An urgent call has gone out to the scientific modelling community to help fight against the COVID-19 pandemic. Two Cambridge mathematicians are helping to lead the charge.
How do mathematical models of COVID-19 work and should we believe them? We talk to an epidemiologist, who has been working flat out to inform the government, to find out more.
It's one of mathematics' most famous results: every "map" can be coloured using at most four colours. What it doesn't usually apply to, however, are real maps.