Two mathematicians have proved that a straightforward question—how hard is it to untie a knot?—has a complicated answer.

Ulcerative colitis is a chronic, immune-mediated disorder of the colon, which is characterised by a relapsing–remitting course. Owing to the growing understanding of the immunopathogenesis of this ...

The line continues to shift for Texas A&M vs. South Carolina. After opening as a 16.5-point favorite, the Aggies are now ...