scholarly journals From Recommendation Systems to Facility Location Games

2019 ◽  
Vol 33 ◽  
pp. 1772-1779
Author(s):  
Omer Ben-Porat ◽  
Gregory Goren ◽  
Itay Rosenberg ◽  
Moshe Tennenholtz
Keyword(s):  
Social Welfare ◽  
Facility Location ◽  
Recommendation Systems ◽  
Semantic Space ◽  
Open Questions ◽  
Intervention Cost ◽  
Equilibrium Profile ◽  
Location Games ◽  
Facility Location Models ◽  
The One

Recommendation systems are extremely popular tools for matching users and contents. However, when content providers are strategic, the basic principle of matching users to the closest content, where both users and contents are modeled as points in some semantic space, may yield low social welfare. This is due to the fact that content providers are strategic and optimize their offered content to be recommended to as many users as possible. Motivated by modern applications, we propose the widely studied framework of facility location games to study recommendation systems with strategic content providers. Our conceptual contribution is the introduction of a mediator to facility location models, in the pursuit of better social welfare. We aim at designing mediators that a) induce a game with high social welfare in equilibrium, and b) intervene as little as possible. In service of the latter, we introduce the notion of intervention cost, which quantifies how much damage a mediator may cause to the social welfare when an off-equilibrium profile is adopted. As a case study in high-welfare low-intervention mediator design, we consider the one-dimensional segment as the user domain. We propose a mediator that implements the socially optimal strategy profile as the unique equilibrium profile, and show a tight bound on its intervention cost. Ultimately, we consider some extensions, and highlight open questions for the general agenda.

scholarly journals Two-Stage Facility Location Games with Strategic Clients and Facilities

2021 ◽  
Author(s):  
Simon Krogmann ◽  
Pascal Lenzner ◽  
Louise Molitor ◽  
Alexander Skopalik
Keyword(s):  
Facility Location ◽  
Waiting Time ◽  
Price Of Anarchy ◽  
Price Of Stability ◽  
Client Behavior ◽  
Game Theoretic ◽  
Location Games ◽  
Facility Location Models ◽  
Subgame Perfect Equilibria ◽  
Perfect Equilibria

We consider non-cooperative facility location games where both facilities and clients act strategically and heavily influence each other. This contrasts established game-theoretic facility location models with non-strategic clients that simply select the closest opened facility. In our model, every facility location has a set of attracted clients and each client has a set of shopping locations and a weight that corresponds to its spending capacity. Facility agents selfishly select a location for opening their facility to maximize the attracted total spending capacity, whereas clients strategically decide how to distribute their spending capacity among the opened facilities in their shopping range. We focus on a natural client behavior similar to classical load balancing: our selfish clients aim for a distribution that minimizes their maximum waiting time for getting serviced, where a facility’s waiting time corresponds to its total attracted client weight. We show that subgame perfect equilibria exist and we give almost tight constant bounds on the Price of Anarchy and the Price of Stability, which even hold for a broader class of games with arbitrary client behavior. Since facilities and clients influence each other, it is crucial for the facilities to anticipate the selfish clients’ behavior when selecting their location. For this, we provide an efficient algorithm that also implies an efficient check for equilibrium. Finally, we show that computing a socially optimal facility placement is NP-hard and that this result holds for all feasible client weight distributions.

Combinatorial principles weaker than Ramsey's Theorem for pairs

2007 ◽  
Vol 72 (1) ◽  
pp. 171-206 ◽  
Author(s):  
Denis R. Hirschfeldt ◽  
Richard A. Shore
Keyword(s):  
Reverse Mathematics ◽  
The Other ◽  
Base System ◽  
Ramsey's Theorem ◽  
Open Questions ◽  
Ramsey’S Theorem ◽  
Combinatorial Principles ◽  
Points Of View ◽  
The One ◽  
Infinite Linear

