Characterizing graph symmetries through quantum Jensen-Shannon divergence

In this paper we investigate the connection between quantum walks and graph symmetries. We begin by designing an experiment that allows us to analyze the behavior of the quantum walks on the graph without causing the wave function collapse. To achieve this, we base our analysis on the recently introduced quantum Jensen-Shannon divergence. In particular, we show that the quantum Jensen-Shannon divergence between the evolution of two quantum walks with suitably defined initial states is maximum when the graph presents symmetries. Hence, we assign to each pair of nodes of the graph a value of the divergence, and we average over all pairs of nodes to characterize the degree of symmetry possessed by a graph. © 2013 American Physical Society.

A quantum Jensen-Shannon graph kernel using the continuous-time quantum walk

In this paper, we use the quantum Jensen-Shannon divergence as a means to establish the similarity between a pair of graphs and to develop a novel graph kernel. In quantum theory, the quantum Jensen-Shannon divergence is defined as a distance measure between quantum states. In order to compute the quantum Jensen-Shannon divergence between a pair of graphs, we first need to associate a density operator with each of them. Hence, we decide to simulate the evolution of a continuous-time quantum walk on each graph and we propose a way to associate a suitable quantum state with it. With the density operator of this quantum state to hand, the graph kernel is defined as a function of the quantum Jensen-Shannon divergence between the graph density operators. We evaluate the performance of our kernel on several standard graph datasets from bioinformatics. We use the Principle Component Analysis (PCA) on the kernel matrix to embed the graphs into a feature space for classification. The experimental results demonstrate the effectiveness of the proposed approach. © 2013 Springer-Verlag.

Attributed graph similarity from the quantum Jensen-Shannon divergence

One of the most fundamental problem that we face in the graph domain is that of establishing the similarity, or alternatively the distance, between graphs. In this paper, we address the problem of measuring the similarity between attributed graphs. In particular, we propose a novel way to measure the similarity through the evolution of a continuous-time quantum walk. Given a pair of graphs, we create a derived structure whose degree of symmetry is maximum when the original graphs are isomorphic, and where a subset of the edges is labeled with the similarity between the respective nodes. With this compositional structure to hand, we compute the density operators of the quantum systems representing the evolution of two suitably defined quantum walks. We define the similarity between the two original graphs as the quantum Jensen-Shannon divergence between these two density operators, and then we show how to build a novel kernel on attributed graphs based on the proposed similarity measure. We perform an extensive experimental evaluation both on synthetic and real-world data, which shows the effectiveness the proposed approach. © 2013 Springer-Verlag.

A stable graph-based representation for object recognition through high-order matching

Many Object recognition techniques perform some flavour of point pattern matching between a model and a scene. Such points are usually selected through a feature detection algorithm that is robust to a class of image transformations and a suitable descriptor is computed over them in order to get a reliable matching. Moreover, some approaches take an additional step by casting the correspondence problem into a matching between graphs defined over feature points. The motivation is that the relational model would add more discriminative power, however the overall effectiveness strongly depends on the ability to build a graph that is stable with respect to both changes in the object appearance and spatial distribution of interest points. In fact, widely used graph-based representations, have shown to suffer some limitations, especially with respect to changes in the Euclidean organization of the feature points. In this paper we introduce a technique to build relational structures over corner points that does not depend on the spatial distribution of the features. © 2012 ICPR Org Committee.

Supervised learning of graph structure

Graph-based representations have been used with considerable success in computer vision in the abstraction and recognition of object shape and scene structure. Despite this, the methodology available for learning structural representations from sets of training examples is relatively limited. In this paper we take a simple yet effective Bayesian approach to attributed graph learning. We present a naïve node-observation model, where we make the important assumption that the observation of each node and each edge is independent of the others, then we propose an EM-like approach to learn a mixture of these models and a Minimum Message Length criterion for components selection. Moreover, in order to avoid the bias that could arise with a single estimation of the node correspondences, we decide to estimate the sampling probability over all the possible matches. Finally we show the utility of the proposed approach on popular computer vision tasks such as 2D and 3D shape recognition. © 2011 Springer-Verlag.

Social Recommendation Based on Content and Trust

Report published in the Proceedings of the National Conference on "Education and Research in the Information Society", Plovdiv, May, 2014

Uneasy lies the head that bears the trust:the effects of feeling trusted on emotional exhaustion

The construct of feeling trusted reflects the perception that another party is willing to accept vulnerability to one's actions. Although this construct has received far less attention than trusting, the consensus is that believing their supervisors trust them has benefits for employees' job performance. Our study challenges that consensus by arguing that feeling trusted can be exhausting for employees. Drawing on Stevan Hobfoll's conservation of resources theory, we develop a model in which feeling trusted fills an employee with pride a benefit for exhaustion and performance while also increasing perceived workload and concerns about reputation maintenance burdens for exhaustion and performance. We test our model in a field study using a sample of public transit bus drivers in London, England. Our results suggest that feeling trusted is a double-edged sword for job performance, bringing with it both benefits and burdens. Given that recommendations for managers generally encourage placing trust in employees, these results have important practical implications.

