Baseball Elimination Problem

Recently we had a masterclass from Pitu Mirchandani on the subject of network flows. These network flow problems have been developed since the 1950’s an example of which is my previous post on Dijkstra’s algorithm. The main thing I took away from the masterclass was that the idea of shortest paths, maximum flows and min cost max flows can be used to describe and solve a surprisingly wide variety of problems.

One interesting problem which can be solved using the ideas of network flows is that of the baseball-elimination problem. Baseball in the USA consists of two different leagues which are each split up into three divisions of about 5 teams. During regular season each team plays 162 games in total, most of which are against teams in their division (76 vs same division, 66 vs same league, 20 vs different league). The aim of this is try and qualify for the playoffs, which can be done by finishing first in the division.

All this adds up to a desire to be able to work out whether it is possible to see if a particular team can still potentially win the division and make it to the playoffs given the current league standings. Solving this problem means that we have to look at tables that might look something like the one below.


Who can make the playoffs?

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