237,541 research outputs found
Sharing Non-Anonymous Costs of Multiple Resources Optimally
In cost sharing games, the existence and efficiency of pure Nash equilibria
fundamentally depends on the method that is used to share the resources' costs.
We consider a general class of resource allocation problems in which a set of
resources is used by a heterogeneous set of selfish users. The cost of a
resource is a (non-decreasing) function of the set of its users. Under the
assumption that the costs of the resources are shared by uniform cost sharing
protocols, i.e., protocols that use only local information of the resource's
cost structure and its users to determine the cost shares, we exactly quantify
the inefficiency of the resulting pure Nash equilibria. Specifically, we show
tight bounds on prices of stability and anarchy for games with only submodular
and only supermodular cost functions, respectively, and an asymptotically tight
bound for games with arbitrary set-functions. While all our upper bounds are
attained for the well-known Shapley cost sharing protocol, our lower bounds
hold for arbitrary uniform cost sharing protocols and are even valid for games
with anonymous costs, i.e., games in which the cost of each resource only
depends on the cardinality of the set of its users
Information Flow in Secret Sharing Protocols
The entangled graph states have emerged as an elegant and powerful quantum
resource, indeed almost all multiparty protocols can be written in terms of
graph states including measurement based quantum computation (MBQC), error
correction and secret sharing amongst others. In addition they are at the
forefront in terms of implementations. As such they represent an excellent
opportunity to move towards integrated protocols involving many of these
elements. In this paper we look at expressing and extending graph state secret
sharing and MBQC in a common framework and graphical language related to flow.
We do so with two main contributions.
First we express in entirely graphical terms which set of players can access
which information in graph state secret sharing protocols. These succinct
graphical descriptions of access allow us to take known results from graph
theory to make statements on the generalisation of the previous schemes to
present new secret sharing protocols.
Second, we give a set of necessary conditions as to when a graph with flow,
i.e. capable of performing a class of unitary operations, can be extended to
include vertices which can be ignored, pointless measurements, and hence
considered as unauthorised players in terms of secret sharing, or error qubits
in terms of fault tolerance. This offers a way to extend existing MBQC patterns
to secret sharing protocols. Our characterisation of pointless measurements is
believed also to be a useful tool for further integrated measurement based
schemes, for example in constructing fault tolerant MBQC schemes
Absolutely Maximally Entangled States: Existence and Applications
We investigate absolutely maximally entangled (AME) states, which are
multipartite quantum states that are maximally entangled with respect to any
possible bipartition. These strong entanglement properties make them a powerful
resource for a variety of quantum information protocols. In this paper, we show
the existence of AME states for any number of parties, given that the dimension
of the involved systems is chosen appropriately. We prove the equivalence of
AME states shared between an even number of parties and pure state threshold
quantum secret sharing (QSS) schemes, and prove necessary and sufficient
entanglement properties for a wider class of ramp QSS schemes. We further show
how AME states can be used as a valuable resource for open-destination
teleportation protocols and to what extend entanglement swapping generalizes to
AME states
Quantifying the resource of sharing a reference frame
We define a new quantity called refbit, which allows one to quantify the
resource of sharing a reference frame in quantum communication protocols. By
considering both asymptotic and nonasymptotic protocols we find relations
between refbits and other communication resources. We also consider the same
resources in encoded, reference-frame independent, form. This allows one to
rephrase and unify previous work on phase references, reference frames, and
superselection rules.Comment: Updated title as PRA did not accept the word "refbit" in the title:
PRA accepts neither neologisms (="a meaningless word coined by a psychotic",
according to Webster), nor novophasm
Resource-Aware Protocols for Network Cost-Sharing Games
We study the extent to which decentralized cost-sharing protocols can achieve good price of anarchy (PoA) bounds in network cost-sharing games with agents. We focus on the model of resource-aware protocols, where the designer has prior access to the network structure and can also increase the total cost of an edge(overcharging), and we study classes of games with concave or convex cost functions. We first consider concave cost functions and our main result is a cost-sharing protocol for symmetric games on directed acyclic graphs that achieves a PoA of for some arbitrary small positive , which improves to for games with at least two players. We also achieve a PoA of 1 for series-parallel graphs and show that no protocol can achieve a PoA better than for multicast games. We then also consider convex cost functions and prove analogous results for series-parallel networks and multicast games, as well as a lower bound of for the PoA on directed acyclic graphs without the use of overcharging
Federal Taxation: Formal Stockholder Vote Held Controlling in Determining When a Plan of Liquidation Is Adopted Under Section 337 of the Internal Revenue Code of 1954
The correctness of real-time systems does not only depend on the validity of the output, but also the temporal validity. Tasks are typically designed with strict deadlines and they need to respond in time, which are the timing constraints of real-time systems. Schedulability analysis is one of the approaches to study the workload of the task system. DRTRS (Digraph Real-Time task model with resource sharing) is introduced to describe the system task model, abstracting away most functional behaviour and focus on the timing properties. We have also developed an efficient schedulability analysis under different resource access protocols
Opaque analysis for resource-sharing components in hierarchical real-time systems : extended version
A real-time component may be developed under the assumption that it has the entire platform at its disposal. Composing a real-time system from independently developed components may require resource sharing between components. We propose opaque analysis methods to integrate resource-sharing components into hierarchically scheduled systems. Resource sharing imposes blocking times within an individual component and between components. An opaque local analysis ignores global blocking between components and allows to analyse an individual component while assuming that shared resources are exclusively available for a component. To arbitrate mutually exclusive resource access between components, we consider four existing protocols: SIRAP, BROE and HSRP - comprising overrun with payback (OWP) and overrun without payback (ONP). We classify local analyses for each synchronization protocol based on the notion of opacity and we develop new analysis for those protocols that are non-opaque. Finally, we compare SIRAP, ONP, OWP and BROE by means of an extensive simulation study. From the results, we derive guidelines for selecting a global synchronization protocol
Designing cost-sharing methods for Bayesian games
We study the design of cost-sharing protocols for two fundamental resource allocation problems, the Set Cover and the Steiner Tree Problem, under environments of incomplete information (Bayesian model). Our objective is to design protocols where the worst-case Bayesian Nash equilibria, have low cost, i.e. the Bayesian Price of Anarchy (PoA) is minimized. Although budget balance is a very natural requirement, it puts considerable restrictions on the design space, resulting in high PoA. We propose an alternative, relaxed requirement called budget balance in the equilibrium (BBiE).We show an interesting connection between algorithms for Oblivious Stochastic optimization problems and cost-sharing design with low PoA. We exploit this connection for both problems and we enforce approximate solutions of the stochastic problem, as Bayesian Nash equilibria, with the same guarantees on the PoA. More interestingly, we show how to obtain the same bounds on the PoA, by using anonymous posted prices which are desirable because they are easy to implement and, as we show, induce dominant strategies for the players
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