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Elliptic curve basics + p-adics
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Tatiana Bradley committed Nov 5, 2014
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29 changes: 29 additions & 0 deletions latex/elliptic-curve-basics.tex
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\chapter{Elliptic Curve Basics}%
\label{sec:elliptic-curves}

% Weierstrass equation
\begin{defn}
Let $K$ be a field. An $\textbf{elliptic curve $E$ over $K$}$ is defined by an equation:
$$E : y^2 + a_1xy + a_3y = x^3 + a_2x^2 + a_4x + a_6$$
where $a_1, a_2, a_3, a_4, a_6 \in K$ and the $\textbf{discriminant}$ $\Delta$ is non-zero. This equation is called a $\textbf{Weierstrass equation}$.
\end{defn}

% L-rational points
\begin{defn}
With $K$ and $E$ defined as above, the set of $\textbf{L-rational points}$ on $E$ for any extension $L$ of $K$ is the set of pairs $(x, y) \in L \times L$ that
satisfy $E$, together with $\OO$, the point at infinity.

The set of L-rational points is denoted $E(L)$.
\end{defn}

% Trace of Frobenius
\begin{defn}
Let $E$ be an elliptic curve over a finite field $\finfield$. The $\textbf{trace of Frobenius}$ t is defined by:
$$ \#E(\finfield) = q + 1 - t, $$
where $\#E(\finfield)$ is the number of elements in $E(\finfield)$.
\end{defn}

\begin{rmk}
The trace of Frobenius is equal to one if and only if $E(\finfield)$ has exactly $q$ elements. This has important implications
for cryptography, as we will see.
\end{rmk}
12 changes: 12 additions & 0 deletions latex/formal-log.tex
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\chapter{Formal Power Series and Formal Logarithm}%
\label{sec:formal-log}

\section{Formal Power Series}

%% Defintion of
\begin{defn}
\end{defn}


\section{Formal Logarithm}
Hello
35 changes: 35 additions & 0 deletions latex/p-adics.tex
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\chapter{P-adic numbers}%
\label{sec:p-adics}

\section{The p-adics}

\begin{defn}
For a rational number $a$ and a prime number $p$, separate out all factors of $p$ from $a$ and write: $$ a = p^r \dfrac{m}{n} $$ where $r$, $m$ and $n$ are integers, and $p$ does not divide $m$ or $n$. The exponent $r$ is called the $\textbf{p-adic ordinal}$ of $a$, denoted $\text{ord}_p(a)$.
\end{defn}

% The absolute value
\begin{defn}
For a prime $p$, we define a function $|.|_p : \Q \to \Q_{\ge 0}$ where for $a \in \Q$:
$$
|a|_p = \left\{
\begin{array}{ll}
p^{-\text{ord}_p(a)} & \quad a \neq 0 \\
0 & \quad a = 0.
\end{array}
\right.
$$
The function $|.|_p$ is called the $\textbf{p-adic absolute value}$.
\end{defn}

\begin{prop}
The p-adic absolute value is a norm on $\Q$, and induces a metric $$d_p(a, \ b) = | a - b |_p$$ for $a, b \in \Q$.
\end{prop}

\begin{defn}
A p-adic number $a$ is called a $\textbf{p-adic integer}$ if $ord_p(a) \ge 0$. The set of all p-adic integers is
denoted $\Z_p$.
\end{defn}

\begin{rmk}
A p-adic integer is always of the form $$a_0 + a_1p + a_2p^2 + ... ,$$ i.e., all powers of $p$ are non-negative.
\end{rmk}
Binary file modified latex/thesis-wrapper.pdf
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27 changes: 26 additions & 1 deletion latex/thesis-wrapper.tex
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\advisor{Christopher Towse}
\reader{Second Reader}

%%% END HEADER %%%
%%% Including new commands and packages.
\usepackage{amsthm}
\newtheorem{thm}{Theorem}[chapter]
\newtheorem{lem}[thm]{Lemma}
\newtheorem{prop}[thm]{Proposition}
\newtheorem{cor}[thm]{Corollary}

\theoremstyle{definition}
\newtheorem{defn}[thm]{Definition}

\theoremstyle{remark}
\newtheorem*{rmk}{Remark}

\newcommand{\OO}{\mathcal{O}}
\newcommand{\Q}{\mathbb{Q}}
\newcommand{\Z}{\mathbb{Z}}
\newcommand{\NN}{\mathbb{N}}
\newcommand{\finfield}{\mathbb{F}_q}

%%% END HEADER %%%

\begin{document}

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\mainmatter

\include{intro}
\include{elliptic-curve-basics}
\include{formal-log}
\include{p-adics}
%\include{}
%\include{}
%\include{}
%\include{}

%%% End of the main matter.

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