diff --git a/lectures/match_transport.md b/lectures/match_transport.md index 03d926c6..c9ac52fe 100644 --- a/lectures/match_transport.md +++ b/lectures/match_transport.md @@ -53,7 +53,9 @@ We will refer to these two measures as *marginals*. We assume that -$$\sum_{x \in X} n_x = \sum_{y \in Y} m_y =: N$$ +$$ +\sum_{x \in X} n_x = \sum_{y \in Y} m_y =: N +$$ so that the matching problem is *balanced*. @@ -700,7 +702,7 @@ example_off_diag.plot_layers() Recall that layer $L_\ell$ consists of a list of distinct types from $Y \sqcup X$ $$ - z_1 < z_2\dots < z_{N_\ell-1} < z_{N_\ell}, +z_1 < z_2\dots < z_{N_\ell-1} < z_{N_\ell}, $$ which is alternating. @@ -1387,7 +1389,9 @@ The following example shows that composite matching can feature both positive an Suppose that there are two agents per side and types -$$ \textcolor{blue}{x_0} < \textcolor{red}{y_0} < \textcolor{blue}{x_1} < \textcolor{red}{y_1}$$ +$$ +\textcolor{blue}{x_0} < \textcolor{red}{y_0} < \textcolor{blue}{x_1} < \textcolor{red}{y_1} +$$ There are two feasible matchings, one corresponding to PAM, the other to NAM. @@ -1632,12 +1636,10 @@ The *dual problem* is $$ - \begin{aligned} V_D = \max_{\phi,\psi}& \sum_{x \in X }n_x \phi_x + \sum_{y \in Y} m_y \psi_y\\ \text{s.t. }& \phi_x + \psi_y \leq c_{xy} \\ \end{aligned} - $$ where $(\phi , \psi) $ are dual variables, which can be interpreted as shadow cost of agents in $X$ and $Y$, respectively. @@ -1909,6 +1911,7 @@ Indeed, for any subpair $(x_1,y_1)$ of $(x_0,y_0)$, the dual variables of all th But dual feasibility is not satisfied globally in general, for instance it might not be satisfied for two subpairs $(x_1,y_1)$ and $(x_2,y_2)$ of $(x_0,y_0).$ Therefore, letting $(x_1,y_1), \dots, (x_p,y_p)$ be the subpairs of $(x_0,y_0),$ we compute the solution $(\beta_2, \dots, \beta_p) $ of the linear system + $$ \max (c_{x_0 y_0} - c_{x_0 y_i} - c_{x_j y_0} , - c_{x_j y_i}) + c_{x_i y_i} \leq \sum_{k=i+1}^{j} \beta_k