Liyin Xue

Conflict control locking in distributed cooperative graphics editors

Communication latency presents a major challenge to achieving high responsiveness for Internet based cooperative editing systems. The authors propose conflict control locking (post-locking) schemes for conflict resolution in real time object based cooperative graphics editors. With these schemes, no locking request is needed before applying an editing operation to an object, instead, a lock will automatically be generated by the system if a conflict occurs. Lock ownership assigning rules are devised for the schemes. With a specific post-locking approach, algorithms and implementation techniques such as lock synchronisation detection, voting, and group intention realisation, are discussed in detail.

Quantum direct secret sharing with efficient eavesdropping-check and authentication based on distributed fountain codes

We propose to use a simple and effective way to achieve secure quantum direct secret sharing. The proposed scheme uses the properties of fountain codes to allow a realization of the physical conditions necessary for the implementation of no-cloning principle for eavesdropping-check and authentication. In our scheme, to achieve a variety of security purposes, nonorthogonal state particles are inserted in the transmitted sequence carrying the secret shares to disorder it. However, the positions of the inserted nonorthogonal state particles are not announced directly, but are obtained by sending degrees and positions of a sequence that are pre-shared between Alice and each Bob. Moreover, they can confirm that whether there exists an eavesdropper without exchanging classical messages. Most importantly, without knowing the positions of the inserted nonorthogonal state particles and the sequence constituted by the first particles from every EPR pair, the proposed scheme is shown to be secure.

Fault-tolerant high-capacity quantum key distribution over a collective-noise channel using extended unitary operations

We propose two fault-tolerant high-capacity quantum key distribution schemes, in which an entangled pair over a collective-noise channel consisting of one logical qubit and one physical qubit can carry four bits of key information. The basic idea is to use 2-extended unitary operations from collective noises together with quantum dense coding. The key messages are encoded on logical qubits of two physical qubits with sixteen 2-extended unitary operations based on collective noises. The key can be recovered using Bell-state analysis on the logical qubit and a single-photon measurement on the physical qubit rather than three-qubit GHZ joint measurements. The proposed protocols require a collation table to be shared between Alice and Bob in advance. Consequently, the key messages carried by an entangled state, in our protocol, have doubled at the price of sharing the collation table between Alice and Bob. However, the efficiency of qubits is enhanced because a quantum bit is more expensive to prepare than a classical bit.

A Multi-Versioning Scheme for Intention Preservation in Collaborative Editing Systems*

Although the multi-version approach to consistency maintenance has been widely discussed and implemented in database systems, version control systems, and asynchronous groupware systems, its potential in real-time groupware systems is largely unexplored. Intention preservation is an important aspect of consistency maintenance in real-time collaborative editing systems, where multiple users cooperate with each other by concurrently editing the same document. The multi-version approach is supposed to be able to preserve individual users’ concurrent conflicting intentions. In this article, we propose a new multi-versioning scheme that can preserve not only concurrent conflicting intentions but also contextual intentions while achieving convergence of the document under editing. By extending an existing multi-versioning scheme to a general one that specifies the conditions for convergence, we decouple the discussion of convergence from that of intention preservation. By constraining the general scheme, we arrive at the novel scheme that guarantees to preserve users’ intentions. The correctness of the scheme has been formally verified. The design of an algorithm for consistent version composition and identification has been discussed in detail.

From Predefined Consistency to User-Centered Emergent Consistency in Real-Time Collaborative Editing Systems

In this paper, we introduce a basic conceptual model of real-time collaborative editing systems which differentiates the coordination aspect of actions (which do not exist in single-user systems) from the application-dependent semantic aspect of actions (i.e., those actions that happen in single-user systems). Based on this model, a new taxonomy is provided to analyze the existing consistency-maintenance mechanisms and highlight potential new mechanisms. Furthermore, a new user-centered consistency model is proposed, which focuses on dynamic consistency that is negotiable among end users rather than static consistency that is automatically determined by the system. In the mean time, some challenging research issues in real-time collaborative editing systems are outlined

The Impact of Discrimination on the Spread of Infectious Diseases in Complex Networks

This paper proposes a novel model combining an epidemic dynamics and an opinion dynamics to investigate the impact of epidemic-related opinion dynamics on the spreading of infectious diseases in complex networks. We assume that, the outcomes of opinion dynamics on the behavior of asymptomatically infected individuals who have known their infected state, could not only reduce their transmission probabilities, but also could increase their transmission probabilities. This assumption has rarely been considered for modeling the interactions among epidemic dynamics, opinion dynamics and the exchange of human behaviors. We find that when the epidemic-related opinion dynamics exist, a higher randomness of individuals will simultaneously lead to a higher prevalence of infectious diseases and a lower social discrimination perceived by infected individuals. Furthermore, if the positive external global impact exceeds a certain critical value, there is an abrupt disappearance of infection owing to the contribution of opinion dynamics. Based on our results, some suggestions are given to reduce the spreading of epidemic diseases.

An Engagement Model Based on User Interest and QoS in Video Streaming Systems

With the surging demand on high-quality mobile video services and the unabated development of new network technology, including fog computing, there is a need for a generalized quality of user experience (QoE) model that could provide insight for various network optimization designs. A good QoE, especially when measured as engagement, is an important optimization goal for investors and advertisers. Therefore, many works have focused on understanding how the factors, especially quality of service (QoS) factors, impact user engagement. However, the divergence of user interest is usually ignored or deliberatively decoupled from QoS and/or other objective factors. With an increasing trend towards personalization applications, it is necessary as well as feasible to consider user interest to satisfy aesthetic and personal needs of users when optimizing user engagement. We first propose an Extraction-Inference (E-I) algorithm to estimate the user interest from easily obtained user behaviors. Based on our empirical analysis on a large-scale dataset, we then build a QoS and user Interest based Engagement (QI-E) regression model. Through experiments on our dataset, we demonstrate that the proposed model reaches an improvement in accuracy by 9.99% over the baseline model which only considers QoS factors. The proposed model has potential for designing QoE-oriented scheduling strategies in various network scenarios, especially in the fog computing context.

A hybrid quantum key distribution protocol based on extended unitary operations and fountain codes

In 1984, Bennett and Brassard designed the first quantum key distribution protocol, whose security is based on quantum indeterminacy. Since then, there has been growing research activities, aiming in designing new, more efficient and secure key distribution protocols. The work presents a novel hybrid quantum key distribution protocol. The key distribution is derived from both quantum and classical data. This is why it is called hybrid. The protocol applies extended unitary operations derived from four basic unitary operations and distributed fountain codes. Compared to other protocols published so far, the new one is more secure (provides authentication of parties and detection of eavesdropping) and efficient. Moreover, our protocol still works over noisy and lossy channels.