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We study the behavior of the Ozsváth–Szabó and Rasmussen knot concordance
invariants τ and s on Km,n, the (m,n)–cable of a knot K where m and n are
relatively prime. We show that for every knot K and for any fixed positive integer m,
both of the invariants evaluated on Km,n differ from their value on the torus
knot Tm,n by fixed constants for all but finitely many n > 0. Combining
this result together with Hedden’s extensive work on the behavior of τ on
(m,mr + 1)–cables yields bounds on the value of τ on any (m,n)–cable of K. In
addition, several of Hedden’s obstructions for cables bounding complex curves are
extended.
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