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  1. Math

    The Tangled Task of Distinguishing Knots

    Consider the plight of a gardener struggling with a recalcitrant tangle of garden hose. Sometimes, no amount of pulling or twisting unsnarls the coils. At other times, the tangles readily come apart, and the hose emerges unknotted. Trefoil knot. Different views of the figure-eight knot. Robert Scharein Braid (left) and its closed form (right). Robert […]

    By Ivars Peterson
  2. Math

    Pinpointing Prey

    Eight command neurons (black) represent the eight directions of the legs from which they receive input. Partner neurons (gray) send inhibitory signals. van Hemmen et al./Physical Review Letters Under cover of darkness, a burrowing cockroach skitters across the desert sand. Its rapidly moving legs excite tiny ripples that travel along the ground, tipping off a […]

    By Ivars Peterson
  3. Math

    A Graceful Sculpture’s Showy Snow Crash

    Brent Collins has spent more than two decades carving gracefully curvaceous sculptures out of wood.