An algebraic classification of some links of codimension two
An algebraic classification of some links of codimension two
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DOI:
10.1090/s0002-9939-1977-0458439-1
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发表时间:
1977
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影响因子:
--
通讯作者:
C. Liang
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文献类型:
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作者:
C. Liang
For q > 2, J. Levine proved that two simple (2q 1)-knots are isotopic if and only if their Seifert matrices are equivalent. In this paper, we will prove the analogue of Levine's result for simple boundary (2q 1)links; we will show that: "For q > 3, two simple boundary (2q 1)-links are isotopic if and only if their Seifert matrices are I-equivalent (defined by some algebraic moves)." An n-link of multiplicity m, denoted by L = K1 U ... U Km is an embedding of m disjoint copies of the n-sphere (or homotopy spheres) Ki into the (n + 2)-sphere Sn+2. L is called boundary if it extends to an embedding of m disjoint orientable compact (n + 1)-manifolds Mi, called the Seifert manifolds, with aMi = Ki. Let X denote the link complement. Gutierrez [1] showed that an n-link of multiplicity m is boundary if and only if there is an epimorphism from 71(X) onto Fm, the free group in m generators, sending meridians to generators. An (2q 1)-link L is called simple if 7Ti(X) = 7Ti(VmS1) for i 2, Levine [5] proved that two simple (2q 1)-knots are isotopic if and only if their Seifert matrices are "equivalent" (defined by certain algebraic "moves" in [5], also called S-equivalent in [7]). In this paper, we will prove the analogue of Levine's Theorems 1-3 for simple boundary (2q 1)links, q > 3: two simple boundary (2q 1)-links are isotopic if and only if their "Seifert matrices" are related by certain algebraic "moves". Since our proofs are almost the same as those of [4] and [5], we will only give the outlines here. 1. For simplicity, we will consider only the (2q 1)-link of multiplicity 2. Everything considered here is in the smooth category. Let L = K1 u K2 be a boundary (2q 1)-link. According to [1], there exist two disjoint 2q-dimensional Seifert manifolds Ml and M2 for L, that is, WI= K1 and 3M2 = K2. Let A 1 be the corresponding Seifert matrix for the Received by the editors January 13, 1977 and, in revised form, February 28, 1977. AMS (MOS) subject classifications (1970). Primary 57C45, 57D40, 57D65.