MINIMUM K-STACKER CRANE PROBLEM

• INSTANCE: Mixed graph $G=\left(V,A,E\right)$, initial vertex $s\in V$, length $l(e)\in N$ for each $e\in A\cup E$,

• SOLUTION: A collection of k cycles, each containing the initial vertex s, that collectively traverse each directed edge in A at least once.

• MEASURE: The maximum length of the k cycles.

  
  

• Good News: Approximable within 14/5-1/k [171].