AbstractWe investigate the complexity of various combinatorial theorems about linear and partial orders, from the points of view of computability theory and reverse mathematics. We focus in particular on the principles ADS (Ascending or Descending Sequence), which states that every infinite linear order has either an infinite descending sequence or an infinite ascending sequence, and CAC (Chain-AntiChain), which states that every infinite partial order has either an infinite chain or an infinite antichain. It is wellknown that Ramsey's Theorem for pairs () splits into a stable version () and a cohesive principle (COH). We show that the same is true of ADS and CAC, and that in their cases the stable versions are strictly weaker than the full ones (which is not known to be the case for and ). We also analyze the relationships between these principles and other systems and principles previously studied by reverse mathematics, such as WKL0, DNR, and BΣ2. We show, for instance, that WKL0 is incomparable with all of the systems we study. We also prove computability-theoretic and conservation results for them. Among these results are a strengthening of the fact, proved by Cholak, Jockusch, and Slaman, that COH is -conservative over the base system RCA0. We also prove that CAC does not imply DNR which, combined with a recent result of Hirschfeldt, Jockusch. Kjos-Hanssen, Lempp, and Slaman, shows that CAC does not imply (and so does not imply ). This answers a question of Cholak, Jockusch, and Slaman.Our proofs suggest that the essential distinction between ADS and CAC on the one hand and on the other is that the colorings needed for our analysis are in some way transitive. We formalize this intuition as the notions of transitive and semitransitive colorings and show that the existence of homogeneous sets for such colorings is equivalent to ADS and CAC, respectively. We finish with several open questions.

Facility location models for immobile servers with stochastic demand

2003 ◽  
Vol 51 (1) ◽  
pp. 137-152 ◽  
Author(s):  
Qian Wang ◽  
Rajan Batta ◽  
Christopher M. Rump
Keyword(s):  
Facility Location ◽  
Stochastic Demand ◽  
Location Models ◽  
Facility Location Models

A New Collaborative Filtering Approach Based on Game Theory for Recommendation Systems

2021 ◽  
Author(s):  
Selma Benkessirat ◽  
Narhimene Boustia ◽  
Rezoug Nachida
Keyword(s):  
Game Theory ◽  
Collaborative Filtering ◽  
Cooperative Game ◽  
Shapley Value ◽  
Cooperative Game Theory ◽  
Recommendation Systems ◽  
Internet Users ◽  
User Communities ◽  
The One

Recommendation systems can help internet users to find interesting things that match more with their profile. With the development of the digital age, recommendation systems have become indispensable in our lives. On the one hand, most of recommendation systems of the actual generation are based on Collaborative Filtering (CF) and their effectiveness is proved in several real applications. The main objective of this paper is to improve the recommendations provided by collaborative filtering using clustering. Nevertheless, taking into account the intrinsic relationship between users can enhance the recommendations performances. On the other hand, cooperative game theory techniques such as Shapley Value, take into consideration the intrinsic relationship among users when creating communities. With that in mind, we have used SV for the creation of user communities. Indeed, our proposed algorithm preforms into two steps, the first one consists to generate communities user based on Shapley Value, all taking into account the intrinsic properties between users. It applies in the second step a classical collaborative filtering process on each community to provide the Top-N recommendation. Experimental results show that the proposed approach significantly enhances the recommendation compared to the classical collaborative filtering and k-means based collaborative filtering. The cooperative game theory contributes to the improvement of the clustering based CF process because the quality of the users communities obtained is better.

Network facility-location models in Stackelberg-Nash-Cournot spatial competition

1992 ◽  
Vol 71 (3) ◽  
pp. 277-291 ◽  
Author(s):  
Tan Miller ◽  
Roger L. Tobin ◽  
Terry L. Friesz
Keyword(s):  
Facility Location ◽  
Spatial Competition ◽  
Location Models ◽  
Facility Location Models

scholarly journals Non-Cooperative Facility Location Games: a Survey

2017 ◽  
Vol 24 (1) ◽  
pp. 59 ◽  
Author(s):  
Félix Carvalho Rodrigues ◽  
Eduardo Xavier
Keyword(s):  
Facility Location ◽  
Location Games

scholarly journals There Is No Logical Negation Here, But There Are Alternatives: Modeling Conversational Negation with Distributional Semantics

