Towards formal models and languages for verifiable Multi-Robot Systems

Incorrect operations of a Multi-Robot System (MRS) may not only lead to unsatisfactory results, but can also cause economic losses and threats to safety. These threats may not always be apparent, since they may arise as unforeseen consequences of the interactions between elements of the system. This call for tools and techniques that can help in providing guarantees about MRSs behaviour. We think that, whenever possible, these guarantees should be backed up by formal proofs to complement traditional approaches based on testing and simulation. We believe that tailored linguistic support to specify MRSs is a major step towards this goal. In particular, reducing the gap between typical features of an MRS and the level of abstraction of the linguistic primitives would simplify both the specification of these systems and the verification of their properties. In this work, we review different agent-oriented languages and their features; we then consider a selection of case studies of interest and implement them useing the surveyed languages. We also evaluate and compare effectiveness of the proposed solution, considering, in particular, easiness of expressing non-trivial behaviour.Comment: Changed formattin

Importance Sampling Scheme for the Stochastic Simulation of Quantum Spin Dynamics

The numerical simulation of dynamical phenomena in interacting quantum systems is a notoriously hard problem. Although a number of promising numerical methods exist, they often have limited applicability due to the growth of entanglement or the presence of the so-called sign problem. In this work, we develop an importance sampling scheme for the simulation of quantum spin dynamics, building on a recent approach mapping quantum spin systems to classical stochastic processes. The importance sampling scheme is based on identifying the classical trajectory that yields the largest contribution to a given quantum observable. An exact transformation is then carried out to preferentially sample trajectories that are close to the dominant one. We demonstrate that this approach is capable of reducing the temporal growth of fluctuations in the stochastic quantities, thus extending the range of accessible times and system sizes compared to direct sampling. We discuss advantages and limitations of the proposed approach, outlining directions for further developments.Comment: Submission to SciPost, v2; 9 + 2 pages, 5 figure

The Future Concept of Work

This chapter offers a reappraisal of the idea of ‘personal work’ and a critical assessment of the concept of subordination, which shapes the traditional contract of employment and subordinate work. The authors suggest that the notion of personal work may be more useful in attempts to develop a newly conceptualised concept of human labour, one capable of incorporating certain dimensions of (unpaid) gendered labour, ‘heteromated’ labour (‘heteromation’ is the extraction of economic value from low-cost or free labour in computer-mediated networks), and other forms of socially (and ecologically) valuable labour that hitherto have been excluded from the realm of formal, protected and paid employment

Beyond the random phase approximation with a local exchange vertex

With the aim of constructing an electronic structure approach that systematically goes beyond the GW and random phase approximation (RPA) we introduce a vertex correction based on the exact-exchange (EXX) potential of time-dependent density functional theory. The EXX vertex function is constrained to be local but is expected to capture similar physics as the Hartree-Fock vertex. With the EXX vertex, we then unify different beyond-RPA approaches such as the various resummations of RPA with exchange and the second-order screened exchange approximation. The theoretical analysis is supported by numerical studies on the hydrogen dimer and the electron gas, and we discuss the role of including the vertex correction in both the screened interaction and the self-energy. Finally, we give details on our implementation within the plane-wave pseudo potential framework and demonstrate the excellent performance of the different RPA with exchange methods in describing the energetics of hydrogen and van der Waals bonds

The fundamental relation between supermassive black holes and their host galaxies

We study the correlations between supermassive black holes (BHs) and their host galaxies, using a sample of 83 BH masses collected from the most recent and reliable spatially resolved estimates available from the literature. We confirm the mono- and bivariate correlations between SMBHs and the bulges of their host galaxies, confirming that the correlation with the effective velocity dispersion is not significantly improved by higher dimensionality. Instead, pseudo-bulges do not seem to correlate with their SMBHs, probably because their secular evolution is often unable to trigger accretion onto the central BH. We then present a novel approach aimed at finding the fundamental relation between SMBHs and their host galaxies. For the first time, we analytically combine BH masses with the Fundamental Plane (FP), showing that M_(BH)–σ_e appears to be the fundamental relation rather than a putative ‘BH Fundamental Plane’ of the kind M_(BH)–σ_e–R_e. These results can be explained by a picture which sees the M_(BH)–σ_e relation as a natural outcome of the change in AGN feedback from momentum-driven to energy-driven. The other scaling relations are then established through the FP

The Fundamental Relation between Supermassive Black Holes and Their Host Galaxies

We study the correlations between Supermassive Black Holes (BH) and their host galaxies, using a sample of 83 BH masses collected from the most recent and reliable spatially resolved estimates available from the literature. We confirm the mono- and bivariate correlations between SMBHs and the bulges of their host galaxies, confirming that the correlation with the effective velocity dispersion is not significantly improved by higher dimensionality. Instead, pseudobulges do not seem to correlate with their SMBHs, probably because their secular evolution is often unable to trigger accretion onto the central BH. We then present a novel approach aimed at finding the fundamental relation between SMBHs and their host galaxies. For the first time, we analytically combine BH masses with the Fundamental Plane (FP), showing that Mbh-sigma_e appears to be the fundamental relation rather than a putative "BH Fundamental Plane" of the kind Mbh-sigma_e-R_e. These results can be explained by a picture which sees the Mbh-sigma_e relation as a natural outcome of the change in AGN feedback from momentum- to energy-driven. The other scaling relations are then established through the FP.Comment: 15 pages, 11 figures, accepted by MNRA

In-band label extractor based on Cascaded Si ring resonators enabling 160 Gb/s optical packet switching modules

Photonic integration of optical packet switching modules is crucial to compete with existing electronic switching fabrics in large data center networks. The approach of coding the forwarding packet information in an in-band label enables a spectral-efficient and scalable way of building low-latency large port count modular optical packet switching architecture. We demonstrate the error-free operation of the four in-band label extraction from 160 Gb/s optical data packets based on photonic integrated silicon-on- insulator ring resonators. Four low-loss cascaded ring resonators using the quasi-TM mode are used as narrowband filters to ensure the detection of four optical labels as well as the error-free forwarding of the payload at limited power penalty. Due to the low-loss and less-confined optical quasi-TM mode the resonators can be very narrowband and have low insertion loss. The effect of the bandwidth of the four ring resonators on the quality of the payload is investigated. We show that using four rings with 3dB bandwidth of 21 pm and only an insertion loss of 3 dB, the distortion on the payload is limited (< 1.5 dB power penalty), even when the resonances are placed very close to the packet's central wavelength. We also investigate the optical power requirements for error-free detection of the label as function of their spectral position relative to the center of the payload. The successful in-band positioning of the labels makes this component very scalable in amount of labels