Rowmotion on the chain of V's poset and whirling dynamics

Given a finite poset $P$, we study the whirling action on vertex-labelings of $P$ with the elements $\{0,1,2,\dots ,k\}$. When such labelings are (weakly) order-reversing, we call them $k$-bounded $P$-partitions. We give a general equivariant bijection between $k$-bounded $P$-partitions and order ideals of the poset $P\times [k]$ which conveys whirling to the well-studied rowmotion operator. As an application, we derive periodicity and homomesy results for rowmotion acting on the chain of V’s poset $V\times [k]$. We are able to generalize some of these results to the more complicated dynamics of rowmotion on $C_n\times [k]$, where $C_n$ is the claw poset with $n$ unrelated elements each covering $\widehat{0}$.