2016 ◽  
Vol 42 (4) ◽  
pp. 637-660 ◽  
Author(s):  
Germán Kruszewski ◽  
Denis Paperno ◽  
Raffaella Bernardi ◽  
Marco Baroni
Keyword(s):  
Large Data ◽  
Semantic Space ◽  
The Other ◽  
Similarity Function ◽  
Distributional Semantics ◽  
Application Domain ◽  
Data Set ◽  
Logical Negation ◽  
The One ◽  
The Right

Logical negation is a challenge for distributional semantics, because predicates and their negations tend to occur in very similar contexts, and consequently their distributional vectors are very similar. Indeed, it is not even clear what properties a “negated” distributional vector should possess. However, when linguistic negation is considered in its actual discourse usage, it often performs a role that is quite different from straightforward logical negation. If someone states, in the middle of a conversation, that “This is not a dog,” the negation strongly suggests a restricted set of alternative predicates that might hold true of the object being talked about. In particular, other canids and middle-sized mammals are plausible alternatives, birds are less likely, skyscrapers and other large buildings virtually impossible. Conversational negation acts like a graded similarity function, of the sort that distributional semantics might be good at capturing. In this article, we introduce a large data set of alternative plausibility ratings for conversationally negated nominal predicates, and we show that simple similarity in distributional semantic space provides an excellent fit to subject data. On the one hand, this fills a gap in the literature on conversational negation, proposing distributional semantics as the right tool to make explicit predictions about potential alternatives of negated predicates. On the other hand, the results suggest that negation, when addressed from a broader pragmatic perspective, far from being a nuisance, is an ideal application domain for distributional semantic methods.

scholarly journals MATERIALISME SEBAGAI PENGHAMBAT PEMBANGUNAN KESEJATERAAN SOSIAL

2019 ◽  
Vol 2 (1) ◽  
pp. 167-171
Author(s):  
Mohammad Sabiq ◽  
Akhmad Jayadi ◽  
Imam Nawawi ◽  
Mohammad Wasil
Keyword(s):  
Social Welfare ◽  
Cultural Values ◽  
Social Theory ◽  
Social Stress ◽  
Economic Inequality ◽  
Developed Countries ◽  
The Other ◽  
Financial Security ◽  
The One ◽  
Positive Effect

Materialism and sich are the driving spirit of the community in achieving economic and financial security that saves a holistic and socially just welfare. This can be seen from the lives of people in materialistic developed countries, where the level of social stress is higher, economic inequality widens, horizontal conflict is rife. This research uses Pierre Felix Bourdieu's social theory in seeing people trust the expenditure of material with other values, such as spiritual and cultural values ​​that are no less urgent as elements of social welfare development. This study found that materialism on the one hand has a positive effect, where people are encouraged to use material standards in measuring the level of welfare they expect. On the other hand, materialism closes the presence of values ​​such as spirituality, local wisdom and agriculture in completing more holistic welfare standards.

scholarly journals Бытие и небытие смерти в смысловой картине реально- сти и художественного текста на материале романов Леонида Леонова Дорога на Океан и Максима Горького Жизнь Клима Самгина

2018 ◽  
Vol 167 ◽  
pp. 375-383
Author(s):  
Valentyna Gerasymchuk
Keyword(s):  
Semantic Space ◽  
Literary Text ◽  
Transcendental Philosophy ◽  
The Other ◽  
Literary Texts ◽  
Human Being ◽  
Ontological Status ◽  
Physical Time ◽  
Existence And Nonexistence ◽  
The One

