``We do not require, but highly recommend that you try to solve all the homework exercises and if you do so, write them up. Writing up teaches you to precisely formulate your (maybe vague) ideas and communicate them such that others (in this case us) understand them. This ability is beneficial not just in mathematics but in (almost) any discipline. Whatever you write up we will read and comment on. Another reason to struggle with the homework problems is to prepare yourself for the final exam.'' --- http://www.ti.inf.ethz.ch/ew/courses/GT04/
Solutions to Exercises:
LI, Mu, Stable Marriage
LI, Yi, Lineae Codes and Weights
张镇华, 完美图, 数学传播，17卷4期
Daniel Marx, Trees, Tree Width, Hypertree Width, Fractional Hypertree Width.