Merging Protocol Research Articles

Evidence-based unification of potato gene models with the UniTato collaborative genome browser.

Potato (Solanum tuberosum) is the most popular tuber crop and a model organism. A variety of gene models for potato exist, and despite frequent updates, they are not unified. This hinders the comparison of gene models across versions, limits the ability to reuse experimental data without significant re-analysis, and leads to missing or wrongly annotated genes. Here, we unify the recent potato double monoploid v4 and v6 gene models by developing an automated merging protocol, resulting in a Unified poTato genome model (UniTato). We subsequently established an Apollo genome browser (unitato.nib.si) that enables public access to UniTato and further community-based curation. We demonstrate how the UniTato resource can help resolve problems with missing or misplaced genes and can be used to update or consolidate a wider set of gene models or genome information. The automated protocol, genome annotation files, and a comprehensive translation table are provided at github.com/NIB-SI/unitato.

A Reliable Wireless Protocol for Highway and Metered-Ramp CAV Collaborative Merging with Constant-Time-Headway Safety Guarantee

To realize the grand vision of automated driving in smart vehicle cyber-physical systems (CPS), one important task is to support the merging of connected automated vehicles (CAVs) from a metered-ramp to highway. Certain safety rules must be guaranteed. However, this demand is complicated by the inherently unreliable wireless communications. In this article, we focus on the well adopted constant-time-headway (CTH) safety rule. We propose a highway and metered-ramp CAV collaborative merging protocol, and formally prove its guarantee of the CTH safety and liveness under arbitrary wireless data packet losses . These theoretical claims are further validated by our simulations. Furthermore, the simulation results also show significant improvements in the merging efficiency over other solution alternatives. Particularly, the merging success rates are more than 99% better in 11 out of 18 comparison pairs, and 0% (i.e., tied) ∼ 71% better in the remaining 7 comparison pairs.

Graphical Animations of an Autonomous Vehicle Merging Protocol

Graphical Animations of an Autonomous Vehicle Merging Protocol

Entropy of a quantum channel

The von Neumann entropy of a quantum state is a central concept in physics and information theory, having a number of compelling physical interpretations. There is a certain perspective that the most fundamental notion in quantum mechanics is that of a quantum channel, as quantum states, unitary evolutions, measurements, and discarding of quantum systems can each be regarded as certain kinds of quantum channels. Thus, an important goal is to define a consistent and meaningful notion of the entropy of a quantum channel. Motivated by the fact that the entropy of a state $\rho$ can be formulated as the difference of the number of physical qubits and the "relative entropy distance" between $\rho$ and the maximally mixed state, here we define the entropy of a channel $\mathcal{N}$ as the difference of the number of physical qubits of the channel output with the "relative entropy distance" between $\mathcal{N}$ and the completely depolarizing channel. We prove that this definition satisfies all of the axioms, recently put forward in [Gour, IEEE Trans. Inf. Theory 65, 5880 (2019)], required for a channel entropy function. The task of quantum channel merging, in which the goal is for the receiver to merge his share of the channel with the environment's share, gives a compelling operational interpretation of the entropy of a channel. The entropy of a channel can be negative for certain channels, but this negativity has an operational interpretation in terms of the channel merging protocol. We define Renyi and min-entropies of a channel and prove that they satisfy the axioms required for a channel entropy function. Among other results, we also prove that a smoothed version of the min-entropy of a channel satisfies the asymptotic equipartition property.

Nonlinear Merging Consensus for Multi-Agent Systems on Directed and Weighted Signed Graph

This paper settles the nonlinear merging consensus for multi-agent systems on a directed and weighted signed network. A novel nonlinear merging control protocol is proposed to drive the states of all agents to arrive at the same state. To be consistent with the reality, the interactions among agents can be either cooperative or competitive and the information flow is considered to be directed. Particularly, the protocol can still ensure the states of all agents to reach an agreement, even though the corresponding directed network is not strongly connected. Besides, to guarantee the efficiency of multi-agent systems, the convergence rate of agents can be sped up by adjusting the parameter of the protocol. Finally, the theoretical analysis and simulation results are provided to verify the effectiveness of this protocol. The current results are instructive for us to comprehend and design an efficient consensus protocol within multi-agent systems.