Existence and nonexistence of death in the semantic picture of reality and artistic text on the material of romans Leonid Leonov Road to the Ocean and Maxim Gorkogo The Life of Klim SamginIn this article the problem of death is unfolding in the semantic space of its ontological and existential conception in reality and a literary text. On the one hand, death as the concept of being is presented as its continuation, spiritual content, confirmation. On the other hand, death as a concept of non-being is considered as nothingness, rejection of being and its spiritual content.In reality the concept of death becomes an issue of the questionary and transcendental philosophy, that takes place in the physical time and metaphysical space of thought and expression. When the matter concerns the death of human being, his death acquires an ontological status of being, a status of spiritual significance. In the contrary case, it is possible to consider death and even life in terms of the concepts of being and nothingness. In literary texts the concept of death is also considered to be being or non-being, but taking into account constitutive characteristics of the text, its figurative and notional polysemant, the concept of death acquires not only aesthetic but also conceptual focus. In the article the main points of the topic of death, its being and non-being, are illustrated on the examples of specific literary texts. Буття і небуття смерті в смисловій картині реальності і художньому текстіПроблема смерті у статті розгортається в смисловому просторі онтологічного і екзистенціалістського її розуміння в реальності і в художньому тексті. З одного боку, смерть — поняття буття — постає як його продовження, його духовна наповненість, його стверждення. З другого — смерть — поняття небуття — розглядається як ніщо, як заперечення буття і його духовної наповненості.У реальності поняття смерті стає проблемою запитальної, трансцендентальної філософії, що розгортається у фізичному часі і метафізичному просторі думки і слова. І якщо йдеться про смерть буттюючої особистості, то і її смерть набуває онтологічного статусу, статусу духовної значущості, інакше можна говорити про смерть і навіть життя у поняттях небуття і ніщо. У художніх текстах поняття смерті також розглядається як буття і небуття, проте з урахуванням конститутивних особливостей тексту, його образної і смислової багатозначності, образ смерті набуває, крім онтологічної, ще й естетичну спрямованість.

scholarly journals Sustaible Ethanol Production From Sugarcane Molasses by Saccharomyce scerevisiae Immobilized on Chitosan-Coated Manganese Ferrite

2021 ◽  
Vol 5 ◽  
Author(s):  
Arianna Núñez Caraballo ◽  
Anna Iliná ◽  
Rodolfo Ramos González ◽  
Cristóbal N. Aguilar ◽  
Georgina Michelena Álvarez ◽  
...  
Keyword(s):  
Ethanol Production ◽  
Yeast Cells ◽  
Manganese Ferrite ◽  
X Ray Diffraction ◽  
Sugar Consumption ◽  
Total Consumption ◽  
Fermentation Time ◽  
Open Questions ◽  
One Step ◽  
The One

The interaction between nanostructures and yeast cells, as well as the description of the effect of nanoparticles in ethanol production are open questions in the development of this nanobiotechnological process. The objective of the present study was to evaluate the ethanol production by Saccharomyces cerevisiae in the free and immobilized state on chitosan-coated manganese ferrite, using cane molasses as a carbon source. To obtain the chitosan-coated manganese ferrite, the one-step coprecipitation method was used. The nanoparticles were characterized by X-ray diffraction obtaining the typical diffraction pattern. The crystal size was calculated by the Scherrer equation as 15.2 nm. The kinetics of sugar consumption and ethanol production were evaluated by HPLC. With the immobilized system, it was possible to obtain an ethanol concentration of 56.15 g/L, as well as the total sugar consumption at 24 h of fermentation. Productivity and yield in this case were 2.3 ± 0.2 g/(L * h) and 0.28 ± 0.03, respectively. However, at the same time in the fermentation with free yeast, 39.1 g/L were obtained. The total consumption of fermentable sugar was observed only after 42 h, reaching an ethanol titer of 50.7 ± 3.1, productivity and yield of 1.4 ± 0.3 g/(L * h) and 0.25 ± 0.4, respectively. Therefore, a reduction in fermentation time, higher ethanol titer and productivity were demonstrated in the presence of nanoparticles. The application of manganese ferrite nanoparticles shows a beneficial effect on ethanol production. Research focused on the task of defining the mechanism of their action and evaluation of the reuse of biomass immobilized on manganese ferrite in the ethanol production process should be carried out in the future.

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