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**Title:** Seifert Surface of the Trefoil

**Artist and Designer:** Matthew Wright

**Materials:** Acrylic yarn and wire

**Technique:** Crochet

**Artist’s Statement:** If you take a strip of paper, twist
it once and a half, and tape the ends together, the surface you get will
have the trefoil knot as its boundary. But is there an orientable surface—one
with two diﬀerent sides—that has the trefoil as its boundary? And in general,
what knots or links are the boundary of some orientable surface? It turns
out that they all are: we can always ﬁnd an orientable surface (in fact,
many) with a given knot or link as its boundary. Such surfaces are called
Seifert surfaces, and they are a useful tool in knot theory.