \def\fifth{{\scriptstyle{1\over 5}}} \def\sixth{{\textstyle{1\over 6}}}

\def\oA{\rlap{$A$}\kern2pt\overline{\phantom{\dis{}I}}\kern.5pt} \def\obA{\rlap{$A$}\kern2pt\overline{\phantom{\dis{}I}}\kern.5pt} \def\obX{\rlap{$X$}\kern2pt\overline{\phantom{\dis{}I}}\kern.5pt} \def\obY{\rlap{$Y$}\kern2pt\overline{\phantom{\dis{}I}}\kern.5pt} \def\obZ{\rlap{$Z$}\kern2pt\overline{\phantom{\dis{}I}}\kern.5pt}

\def\obc{\rlap{$c$}\kern2pt\overline{\phantom{\dis{}I}}\kern.5pt} \def\obd{\rlap{$d$}\kern2pt\overline{\phantom{\dis{}I}}\kern.5pt} \def\obk{\rlap{$k$}\kern2pt\overline{\phantom{\dis{}I}}\kern.5pt} \def\oba{\rlap{$a$}\kern2pt\overline{\phantom{\dis{}I}}\kern.5pt} \def\obb{\rlap{$b$}\kern1pt\overline{\phantom{\dis{}t}}\kern.5pt}

\def\obw{\rlap{$w$}\kern1pt\overline{\phantom{\dis{}t}}\kern.5pt}

\def\obz{\overline{z}}\kern.5pt}

\newcommand{\bx}{\boldsymbol{x}} \newcommand{\by}{\boldsymbol{y}}

\newcommand{\br}{\boldsymbol{r}} \renewcommand{\bk}{\boldsymbol{k}}

\def\cuberoot#1{\sqrt[3]{#1}} \def\fourthroot#1{\sqrt[4]{#1}} \def\fifthroot#1{\sqrt[5]{#1}} \def\eighthroot#1{\sqrt[8]{#1}} \def\twelfthroot#1{\sqrt[12]{#1}}

\def\dis{\displaystyle} %\def\definedas{\equiv}

\def\bq{{\bf q}} \def\bp{{\bf p}}

\def\abs#1{\left|\,#1\,\right|} \def\disfrac#1#2{{\displaystyle #1\over\displaystyle #2}}

\def\select#1{ \langle\, #1 \,\rangle } \def\autoselect#1{ \left\langle\, #1 \,\right\rangle }

\def\bigselect#1{ \big\langle\, #1 \,\big\rangle }

\renewcommand{\ba}{\boldsymbol{a}} \renewcommand{\bb}{\boldsymbol{b}} \newcommand{\bc}{\boldsymbol{c}} \newcommand{\bh}{\boldsymbol{h}} \newcommand{\bA}{\boldsymbol{A}} \newcommand{\bB}{\boldsymbol{B}} \newcommand{\bC}{\boldsymbol{C}} \newcommand{\definedas}{\equiv} \newcommand{\half}{\frac{1}{2}}

%\newcommand{\slfrac}[2]{\raisebox{0.5pt}{$\scriptstyle{}^{#1}\!/\!_{#2}$}} \def\slfrac#1#2{\raise.8ex\hbox{$\scriptstyle#1$}\!/\!\lower.5ex\hbox{$\scriptstyle#2$}}

\newcommand{\bsigma}{\boldsymbol \sigma} \newcommand{\abs}[1]{\left|\,#1\,\right|} \newcommand{\Rectangle}{\sqsubset\!\sqsupset}

\newcommand{\rectangle}{{% \ooalign{$\sqsubset\mkern3mu$\cr$\mkern3mu\sqsupset$\cr}%

% How to do fractions: for 1/2 use this in place: $\raise{0.8pt}{\scriptstyle{}^{1}\!/\!_{2}}$ % for n/m use this in place: $\raise{0.8pt}{\scriptstyle{}^{n}\!/\!_{m}}$

}}

\)