Performance of a Partial Discrete Wavelet Transform Based Path Merging Compression Technique for Wireless Multimedia Sensor Networks

Wireless multimedia sensor network is well-known for its constraints in the field of multimedia processing in terms of processing power, bandwidth etc. Data processing is always a challenge in such network. Exploiting low overhead compression accompanied by proper routing and aggregation is a challenge for such energy starved multihop network. In this paper, we propose an efficient path merging protocol for wireless multimedia sensor network with randomly deployed nodes. Any partial discrete wavelet transform based compression technique can be plugged into this path merging protocol to reduce redundant data transmission in a significant manner by appropriate aggregation of data packets from merging paths. The design feasibility and the simulation results prove supremacy of our protocol over state-of-the-art competing schemes in terms of maintaining a trade-off between energy consumption and reconstruction quality.

An Evaluation of Four MODIS Collection 6 Aerosol Products in a Humid Subtropical Region

Moderate resolution imaging spectroradiometer (MODIS) aerosol optical depth (AOD) products have been widely used to characterize the temporal variations and spatial distributions of atmospheric aerosols. In the present study, we evaluate the performance of four Terra and Aqua MODIS Collection 6 (C6) quality assured AOD products in the Pearl River Delta (PRD) region, a humid subtropical region. The 10 km AOD products retrieved by the Dark Target (DT) and Deep Blue (DB) algorithms, the merged DT/DB (DTDB) 10 km product, and the DT 3 km AOD product were obtained for 2006–2015. These products were compared with Aerosol Robotic Network (AERONET) observations, and with each other. The Terra- and Aqua-derived AODs are quantitatively similar. However, there are significant differences among the four AOD products. The DT 10 km product correlates more closely with AERONET AOD observations than does the DB 10 km product. The latter tends to underestimate the AOD, whereas the former typically overestimates it for highly urbanized areas. The DTDB 10 km product is mainly derived from the DT 10 km product; it does not provide a gap-filled data set, because valid DB 10 km retrievals are not included in the merged product even when DT 10 km retrievals are unavailable. Therefore, the DT/DB merging protocol should be improved. The DT 3 km AOD product closely mimics the DT 10 km product; however, it contains fewer data than the DT 10 km product over water-contaminated areas. In addition, although the quality assured AOD products are recommended for use in quantitative applications by the MODIS aerosol science team, the sampling frequency of these products is generally lower than 25%. Thus, the sampling issues of these products should be considered in humid subtropical areas.

A nonlinear merging protocol for consensus in multi-agent systems on signed and weighted graphs

In this paper, we investigate the multi-agent consensus for networks with undirected graphs which are not connected, especially for the signed graph in which some edge weights are positive and some edges have negative weights, and the negative-weight graph whose edge weights are negative. We propose a novel nonlinear merging consensus protocol to drive the states of all agents to converge to the same state zero which is not dependent upon the initial states of agents. If the undirected graph whose edge weights are positive is connected, then the states of all agents converge to the same state more quickly when compared to most other protocols. While the undirected graph whose edge weights might be positive or negative is unconnected, the states of all agents can still converge to the same state zero under the premise that the undirected graph can be divided into several connected subgraphs with more than one node. Furthermore, we also discuss the impact of parameter r presented in our protocol. Current results can further deepen the understanding of consensus processes for multi-agent systems.

