# Tag: maths

• ## Measuring Angles within Arbitrary Metric Spaces

We will generalise the concept of angles in Euclidean space to any arbitrary metric space, via Alexandrov (upper) angles.

• ## Hilbert's Hotel, but the Guests are Mere Mortals

We will consider a variation of Hilbert’s hotel, within which guests may not be relocated too far from their current room.

• ## An Upper Bound on Ramsey Numbers (Revision Season)

I will present a short argument on an upper bound for $$r(s)$$, the Ramsey Number associated with the natural number $$s$$.

• ## Counting Derangements

I present an inefficient yet novel way of recursively counting derangements of a set, and generalise this to counting permutations without short cycles.