Signatures of Lefschetz fibrations

In his Ph. D. thesis, Burak Ozbagci described an algorithm computing signatures of Lefschetz fibrations where the input is a factorization of the monodromy into a product of Dehn twists. I will talk about a reformulation  of Ozbagci's algorithm which becomes much easier to implement. Our  main tool  will be Wall's non-additivity formula applied to what I call partial fiber sum decomposition of a Lefschetz fibrations over disk. This is a joint work with A. Cengel.