This week's seminar will be in the MALL (in the Physics Research Deck) and will be on Tuesday 28st October at 1.30pm. We will meet before the seminar at about 1.10pm in the common room just outside the MALL for tea, coffee, and (of course) biscuits.

I will go staight to the definition of an $R$-mac, skipping the history leading up to it. I will present a simple example and a simple non-example in some detail with the aim of bringing out the essential quality of an $R$-mac. I will then list, without proof, some interesting examples of $R$-macs, followed by some recent structural results. Time permitting, I will then talk about $T$-measurable structures and ultraproducts of $R$-macs.