In 1979 decorating work in a house in Vienna revealed a set of medieval frescoes depicting a cycle of songs by a 13th century poet, who was particularly fond of satirising the erotic relationships between knights and peasant maidens. The frescoes are of great historical significance, but they are badly damaged. In this article Carola Schönlieb explores how mathematicians use the heat equation to fill in the gaps.

These are busy times for Plus. Apart from celebrating our 50th issue by putting together a bumper collection of in-depth articles, news and reviews, we're also working on various special projects, some of which have already gone live, and some of which will reach you over the next few weeks and months. Here's a sneak preview of what's in store for 2009...

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