A Clean Slate Approach to Secure Ad Hoc Wireless Networking-Open Unsynchronized Networks

Distributed cyberphysical systems depend on secure wireless ad hoc networks to ensure that the sensors, controllers, and actuators (or nodes) in the system can reliably communicate. Such networks are difficult to design because, being inherently complex, they are vulnerable to attack. As a result, the current process of designing secure protocols for wireless ad hoc networks is effectively an arms race between discovering attacks and creating fixes. At no point in the process is it possible to make provable performance and security guarantees. This paper proposes a system-theoretic framework for the design of secure open wireless ad hoc networks, that provides precisely such guarantees. The nodes are initially unsynchronized, and join the network at any stage of the operation. The framework consists of a zero-sum game between all protocols and adversarial strategies, in which the protocol is announced before the adversarial strategy. Each choice of protocol and adversarial strategy results in a payoff. The design imperative is to choose the protocol that achieves the optimal payoff. We propose an “edge-tally supervised” merge protocol that is theoretically significant in three ways. First, the protocol achieves the max-min payoff; the highest possible payoff since the adversarial strategy always knows the protocol a priori . Second, the protocol actually does better and achieves the min-max payoff; it is a Nash equilibrium in the space of protocols and adversarial strategies. The adversarial nodes gain no advantage from knowing the protocol a priori . Third, the adversarial nodes are effectively limited to either jamming or conforming to the protocol; more complicated behaviors yield no strategic benefit.

Channel Simulation and Coded Source Compression

Coded source compression, also known as source compression with helpers, has been a major variant of distributed source compression, but has hitherto received little attention in the quantum regime. This work treats and solves the corresponding quantum coded source compression through an observation that connects coded source compression with channel simulation. First, we consider classical source coding with quantum side information where the quantum side information is observed by a helper and sent to the decoder via a classical channel. We derive a single-letter characterization of the achievable rate region for this problem. The direct coding theorem of our result is proved via the measurement compression theory of Winter, a quantum-to-classical channel simulation. Our result reveals that a helper's scheme which separately conducts a measurement and a compression is suboptimal, and measurement compression seems necessary to achieve the optimal rate region. We then study coded source compression in the fully quantum regime, where two different scenarios are considered depending on the types of communication channels between the legitimate source and the receiver. We further allow entanglement assistance from the quantum helper in both scenarios. We characterize the involved quantum resources, and derive single-letter expressions of the achievable rate region. The direct coding proofs are based on well-known quantum protocols, the quantum state merging protocol and the fully quantum Slepian-Wolf protocol, together with the quantum reverse Shannon theorem.

The Fail-Safe Operation of Collaborative Driving Systems

We consider the problem of collaborative driving systems in which the vehicles share sensor information and make joint decisions on vehicle control. Such a system involves vehicular control, communications links, and environment sensing. We propose a multiple stack architecture that is based on the nature of collaborative driving systems. The architecture facilitates the design, implementation, verification, and testing of a collaborative driving protocol. The advantage of using absolute time in a distributed system is also demonstrated. Specifically, we propose a merge protocol that assists a driver in merging with other vehicles based on the proposed architecture. We create a lock protocol and specify it as an extended finite state machine as a subroutine of the merge protocol. Absolute time simplifies a deadlock-free lock protocol. The lock protocol is verified using probabilistic verification.

Resource cost results for one-way entanglement distillation and state merging of compound and arbitrarily varying quantum sources

We consider one-way quantum state merging and entanglement distillation under compound and arbitrarily varying source models. Regarding quantum compound sources, where the source is memoryless, but the source state an unknown member of a certain set of density matrices, we continue investigations begun in the work of Bjelaković et al. [“Universal quantum state merging,” J. Math. Phys. 54, 032204 (2013)] and determine the classical as well as entanglement cost of state merging. We further investigate quantum state merging and entanglement distillation protocols for arbitrarily varying quantum sources (AVQS). In the AVQS model, the source state is assumed to vary in an arbitrary manner for each source output due to environmental fluctuations or adversarial manipulation. We determine the one-way entanglement distillation capacity for AVQS, where we invoke the famous robustification and elimination techniques introduced by Ahlswede. Regarding quantum state merging for AVQS we show by example that the robustification and elimination based approach generally leads to suboptimal entanglement as well as classical communication rates.

