Take five

This is a collection of five short notes on lambda-calculus:

An Easy Expansion Exercise, written at NTT, Basic Research Laboratories, Atsugi, Japan.
FD à la Church and FD à la Tait , written at Puri Ulun Carik, Ubud, Bali, Indonesia.
Zooming-in on Omega and lambda xxx.x & xxx, written at TUM, München, Germany.

They were written as divertimenti for myself. In the notes some novel ways of applying known techniques to obtain known results are presented (except for the last note which actually contains a new result).