We define the stable 4–genus of a knot K ⊂ S3, gst(K), to be the limiting value of g4(nK)∕n, where g4 denotes the 4–genus and n goes to infinity. This induces a seminorm on the rationalized knot concordance group, CQ = C⊗ Q. Basic properties of gst are developed, as are examples focused on understanding the unit ball for gst on specified subspaces of CQ. Subspaces spanned by torus knots are used to illustrate the distinction between the smooth and topological categories. A final example is given in which Casson–Gordon invariants are used to demonstrate that gst(K) can be a noninteger.
Livingston, Charles  1
@article{10_2140_agt_2010_10_2191,
author = {Livingston, Charles},
title = {The stable 4{\textendash}genus of knots},
journal = {Algebraic and Geometric Topology},
pages = {2191--2202},
year = {2010},
volume = {10},
number = {4},
doi = {10.2140/agt.2010.10.2191},
url = {http://geodesic.mathdoc.fr/articles/10.2140/agt.2010.10.2191/}
}
Livingston, Charles. The stable 4–genus of knots. Algebraic and Geometric Topology, Tome 10 (2010) no. 4, pp. 2191-2202. doi: 10.2140/agt.2010.10.2191
[1] , Longueur stable des commutateurs, Enseign. Math. $(2)$ 37 (1991) 109
[2] , scl, MSJ Memoirs 20, Mathematical Society of Japan (2009)
[3] , Stable commutator length is rational in free groups, J. Amer. Math. Soc. 22 (2009) 941
[4] , , Cobordism of classical knots, from: "À la recherche de la topologie perdue" (editors L Guillou, A Marin), Progr. Math. 62, Birkhäuser (1986) 181
[5] , , Singularities of $2$–spheres in $4$-space and cobordism of knots, Osaka J. Math. 3 (1966) 257
[6] , On the slice genus of knots, Invent. Math. 66 (1982) 191
[7] , Slice knots in $S^{3}$, Quart. J. Math. Oxford Ser. $(2)$ 34 (1983) 305
[8] , , The Casson–Gordon invariant and link concordance, Topology 31 (1992) 475
[9] , Invariants of knot cobordism, Invent. Math. 8 $(1969)$, 98–110; addendum, ibid. 8 (1969) 355
[10] , The $4$–genus of connected sums of $(2,k)$–torus knots, personal communication (2009)
[11] , On a certain numerical invariant of link types, Trans. Amer. Math. Soc. 117 (1965) 387
[12] , , Knot Floer homology and the four-ball genus, Geom. Topol. 7 (2003) 615
[13] , Khovanov homology and the slice genus, Invent. Math. 182 (2010) 419
[14] , Some cobordism invariants for links, Proc. Cambridge Philos. Soc. 66 (1969) 251
[15] , Irrational stable commutator length in finitely presented groups, J. Mod. Dyn. 2 (2008) 499
Cité par Sources :