On the 2-chain subgraph cover and related problems
Journal of Algorithms
On the fractional dimension of partially ordered sets
Discrete Mathematics - Special issue: trends in discrete mathematics
Scheduling to minimize average completion time: off-line and on-line approximation algorithms
Mathematics of Operations Research
Scheduling to minimize average completion time: off-line and on-line algorithms
Proceedings of the seventh annual ACM-SIAM symposium on Discrete algorithms
Precedence constrained scheduling to minimize sum of weighted completion times on a single machine
Discrete Applied Mathematics
Two-Dimensional Gantt Charts and a Scheduling Algorithm of Lawler
SIAM Journal on Discrete Mathematics
Some APX-completeness results for cubic graphs
Theoretical Computer Science
On the power of unique 2-prover 1-round games
STOC '02 Proceedings of the thiry-fourth annual ACM symposium on Theory of computing
Proceedings of the 5th International IPCO Conference on Integer Programming and Combinatorial Optimization
Partially-Ordered Knapsack and Applications to Scheduling
ESA '02 Proceedings of the 10th Annual European Symposium on Algorithms
Single-Machine Scheduling with Precedence Constraints
Mathematics of Operations Research
FOCS '07 Proceedings of the 48th Annual IEEE Symposium on Foundations of Computer Science
Scheduling with Precedence Constraints of Low Fractional Dimension
IPCO '07 Proceedings of the 12th international conference on Integer Programming and Combinatorial Optimization
On the approximability of average completion time scheduling under precedence constraints
Discrete Applied Mathematics
Optimal Long Code Test with One Free Bit
FOCS '09 Proceedings of the 2009 50th Annual IEEE Symposium on Foundations of Computer Science
Conditional hardness of precedence constrained scheduling on identical machines
Proceedings of the forty-second ACM symposium on Theory of computing
Approximating precedence-constrained single machine scheduling by coloring
APPROX'06/RANDOM'06 Proceedings of the 9th international conference on Approximation Algorithms for Combinatorial Optimization Problems, and 10th international conference on Randomization and Computation
Operations Research Letters
Single machine scheduling with scenarios
Theoretical Computer Science
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We consider the single-machine scheduling problem to minimize the weighted sum of completion times under precedence constraints. In a series of recent papers, it was established that this scheduling problem is a special case of minimum weighted vertex cover. In this paper, we show that the vertex cover graph associated with the scheduling problem is exactly the graph of incomparable pairs defined in the dimension theory of partial orders. Exploiting this relationship allows us to present a framework for obtaining (2-2/f)-approximation algorithms, provided that the set of precedence constraints has fractional dimension of at most f. Our approach yields the best-known approximation ratios for all previously considered special classes of precedence constraints, and it provides the first results for bounded degree and orders of interval dimension 2. On the negative side, we show that the addressed problem remains NP-hard even when restricted to the special case of interval orders. Furthermore, we prove that the general problem, if a fixed cost present in all feasible schedules is ignored, becomes as hard to approximate as vertex cover. We conclude by giving the first inapproximability result for this problem, showing under a widely believed assumption that it does not admit a polynomial-time approximation scheme.