From f292c5a0e54c010bb7a00586a6e3c1b14831a5bc Mon Sep 17 00:00:00 2001 From: Yigit Sever Date: Sat, 7 Nov 2020 03:38:07 +0300 Subject: Polish question 2 --- main.tex | 34 +++++++++++++++++++++++----------- 1 file changed, 23 insertions(+), 11 deletions(-) diff --git a/main.tex b/main.tex index 3778cd4..21235f0 100644 --- a/main.tex +++ b/main.tex @@ -304,7 +304,7 @@ We have implemented \emph{Gale-Shapley} and an instance set creation script to t \section{Stable Matching Variation}% \label{sec:stable_matching_variation} -% stable matching question ALMOST {{{1 % +% stable matching question ✅ {{{1 % \begin{question} Consider a Stable Matching problem with men and women. @@ -313,12 +313,15 @@ We have implemented \emph{Gale-Shapley} and an instance set creation script to t Either give a proof that shows such an improvement is impossible, or give an example preference list for which an improvement for $w$ is possible. \end{question} -Example preference list for men; $M = {x,y,z}$ and women: $W = {a,b,c}$. +We will give an example instance. +Let's take the example preference list for men; $M = {x,y,z}$ and women: $W = {a,b,c}$. \begin{table}[!htb] - \caption{Preference lists of women.} + \caption{Preference lists of women}% + \label{table:2_general} \begin{minipage}{.5\linewidth} - \caption{Everyone is being truthful} + \caption{Everyone is being truthful}% + \label{table:2_true} \centering \begin{tabular}{l|lll} \textbf{a} & y & x & z \\ @@ -328,19 +331,22 @@ Example preference list for men; $M = {x,y,z}$ and women: $W = {a,b,c}$. \end{minipage}% \begin{minipage}{.5\linewidth} \centering - \caption{a is lying about their preference} + \caption{a is lying about their preference}% + \label{table:2_lie} \begin{tabular}{l|lll} \textbf{a} & y & z & x \\ \textbf{b} & x & y & z \\ \textbf{c} & x & y & z \end{tabular} \begin{tikzpicture}[overlay] - \draw[red, line width=1pt] (-0.72,0.52) ellipse (0.70cm and 0.2cm); + \draw[red, line width=1pt] (-0.72,0.52) ellipse (0.70cm and 0.2cm); \end{tikzpicture} \end{minipage} \end{table} -% TODO: final polish, highlight the lies <06-11-20, yigit> % +In the example given above in Table~\ref{table:2_general}, we have two cases for women, Table~\ref{table:2_true} where everyone has given their actual preference list and Table~\ref{table:2_lie} where $a$ has lied about their \nth{2} and \nth{3} preferences. + +The following is the men's preference table; \begin{table}[htb] \centering @@ -353,7 +359,7 @@ Example preference list for men; $M = {x,y,z}$ and women: $W = {a,b,c}$. \label{tab:men_pref} \end{table} -The trace of \emph{Gale-Shapley} algorithm for the truth telling case; +The trace of \emph{Gale-Shapley} algorithm for the truth telling case with Table~\ref{table:2_true} and Table~\ref{tab:men_pref} is below; \begin{enumerate} \item Matching x with a (a) @@ -363,30 +369,36 @@ The trace of \emph{Gale-Shapley} algorithm for the truth telling case; \item Matching z with c (a) \end{enumerate} +Which produces the following matching. Note that $a$ is matched with their \nth{2} choice. + \begin{align*} x &\rightarrow a \\ y &\rightarrow b \\ z &\rightarrow c \end{align*} -The trace of \emph{Gale-Shapley} algorithm when \emph{a} lies about their preferences; +Now let's examine the trace of the algorithm when $a$ lies by providing an altered preference table. The trace below uses Table~\ref{table:2_lie} and Table~\ref{tab:men_pref}; \begin{enumerate} \item Matching y with b (a) \item Matching z with a (a) - \item x proposes to a but gets rejected because a prefers z more (c) + \item \textbf{x proposes to a but gets rejected because a lies by saying that they like z more (c)} \item Matching x with b, y is now free (b) - \item Matching y with a, z is now free (b) + \item \textbf{Matching y with a, z is now free (b)} \item z proposes to b but gets rejected because b prefers x more (c) \item Matching z with c (a) \end{enumerate} +The highlighted lines show that $a$ lies when proposed by $x$ and then is able to trade up to $y$. The following it the final matching; + \begin{align*} x &\rightarrow b \\ y &\rightarrow a \\ z &\rightarrow c \end{align*} +Woman $a$ was able to get their highest preferred option $y$ by telling a lie. We have proved that an improvement is possible. + % 1}}} % \section{Asymptotics}% -- cgit v1.2.3-70-g09d2