Projective-dimension characterization of split links

Let BB be an mm-component closed braid, let H(B)H(B) denote its HOMFLYPT homology, and let RBR_B be the associated ring. A link is nn-split if it is equivalent to a split union of nn closed braids.

Split-link characterization. BB represents an nn-split link if and only if

pdRBH(B)mn.\operatorname{pd}_{R_B} H(B) \leq m-n.

The preceding theorem proves the forward implication and gives the same upper bound for an nn-split link, while the conjecture asserts the converse. If true, the projective dimension of HOMFLYPT homology would detect how many times a link can be split, rather than measuring its distance from being split via splitting number.

Sources & referencesView supporting material

Primary source

Hao Wu, “Betti Numbers of the HOMFLYPT Homology”, arXiv:1703.07257 (2018).

Progress summary

Never refreshed

Nothing recorded yet. Refresh searches the literature and the public web for attempts on this problem, and writes the first summary here.

Solutions 0

No solutions have been posted yet.