Alberto Marchetti-Spaccamela

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—Systems in many safety-critical application domains are subject to certification requirements. For any given system, however, it may be the case that only a subset of its functionality is safety-critical and hence subject to certification; the rest of the functionality is non safety critical and does not need to be certified, or is certified to a lower(More)
We consider the scheduling of mixed-criticality task systems, that is, systems where each task to be scheduled has multiple levels of worst-case execution time estimates. We design a scheduling algorithm, EDF-VD, whose effectiveness we analyze using the processor speedup metric: we show that any 2-level task system that is schedulable on a unit-speed(More)
Many safety-critical embedded systems are subject to certification requirements; some systems may be required to meet multiple sets of certification requirements, from different certification authorities. Certification requirements in such " mixed-criticality " systems give rise to interesting scheduling problems , that cannot be satisfactorily addressed(More)
We consider a version of multiprocessor scheduling with the special feature that jobs may be rejected at a certain penalty. An instance of the problem is given by m identical parallel machines and a set of n jobs, each job characterized by a processing time and a penalty. In the on-line version the jobs become available one by one and we have to schedule or(More)
This paper gives probabilistic analyses of two kinds of multidimensional bin packing problems: vector packing and rectangle packing. In the vector packing problem each of the <italic>d</italic> dimensions can be interpreted as a resource. A given object <italic>i</italic> consumes <italic>a</italic><subscrpt>ij</subscrpt> units of the(More)
A sensor network consists of sensing devices which may exchange data through wireless communication; sensor networks are highly energy constrained since they are usually battery operated. Data aggregation is a possible way to save energy consumption: nodes may delay data in order to aggregate them into a single packet before forwarding them towards some(More)
We present two <i>space bounded</i> random sampling algorithms that compute an approximation of the number of triangles in an undirected graph given as a stream of edges. Our first algorithm does not make any assumptions on the order of edges in the stream. It uses space that is inversely related to the ratio between the number of triangles and the number(More)
In this paper we study some aspects of weighted flow time. We first show that the online algorithm Highest Density First is an O(1)-speed O(1)-approximation algorithm for P |r i , pmtn| w i F i. We then consider a related Deadline Scheduling Problem that involves minimizing the weight of the jobs unfinished by some unknown deadline D on a uniprocessor. We(More)