Tie a trefoil knot in a piece of string, seal the ends together, and try to wiggle it free without cutting. In three-dimensional space, the knot holds firm. Add a fourth spatial dimension, however, ...

The hypnotic Celtic knot might not be as complicated as it seems. Fourth-year math major Benjamin Liu, from Northampton, Mass., has broken the Celtic knot into 12 standard segments that can be ...

The bowline, clove hitch, and square are knots familiar to campers who might need to, say, tie down a tent with rope. But there are naturally occurring knots, too—ones that can be found on the ...