Merge pull request #5 from anherm/master

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Begin chapter on generating functions

Signed-off-by: Nicolai Hähnle <haehnle@or.uni-bonn.de>
Triangulations and basic definitions of algebra of polyhedra

Signed-off-by: Nicolai Hähnle <haehnle@or.uni-bonn.de>
Generating functions and Euler characteristic

Signed-off-by: Nicolai Hähnle <haehnle@or.uni-bonn.de>
Merge pull request #3 from nhaehnle/master

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