2022/07/16 by Harlander, Jens, Rosebrock, Stephan · 1 citation
#20F06 #20F65 #57K12 #57K20 #57K45 #57M15 #FOS: Mathematics #Geometric Topology (math.GT)
paper · doi:10.48550/arxiv.2207.07991
Labeled oriented trees, LOT's, encode spines of ribbon discs in the 4-ball and ribbon 2-knots in the 4-sphere. The unresolved asphericity question for these spines is a major test case for Whitehead's asphericity conjecture. In this paper we give a complete description of the link of a reduced injective LOT complex. An important case is the following: If Γ is a reduced injective LOT that does not contain boundary reduced sub-LOTs, then lk(K(Γ)) is a bi-forest. As a consequence K(Γ) is aspherical, in fact DR, and its fundamental group is locally indicable. We also show that a general injective LOT complex is aspherical. Some of our results have already appeared in print over the last two decades and are collected here.