Leader trustworthy behavior and organizational trust:the role of the immediate manager for cultivating trust

Drawing from both trust-building theory and interpersonal trust literature, we investigate how trust between a leader and follower may be leveraged to influence organizational trust. We also explore the mediating mechanisms of this link and test a potential moderator. A cross-sectional, multi-foci design was adopted and participants were 201 employees within a public sector organization. Leader trustworthy behavior was found to predict organizational trust, mediated by trustworthiness perceptions and trust in the leader. Support for the boundary condition was found; namely, when leaders were more senior, the relationship between trustworthy behavior and organizational trust was stronger. The findings suggest that leaders can meaningfully influence organizational trust perceptions through the enactment of trustworthy behavior, although the strength of this effect varied as a function of their position.

A fogyasztói lojalitás előzményei a magyar mobiltelefonos szolgáltatási piacon – A bizalom szerepe (Antecedents of the consumer loyalty in the Hungarian telecommunication market – the role of trust)

A fogyasztói lojalitás kritikus versenyelőnynek számít a szolgáltatóknak a telekommunikációs szektorban, ahol a piac növekedésének lassulásával és az erősödő piaci verseny folytán a vállalatoknak inkább a fogyasztók megtartására kell fókuszálniuk. Egyre fontosabbá vált és válik a piaci részesedés, illetve a már meglévő ügyfelek megtartása, mivel az új ügyfelek megszerzésének költsége és nehézsége is megnőtt. Az ügyfelek megtartásához ki kell vívni a hosszú távú kapcsolat fenntartását, vagyis a fogyasztók lojalitását. A korábbi marketing-irodalomban a fogyasztók elégedettségének szerepe a lojalitás kialakításában vitathatatlan, azonban felmerül a kérdés, hogy mennyire közvetlen ez a hatás. Így érdemes megvizsgálni, mint közvetítő változónak az elégedettség és lojalitás között, a fogyasztói bizalom szerepét is a fogyasztói lojalitás formálódásában. A szerző empirikus kutatásának eredményei azt támasztják alá, hogy a fogyasztói elégedettség hatása a fogyasztói lojalitásra nem feltétlenül közvetlen, hanem a fogyasztói bizalom játszik közvetítő szerepet, és a bizalom a fogyasztói lojalitás erősebb indikátorának bizonyult, mint egyedül az elégedettség. / === / The consumer loyalty is a crucial competitive advantage in the telecommunication sector, which has a decreasing growth rate and increasing market competition, so the companies should focus on the consumer retention. The market share and the retention of present consumers become more and more important, because both the cost and the difficulty of the acquisition of new consumers are increased. The previous marketing literature states that the role of satisfaction in loyalty is evident, but the effect is not necessary a direct one. Worth to examine the role of consumer trust in loyalty creation, where trust is a mediator variable between satisfaction and loyalty. The author’s empirical results suggest the direct effect of satisfaction on loyalty is not necessary direct, but indirect, where the consumer trust is the link. The effect of trust on loyalty is higher than the satisfaction alone.

Bizalom és kockázat a kapcsolatokban – egy kísérlet eredményei = Relationship between trust and risk - results of an experiment

Műhelytanulmányunkban a diadikus kapcsolatokat állítjuk az elemzés középpontjába. A Budapesti Corvinus Egyetem másodéves, gazdálkodástudományi alapszakjaira járó hallgatóiból véletlenszerűen alakított kétoldalú kapcsolatokban a felek egymás iránt érzett bizalmi szintje és különböző szintű kockázat melletti konkrét cselekvése közötti kapcsolatot vizsgáltuk. Előzetes várakozásaink szerint a felek egymás iránt érzett bizalmi szintje befolyásolja, hogy különböző kockázati szintek mellett hogyan fognak a kapcsolatban szereplő egyének viselkedni. Empirikus elemzésünk során a közgazdaságtanban is elfogadott kísérlet eszközét választottuk, s konkrét adatainkat, megfigyeléseinket e módszertannal gyűjtöttük össze. Az így kapott mintát a Magyarországon a gazdálkodás-, illetve közgazdaságtudományban tudomásunk szerint eddig még nem használt diadikus adatelemzés speciális statisztikai módszertanát alkalmazva vizsgáltuk. Műhelytanulmányunk célja volt ezért az is, hogy ennek a hálózati gazdaság építőkövének, a kapcsolatnak a vizsgálatára alkalmas elemzési módszertannak az ismertetését is megtegyük. _______ In the working paper we have focused on the analysis of trust in dyadic relationships. We have assumed that trust is a kind of coordinating mechanism in these relationships, the existence of which influences interaction between dyadic partners. We carried out an experiment with the help of bachelor students studying at the Budapest Corvinus University. Our hypothesis was that medium and high level of trust will influence the willingness to take more risky decisions. These experiments have been realized in concrete personal dyads; therefore the applied statistical analysis was the dyadic analysis that is a new analytical method developed for analyzing such dyadic problem settings.

