Scale-Adaptive Group Optimization for Social Activity Planning

Studies have shown that each person is more inclined to enjoy a group activity when 1) she is interested in the activity, and 2) many friends with the same interest join it as well. Nevertheless, even with the interest and social tightness information available in online social networks, nowadays many social group activities still need to be coordinated manually. In this paper, therefore, we first formulate a new problem, named Participant Selection for Group Activity (PSGA), to decide the group size and select proper participants so that the sum of personal interests and social tightness of the participants in the group is maximized, while the activity cost is also carefully examined. To solve the problem, we design a new randomized algorithm, named Budget-Aware Randomized Group Selection (BARGS), to optimally allocate the computation budgets for effective selection of the group size and participants, and we prove that BARGS can acquire the solution with a guaranteed performance bound. The proposed algorithm was implemented in Facebook, and experimental results demonstrate that social groups generated by the proposed algorithm significantly outperform the baseline solutions.Comment: 20 pages. arXiv admin note: substantial text overlap with arXiv:1305.150

On Parameterized Complexity of Group Activity Selection Problems on Social Networks

In Group Activity Selection Problem (GASP), players form coalitions to participate in activities and have preferences over pairs of the form (activity, group size). Recently, Igarashi et al. have initiated the study of group activity selection problems on social networks (gGASP): a group of players can engage in the same activity if the members of the group form a connected subset of the underlying communication structure. Igarashi et al. have primarily focused on Nash stable outcomes, and showed that many associated algorithmic questions are computationally hard even for very simple networks. In this paper we study the parameterized complexity of gGASP with respect to the number of activities as well as with respect to the number of players, for several solution concepts such as Nash stability, individual stability and core stability. The first parameter we consider in the number of activities. For this parameter, we propose an FPT algorithm for Nash stability for the case where the social network is acyclic and obtain a W[1]-hardness result for cliques (i.e., for classic GASP); similar results hold for individual stability. In contrast, finding a core stable outcome is hard even if the number of activities is bounded by a small constant, both for classic GASP and when the social network is a star. Another parameter we study is the number of players. While all solution concepts we consider become polynomial-time computable when this parameter is bounded by a constant, we prove W[1]-hardness results for cliques (i.e., for classic GASP).Comment: 9 pages, long version of accepted AAMAS-17 pape

Who's who in networks. Wanted: the key group

Ballester, Calv ́o-Armengol, and Zenou (2006, Econometrica, 74/5, pp. 1403-17) show that in a network game with local payoff complementarities, together with global uniform payoff substitutability and own concavity effects, the intercentrality measure identifies the key player - a player who, once removed, leads to the optimal change in overall activity. In this paper we search for the key group in such network games, whose members are, in general, different from the players with the highest individual intercentralities. Thus the quest for a single target is generalized to a group selection problem targeting an arbitrary number of players, where the key group is identified by a group intercentrality measure. We show that the members of a key group are rather nonredundant actors, i.e., they are largely heterogenous in their patterns of ties to the third parties

An integrated fuzzy multi criteria group decision making model for handling equipment selection

The problem of handling equipment selection plays a significant role in the total cost of a mining project; so that it can affect the activity and continuity of the project and is a strategic problem. In this study, an integrated model based on two fuzzy multi-criteria decision making techniques for handling equipment selection is proposed. The proposed evaluation model is derived from group decision making, fuzzy set theory, analytical hierarchy process (AHP), and Technique to Order Preference by Similarity to Ideal Solution (TOPSIS) methods. The fuzzy AHP (FAHP) method is utilized to calculate the relative importance of the evaluation criteria, then, fuzzy TOPSIS (FTOPSIS) is applied for evaluating the feasible handling equipment in order to select the best handling system among a pool of the possible alternatives. The model is applied for a real world case study to demonstrate the capability and effectiveness of the proposed model. To investigate the result sensitiveness to the changes of the criteria weights, a sensitivity analysis is finally conducted

The virtual playground: an educational virtual reality environment for evaluating interactivity and conceptual learning

