Simple and Efficient Local Codes for Distributed Stable Network Construction

In this work, we study protocols so that populations of distributed processes can construct networks. In order to highlight the basic principles of distributed network construction we keep the model minimal in all respects. In particular, we assume finite-state processes that all begin from the same initial state and all execute the same protocol (i.e. the system is homogeneous). Moreover, we assume pairwise interactions between the processes that are scheduled by an adversary. The only constraint on the adversary scheduler is that it must be fair. In order to allow processes to construct networks, we let them activate and deactivate their pairwise connections. When two processes interact, the protocol takes as input the states of the processes and the state of the their connection and updates all of them. Initially all connections are inactive and the goal is for the processes, after interacting and activating/deactivating connections for a while, to end up with a desired stable network. We give protocols (optimal in some cases) and lower bounds for several basic network construction problems such as spanning line, spanning ring, spanning star, and regular network. We provide proofs of correctness for all of our protocols and analyze the expected time to convergence of most of them under a uniform random scheduler that selects the next pair of interacting processes uniformly at random from all such pairs. Finally, we prove several universality results by presenting generic protocols that are capable of simulating a Turing Machine (TM) and exploiting it in order to construct a large class of networks.Comment: 43 pages, 7 figure

Cost-based Management and Decision Making in Greek Luxury Hotels

The use of cost accounting systems by hotel businesses is improving the quality of decision making. The development of theories on costing, combined with advances in information technology, has improved the theoretical capabilities of such systems. However, two questions remain largely unanswered: a) whether these theories lead to tangible improvements; and b) what are the variables that drive the success of cost accounting systems. Our research shows that hotel managers need to be convinced about the use and performance benefits of such systems in the decision making process.Cost Accounting, Decision Making, Luxury Hotels, Greece

Distributed Massive MIMO in Cellular Networks: Impact of Imperfect Hardware and Number of Oscillators

Distributed massive multiple-input multiple-output (MIMO) combines the array gain of coherent MIMO processing with the proximity gains of distributed antenna setups. In this paper, we analyze how transceiver hardware impairments affect the downlink with maximum ratio transmission. We derive closed-form spectral efficiencies expressions and study their asymptotic behavior as the number of the antennas increases. We prove a scaling law on the hardware quality, which reveals that massive MIMO is resilient to additive distortions, while multiplicative phase noise is a limiting factor. It is also better to have separate oscillators at each antenna than one per BS.Comment: First published in the Proceedings of the 23rd European Signal Processing Conference (EUSIPCO-2015) in 2015, published by EURASIP. 5 pages, 3, figure

The IAS 8 analysis and critical thesis of the IAS 8

In this paper the concept and the solutions suggested by IAS 8 are analysed extensively by using accounting examples. These solutions are indicated in order to achieve a equable treatment of the issues that this standard introduces in accounting. In the first part the definitions of the Standard are presented and the meanings of net profit or loss are clarified. Net profit or loss comes either from enterprise’s ordinary activities or from activities of extraordinary nature the result of whom forms extraordinary results. Afterwards, the accounting errors are mentioned and the way to correct them is indicated using recent accounting examples. Moreover, in this paper are mentioned the notifications that must be made in order to ensure the reliability of the economic conditions. Finally, the accounting treatment of the changes in accounting policies is made clear. These changes are described explicitly by using examples of economic conditions.peer-reviewe

M-mappings and the cellularity of spaces

AbstractIt is shown that an image X of a product of Lindelöf Σ-spaces or of a countably compact (even countably protocompact) space Π under a continuous M-mapping is ℵ0-cellular in the sense of A.V. Arhangel'skiĭ. The same holds if both Π and X have “good” lattices of continuous mappings. Some generalizations of earlier results of V.V. Uspenskiǐ and M.G. Tkačenko on continuous images of (dense subspaces of) topological groups are also given