140 likes | 190 Views
Explore the shifting algorithm technique for tree partitioning, including max-min, min-max, and size-constrained solutions. Optimal partitions ensure algorithm termination within a finite number of steps, guaranteeing an optimal result. Lemmas provide insights into down-shifting and component weights. Experience the power of the shifting algorithm in tree partitioning problems.
E N D
The shifting algorithm technique for the partitioning of trees
Tree partition 1 1 6 4 3 1 1 7 6 4 3 7
Problem • Max-min • Min-max • Size constrained min-max • Height-constrained min-max • Most uniform problem
4-partition 1 1 6 4 3 1 1 7 6 4 3 7
1 1 6 4 3 1 1 7 6 4 3 7
1 1 6 4 3 1 1 7 6 4 3 7
1 1 6 4 3 1 1 7 6 4 3 7
1 1 6 4 3 1 1 7 6 4 3 7
1 1 6 4 3 1 1 7 6 4 3 7
Definition • A above Q
Optimality • If A above Q, the algorithm continues. • If A is not optimal, the algorithm does not terminate at A. • Since the algorithm must terminate in a finite number of steps, the result is an optimal partition
Lemma1 Let A > Q. Then the algorithm does not terminate. It makes a down-shift with resulting down-component of weight ≥ Wmin(Q).
Lemma2 • Let A > Q. Let the application of one down-shift of the algorithm change A to A’. Then there exists an optimal partition Q’ such that A’≥ Q’.