Have definitions at top in "glossary" chapter.

finite-set-exercises
Joshua Potter 2023-05-13 07:14:03 -06:00
parent b413998f6b
commit e1af33e805
1 changed files with 47 additions and 46 deletions

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@ -17,6 +17,53 @@
\tableofcontents
\chapter{Glossary}%
\label{chap:glossary}
\section{\defined{Partition}}%
\label{sec:def-partition}
Let $[a, b]$ be a closed interval decomposed into $n$ subintervals by inserting
$n - 1$ points of subdivision, say $x_1$, $x_2$, $\ldots$, $x_{n-1}$, subject
only to the restriction
\begin{equation}
\label{sec:partition-eq1}
a < x_1 < x_2 < \cdots < x_{n-1} < b.
\end{equation}
It is convenient to denote the point $a$ itself by $x_0$ and the point $b$ by
$x_n$.
A collection of points satisfying \eqref{sec:partition-eq1} is called a
\textbf{partition} $P$ of $[a, b]$, and we use the symbol
$$P = \{x_0, x_1, \ldots, x_n\}$$ to designate this partition.
\begin{definition}
\lean{Common/Set/Intervals/Partition}{Set.Intervals.Partition}
\end{definition}
\section{\defined{Step Function}}%
\label{sec:def-step-function}
A function $s$, whose domain is a closed interval $[a, b]$, is called a step
function if there is a \nameref{sec:def-partition}
$P = \{x_0, x_1, \ldots, x_n\}$ of $[a b]$ such that $s$ is constant on each
open subinterval of $P$.
That is to say, for each $k = 1, 2, \ldots, n$, there is a real number $s_k$
such that $$s(x) = s_k \quad\text{if}\quad x_{k-1} < x < x_k.$$
Step functions are sometimes called piecewise constant functions.
\vspace{8pt}
\noindent
\textit{Note:} At each of the endpoints $x_{k-1}$ and $x_k$ the function must
have some well-defined value, but this need not be the same as $s_k$.
\begin{definition}
\lean{Common/Set/Intervals/StepFunction}{Set.Intervals.StepFunction}
\end{definition}
\chapter{A Set of Axioms for the Real-Number System}%
\label{chap:set-axioms-real-number-system}
@ -1085,52 +1132,6 @@ Prove that the set function $n$ satisfies the first three axioms for area.
\end{proof}
\chapter{Partitions and Step Functions}%
\label{chap:partitions-step-functions}
\section{\defined{Partition}}%
\label{sec:partition}
Let $[a, b]$ be a closed interval decomposed into $n$ subintervals by inserting
$n - 1$ points of subdivision, say $x_1$, $x_2$, $\ldots$, $x_{n-1}$, subject
only to the restriction
\begin{equation}
\label{sec:partition-eq1}
a < x_1 < x_2 < \cdots < x_{n-1} < b.
\end{equation}
It is convenient to denote the point $a$ itself by $x_0$ and the point $b$ by
$x_n$.
A collection of points satisfying \eqref{sec:partition-eq1} is called a
\textbf{partition} $P$ of $[a, b]$, and we use the symbol
$$P = \{x_0, x_1, \ldots, x_n\}$$ to designate this partition.
\begin{definition}
\lean{Common/Set/Intervals/Partition}{Set.Intervals.Partition}
\end{definition}
\section{\defined{Step Function}}%
\label{sec:step-function}
A function $s$, whose domain is a closed interval $[a, b]$, is called a step
function if there is a \nameref{sec:partition} $P = \{x_0, x_1, \ldots, x_n\}$
of $[a b]$ such that $s$ is constant on each open subinterval of $P$.
That is to say, for each $k = 1, 2, \ldots, n$, there is a real number $s_k$
such that $$s(x) = s_k \quad\text{if}\quad x_{k-1} < x < x_k.$$
Step functions are sometimes called piecewise constant functions.
\vspace{8pt}
\noindent
\textit{Note:} At each of the endpoints $x_{k-1}$ and $x_k$ the function must
have some well-defined value, but this need not be the same as $s_k$.
\begin{definition}
\lean{Common/Set/Intervals/StepFunction}{Set.Intervals.StepFunction}
\end{definition}
\chapter{Exercises 1.11}%
\label{chap:exercises-1-11}