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A slice knot is a type of mathematical knot. In knot theory, a "knot" means an embedded circle in the 3-sphere : and that the 3-sphere can be thought of as the boundary of the four-dimensional ball : A knot is slice if it bounds a nicely embedded disk ''D'' in the 4-ball.〔.〕 What is meant by "nicely embedded" depends on the context, and there are different terms for different kinds of slice knots. If ''D'' is smoothly embedded in ''B4'', then ''K'' is said to be smoothly slice. If ''K'' is only locally flat (which is weaker), then ''K'' is said to be topologically slice. Every ribbon knot is smoothly slice. An old question of Fox asks whether every slice knot is actually a ribbon knot.〔.〕 The signature of a slice knot is zero.〔 The Alexander polynomial of a slice knot factors as a product where is some integral Laurent polynomial.〔, (p. 90 ).〕 This is known as the Fox–Milnor condition.〔.〕 The following is a list of all slice knots with 10 or fewer crossings; it was compiled using the (Knot Atlas ): 61, , , , , , , , , , , , , , , , , , , and . ==References== 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「slice knot」の詳細全文を読む スポンサード リンク
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