\usepackage[top=1.5cm,bottom=1.5cm,left=1.5cm,right=1.5cm]{geometry}
\usepackage[utf8]{inputenc}
\usepackage{amsmath}
\usepackage{amssymb}
\usepackage{amsfonts}
\usepackage{amsthm}
\usepackage{enumerate}
\usepackage{hyperref}
\usepackage{mathtools}
\usepackage{multicol}
\usepackage{nicefrac}
\usepackage{relsize}
\usepackage{stmaryrd}

\makeatletter
\newtheoremstyle{plaintext}
{20pt}
{20pt}
{\normalfont}
{}
{\bfseries}
{.}
{\newline}
{\thmname{#1}\thmnumber{ #2}\thmnote{ (#3)}}
\makeatother
\theoremstyle{plaintext}

\newtheorem{formula}{Formula}
\providecommand*{\formulaautorefname}{Formula}

\newcommand{\NN}{\mathbb{N}}
\newcommand{\ZZ}{\mathbb{Z}}
\newcommand{\QQ}{\mathbb{Q}}
\newcommand{\RR}{\mathbb{R}}
\newcommand{\CC}{\mathbb{C}}

\newcommand{\inv}{^{-1}}
\newcommand{\abs}[1]{\left\lvert #1 \right\rvert}
\newcommand{\dx}{\, \mathrm{d}x}

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\DeclareMathOperator{\mdeg}{mdeg}
\DeclareMathOperator*{\bigplus}{\mathlarger{\mathlarger{\mathlarger{+}}}}

\allowdisplaybreaks