Trust and cooperation in buyer–seller relationships and networks. The co-evolution of structural balance and trust in iterated PD games

Our study has two aims: to elaborate theoretical frameworks and introduce social mechanisms of spontaneous co-operation in repeated buyer-seller relationships and to formulate hypotheses which can be empirically tested. The basis of our chain of ideas is the simple two-person Prisoner’s Dilemma game. On the one hand, its repeated variation can be applicable for the distinction of the analytical types of trust (iteration trust, strategy trust) in co-operations. On the other hand, it provides a chance to reveal those dyadic sympathy-antipathy relations, which make us understand the evolution of trust. Then we introduce the analysis of the more complicated (more than two-person) buyer-seller relationship. Firstly, we outline the possible role of the structural balancing mechanisms in forming trust in three-person buyer-seller relationships. Secondly, we put forward hypotheses to explain complex buyer-seller networks. In our research project we try to theoretically combine some of the simple concepts of game theory with certain ideas of the social-structural balance theory. Finally, it is followed by a short summary.

A tranzakciós költségek elmélete és a társadalmi csereelmélet hatásai a bizalomra az ellátási láncban (Affects of Transaction cost and Social Exchange Constructs on trust In supply chain relationship)

A szerzők alapvető feltételezése, hogy az ellátási láncban a bizalom ösztönzi a felek közötti elkötelezettséget. Továbbá a bizalom növeli annak a lehetőségét, hogy az ellátási lánc sikeresen működjön. Ugyanakkor, a felek közötti bizalom hiánya gyakran megnöveli a tranzakciós költségeket, és így csökkenti a hatékonyságot. A cikkben bemutatott kutatás adatgyűjtésére több országban – Franciaországban, Magyarországon, Dél-Koreában, Tunéziában és az Egyesült Államokban – került sor. Összesen 729 érvényes kérdőív érkezett vissza, amelyeket a különböző ellátási láncok résztvevői töltöttek ki. A kutatási eredmények szerint az ellátási láncokon belüli üzleti kapcsolatokban a tranzakciós költségek elméletének összetevői (kapcsolatspecifikusság és viselkedési bizonytalanság), valamint a társadalmi csereelmélet tényezői (lecserélhetőség, észlelt megelégedettség, a partner hírneve és észlelt konfliktus) szoros kapcsolatban állnak a bizalom és az elkötelezettség változóival. _____ This article is based on the assumption that trust promotes commitment between partners in the supply chain and improves the chances of return on supply chain success. In contrast, a lack of trust between them often increases transaction costs and results in inefficiency. The results of this research, based on multi-country surveys with 729 returns from France, Hungary, Korea, Tunisia and the United States on supply chain professionals, reveals a strong affect of transaction cost constructs (TCC) (asset specificity and behavioral uncertainty) and social exchange constructs (SEC) (replaceability, perceived satisfaction, partner reputation, and perceived conflict) on trust-commitment variables in partnership based supply chain relationships. This paper employed a structural equation model to extract information from the survey data. Among the findings, the research indicates that a firm’s trustcommitment in dealing with their supply chain partnership is highly associated with not only transaction cost, but more so with social exchange variables. This study may open a new research avenue in that there is another construct, SEC, beside TSC that influences the degree of trust and commitment.

Trust - Networking - Innovation

From innovation point of view the agri-food industry is seen as matured branch of the economy, where revolutionary new products and processes are very rare. Especially the SMEs are in squeezing situation: they have to fit very sharp prerequisites and demands on one side and very much constrained resources to give them power in order to formulate appropriate answers on the other side. They are looking for partners beyond the boundaries of their organization, mainly with other firms, universities, research organisations and government agencies. Adopting an effective innovation process to successfully introduce and develop new products to the market has become one of the most important strategies for food companies. The innovation dimension of networking activity contributes to growing network complexity, which in turn also affects the nature of traditional governance structure. Trust and other relational factors are playing an increasing role in these structures. Our research interest is whether the trust as coordination form of governance structure plays significant role in the Hungarian agri-food industry. Empirical data was drawn from a survey carried out in Central Hungary and aiming at the research of cooperation and knowledge management within the SMEs of the food economy. Structural Equation Modelling (SEM) is applied in order to determine the relationship among the three (Trust, Networking, Innovation) latent factors. We have found that trust plays significant positive role in increasing networking activity and innovation, but the extent of it is less than expected.

How trust affects the use of information obtained through intra- and extraorganizational relationships?

We have limited knowledge on the potential pattern similarities/differences of trust’s role that may exist in information use obtained through intra- and extra-organizational relationships. This study addresses this question by investigating how trust leads to information use. Data from 338 intra-organizational and a sub-ample of 158 interorganizational dyadic information exchange-relationships showed that trust is an important driver of the utilization of market information in both cases. Trust has no direct relationship to information use, instead has a strong indirect effect through a mediator, perceived quality of information. The effects of trust on the use of information obtained through inter- and extra-organizational dyadic relationships proved to be similar.