The level of repair analysis (lora) gives answers to three questions that are posed when deciding on how to maintain capital goods: 1) which components to repair upon failure and which to discard, 2) at which locations in the repair network to perform each type of repairs, and 3) at which locations in the network to deploy resources, such as test equipment. The goal is to achieve the lowest pos...

We present a new model for a strategic locomotive scheduling problem arising at the Deutsche Bahn AG. The model is based on a multi-commodity min-cost flow formulation that is also used for public bus scheduling problems. However, several new aspects have to be additionally taken into account, such as cyclic departures of the trains, time windows on starting and arrival times, network-load depe...

We consider two related problems, the Minimum Bounded Degree Matroid Basis problem and the Minimum Bounded Degree Submodular Flow problem. The first problem is a generalization of the Minimum Bounded Degree Spanning Tree problem: we are given a matroid and a hypergraph on its ground set with lower and upper bounds f(e) ≤ g(e) for each hyperedge e. The task is to find a minimum cost basis which ...

We study the coarse-grained parallelization of an efficient bundle-based costdecomposition algorithm for the solution of multicommodity min-cost flow (MMCF) problems. We show that a code exploiting only the natural parallelism inherent in the costdecomposition approach, i.e., solving the min-cost flow subproblems in parallel, obtains satisfactory efficiencies even with many processors on large,...

Ridesharing platforms match drivers and riders to trips, using dynamic prices to balance supply and demand. A challenge is to set prices that are appropriately smooth in space and time, in the sense that drivers will choose to accept their dispatched trips, rather than drive to another area or wait for higher prices or a better trip. We introduce the Spatio-Temporal Pricing (STP) mechanism. The...

We motivate and introduce an extension of the well-known cumulative constraint which deals with time and volume dependent cost of resources. Our research is primarily interested in scheduling problems under time and volume variable electricity costs, but the constraint equally applies to manpower scheduling when hourly rates differ over time and/or extra personnel incur higher hourly rates. We ...

Efficient hosting of applications in a globally distributed multi-tenant cloud computing platform requires policies to decide where to place application replicas and how to distribute client requests among these replicas in response to the dynamic demand. We present a unified method that computes both policies together based on a sequence of min-cost flow models. Further, since optimization pro...

With the transfer of the Census of Agriculture to the National Agricultural Statistics Service within the Department of Agriculture it was recognized that the addition of the census and its follow-on surveys to the agency’s existing programs brought different issues and concerns regarding the confidentiality of data. The agency conducted a review of the multiple policies for disclosure control ...

Pierre Schaus, Pascal Van Hentenryck, Alessandro Zanarini Dynadec, Brown University {pschaus,pvh,alessandro.zanarini}@dynadec.com Abstract. The Soft Global Cardinality Constraint (softggc) relaxes the Global Cardinality Constraint (gcc) by introducing a violation variable representing unmet requirements on the number of value occurrences. A first domain consistent filtering algorithm was introd...

In this paper we consider the following pebble coordination problem. Consider a tree with n vertices and k pebbles located at distinct vertices of the tree. Each pebble can be moved from its current position to an adjacent unoccupied vertex. Among the k pebbles, one distinguished pebbles has been assigned a destination. We give an O(n5) algorithm for the problem of designing the shortest sequen...