One-Shot Decoupling

If a quantum system A, which is initially correlated to another system, E, undergoes an evolution separated from E, then the correlation to E generally decreases. Here, we study the conditions under which the correlation disappears (almost) completely, resulting in a decoupling of A from E. We give a criterion for decoupling in terms of two smooth entropies, one quantifying the amount of initial correlation between A and E, and the other characterizing the mapping that describes the evolution of A. The criterion applies to arbitrary such mappings in the general one-shot setting. Furthermore, the criterion is tight for mappings that satisfy certain natural conditions. Decoupling has a number of applications both in physics and information theory, e.g., as a building block for quantum information processing protocols. As an example, we give a one-shot state merging protocol and show that it is essentially optimal in terms of its entanglement consumption/production.

Identifying the Information Gain of a Quantum Measurement

We show that quantum-to-classical channels, i.e., quantum measurements, can be asymptotically simulated by an amount of classical communication equal to the quantum mutual information of the measurement, if sufficient shared randomness is available. This result generalizes Winter's measurement compression theorem for fixed independent and identically distributed inputs [Winter, CMP 244 (157), 2004] to arbitrary inputs, and more importantly, it identifies the quantum mutual information of a measurement as the information gained by performing it, independent of the input state on which it is performed. Our result is a generalization of the classical reverse Shannon theorem to quantum-to-classical channels. In this sense, it can be seen as a quantum reverse Shannon theorem for quantum-to-classical channels, but with the entanglement assistance and quantum communication replaced by shared randomness and classical communication, respectively. The proof is based on a novel one-shot state merging protocol for "classically coherent states" as well as the post-selection technique for quantum channels, and it uses techniques developed for the quantum reverse Shannon theorem [Berta et al., CMP 306 (579), 2011].

Fundamental limitations to information transfer in accelerated frames

We study communication between an inertial observer and one of two causally disconnected counteraccelerating observers. We will restrict the quantum channel considering inertial-to-accelerated bipartite classical and quantum communication over different sets of Unruh modes (single-rail or dual-rail encoding). We find that the coherent information (and therefore the amount of entanglement that can be generated via state merging protocol) in this strongly restricted channel presents some interesting monogamy properties between the inertial and only one of the accelerated observers if we take a fixed choice of the Unruh mode used in the channel. The optimization of the controllable parameters is also studied and we find that they deviate from the values usually employed in the literature.

Interpreting quantum discord through quantum state merging

We present an operational interpretation of quantum discord based on the quantum state merging protocol. Quantum discord is the markup in the cost of quantum communication in the process of quantum state merging, if one discards relevant prior information. Our interpretation has an intuitive explanation based on the strong subadditivity of von Neumann entropy. We use our result to provide operational interpretations of other quantities like the local purity and quantum deficit. Finally, we discuss in brief some instances where our interpretation is valid in the single-copy scenario.

A scheme for increasing availability in partitioned replicated databases

We present a dynamic voting scheme that enhances the availability of data in a replicated database system in the presence of network partitions. When a network partition occurs, the distributed system splits into several groups such that nodes in one group cannot communicate with nodes in another group. In such situations, the proposed scheme maintains consistency of replicated data by imposing the following constraint: a node can update only if its current enclosing group is a majority of its previous enclosing group. Thus, the number of nodes that constitutes a majority is reduced dynamically upon successive partitions. A distinguishing aspect of the proposed scheme is that each node maintains its view of the network and keeps track of partitions that occur between successive update transactions. This technique minimizes the situations in which no group can perform an update. Another interesting feature of the proposed scheme is that it does not require failures and repairs of links and nodes to be detected instantaneously by all nodes. Different nodes may have different views of the network at any time. This introduces complications when partitions merge, and we present a merge protocol that takes this into account. We also outline a correctness proof for our proposed scheme.