The research presented in this paper aims at investigating user interaction in immersive virtual learning environments (VLEs), focusing on the role and the effect of interactivity on conceptual learning. The goal has been to examine if the learning of young users improves through interacting in (i.e. exploring, reacting to, and acting upon) an immersive virtual environment (VE) compared to non interactive or non-immersive environments. Empirical work was carried out with more than 55 primary school students between the ages of 8 and 12, in different between-group experiments: an exploratory study, a pilot study, and a large-scale experiment. The latter was conducted in a virtual environment designed to simulate a playground. In this ‘Virtual Playground’, each participant was asked to complete a set of tasks designed to address arithmetical ‘fractions’ problems. Three different conditions, two experimental virtual reality (VR) conditions and a non-VR condition, that varied the levels of activity and interactivity, were designed to evaluate how children accomplish the various tasks. Pre-tests, post-tests, interviews, video, audio, and log files were collected for each participant, and analyzed both quantitatively and qualitatively. This paper presents a selection of case studies extracted from the qualitative analysis, which illustrate the variety of approaches taken by children in the VEs in response to visual cues and system feedback. Results suggest that the fully interactive VE aided children in problem solving but did not provide as strong evidence of conceptual change as expected; rather, it was the passive VR environment, where activity was guided by a virtual robot, that seemed to support student reflection and recall, leading to indications of conceptual change

Group Activity Selection with Few Agent Types

The Group Activity Selection Problem (GASP) models situations where a group of agents needs to be distributed to a set of activities while taking into account preferences of the agents w.r.t. individual activities and activity sizes. The problem, along with its well-known variants sGASP and gGASP, has previously been studied in the parameterized complexity setting with various parameterizations, such as number of agents, number of activities and solution size. However, the complexity of the problem parameterized by the number of types of agents, a natural parameter proposed already in the first paper that introduced GASP, has so far remained unexplored. In this paper we establish the complexity map for GASP, sGASP and gGASP when the number of types of agents is the parameter. Our positive results, consisting of one fixed-parameter algorithm and one XP algorithm, rely on a combination of novel Subset Sum machinery (which may be of general interest) and identifying certain compression steps which allow us to focus on solutions which are "acyclic". These algorithms are complemented by matching lower bounds, which among others close a gap to a recently obtained tractability result of Gupta, Roy, Saurabh and Zehavi (2017). In this direction, the techniques used to establish W[1]-hardness of sGASP are of particular interest: as an intermediate step, we use Sidon sequences to show the W[1]-hardness of a highly restricted variant of multi-dimensional Subset Sum, which may find applications in other settings as well

The effect of control strategies on sixth graders\u27 metacognitive awareness

This experimental action research study provided sixth grade students five lessons about metacognitive control skills, with pre- and post-instruction measurements of the students’ observable behaviors and notation of the students’ think-alouds regarding their metacognitive activity. The purpose of the study was twofold: 1. To test whether students’ metacognitive awareness can be increased, and 2. To compare the performance of students who initially demonstrate higher metacognitive awareness by scoring above the median on a Metacognitive Awareness Inventory with student who students scored below the median on the inventory. Because research has shown metacognitive ability to operate independently of academic ability and to enhance academic performance, studies are needed to test various methods of teaching metacognitive skills. A Metacognitive Awareness Inventory consisting of 20 items was administered, with results used to match the control and experimental groups. Each group then participated in a pre-instruction problem-solving activity while observers tallied students’ specific observable behaviors and listened to their think-alouds. Instruction during the study consisted of 5 30-minute lessons: for the control group, questioning strategies, and for the experimental group, metacognitive control skills relating to task variables, personal attitude, and organization of work area, and selection of strategies. Post-treatment measures were taken while the students participated in a computer problem-solving experiment. Results of the study showed increases in awareness of the skills for the experimental group, and although the data was not statistically significant, positive trends were apparent, especially for the students identified as low-metacognitive ability

Conceptual foundations of classes with the disciples of special medical group in secondary schools

Purpose: study and scientific rationale for new approaches to the organization of educational work with students of special medical group in secondary schools. Material : analyzed 15 scientific sources regarding the approaches of different authors to develop educational programs for students of special medical group. Results : focuses on the outstanding issues in a substantive, logistical and human aspects. Found that the selection of the content of educational material for special medical groups is an empirical question. Selection is carried out by copying the existing curriculum of physical culture for healthy children with an indication of the load reduction and exemption of complex elements. Established a complete absence of evaluation of educational achievements of pupils. Based on modern approaches to teaching students based on biomedical and didactic aspects: Leading defined function of each stage of training, fleshed main goals and objectives of the educational process, substantiated various kinds of sports activity, taking into account the diagnosis of diseases and the needs of students of different ages and gender. Conclusions : the main controversy in the decision of the designated problem. Substantiated leading features of each stage of training in special medical groups. A system of assessment of students' achievements