Maximum Load Assortment Optimization: Approximation Algorithms and Adaptivity Gaps

Motivated by modern-day applications such as Attended Home Delivery and Preference-based Group Scheduling, where decision makers wish to steer a large number of customers toward choosing the exact same alternative, we introduce a novel class of assortment optimization problems, referred to as Maximum Load Assortment Optimization. In such settings, given a universe of substitutable products, we are facing a stream of customers, each choosing between either selecting a product out of an offered assortment or opting to leave without making a selection. Assuming that these decisions are governed by the Multinomial Logit choice model, we define the random load of any underlying product as the total number of customers who select it. Our objective is to offer an assortment of products to each customer so that the expected maximum load across all products is maximized. We consider both static and dynamic formulations. In the static setting, a single offer set is carried throughout the entire process of customer arrivals, whereas in the dynamic setting, the decision maker offers a personalized assortment to each customer, based on the entire information available at that time. The main contribution of this paper resides in proposing efficient algorithmic approaches for computing near-optimal static and dynamic assortment policies. In particular, we develop a polynomial-time approximation scheme (PTAS) for the static formulation. Additionally, we demonstrate that an elegant policy utilizing weight-ordered assortments yields a 1/2- approximation. Concurrently, we prove that such policies are sufficiently strong to provide a 1/4-approximation with respect to the dynamic formulation, establishing a constant-factor bound on its adaptivity gap. Finally, we design an adaptive policy whose expected maximum load is within factor 1-\eps of optimal, admitting a quasi-polynomial time implementation

Calendar.help: Designing a Workflow-Based Scheduling Agent with Humans in the Loop

Although information workers may complain about meetings, they are an essential part of their work life. Consequently, busy people spend a significant amount of time scheduling meetings. We present Calendar.help, a system that provides fast, efficient scheduling through structured workflows. Users interact with the system via email, delegating their scheduling needs to the system as if it were a human personal assistant. Common scheduling scenarios are broken down using well-defined workflows and completed as a series of microtasks that are automated when possible and executed by a human otherwise. Unusual scenarios fall back to a trained human assistant who executes them as unstructured macrotasks. We describe the iterative approach we used to develop Calendar.help, and share the lessons learned from scheduling thousands of meetings during a year of real-world deployments. Our findings provide insight into how complex information tasks can be broken down into repeatable components that can be executed efficiently to improve productivity.Comment: 10 page

Integrating Meeting and Individual Events Scheduling

Automated meeting scheduling is the task of reaching an agreement on a time slot to schedule a new meeting, taking into account the participants’ preferences over various aspects of the problem. Such a negotiation is commonly performed in a non-automated manner, that is, the users decide whether they can reschedule existing individual activities and, in some cases, already scheduled meetings in order to accommodate the new meeting request in a particular time slot, by inspecting their schedules. In this work, we take advantage of SelfPlanner, an automated system that employs greedy stochastic optimization algorithms to schedule individual activities under a rich model of preferences and constraints, and we extend that work to accommodate meetings. For each new meeting request, participants decide whether they can accommodate the meeting in a particular time slot by employing SelfPlanner’s underlying algorithms to automatically reschedule existing individual activities. Time slots are prioritized in terms of the number of users that need to reschedule existing activities. An agreement is reached as soon as all agents can schedule the meeting at a particular time slot, without anyone of them experiencing an overall utility loss, that is, taking into account also the utility gain from the meeting. This dynamic multi-agent meeting scheduling approach has been tested on a variety of test problems with very promising results

Information sharing, scheduling, and awareness in community gardening collaboration

Community gardens are places where people, as a collaborative group, grow food for themselves and for others. There is a lack of studies in HCI regarding collaboration in community gardens and considering technologies to support such collaborations. This paper reports on a detailed study of collaboration in community gardens in Greater Vancouver, Canada. The goal of our study is to uncover the unique nature of such collaborative acts. As one might expect, we found considerable differences between community gardening collaboration and workplace collaboration. The contribution is the articulation of key considerations for designing technologies for community gardening collaboration. These include design considerations like volunteerism, competences and inclusion, synchronicity, and telepresence as unique aspects of community collaboration in community garden. We also articulate the complexities of community gardening collaboration, which raise ibues like control, shared language, and collective ownership that exist more as conditions within which to design than "problems" to solve through technologies

Usability Study of Mobile Groupware Applications: A Case Study of Mobile Meeting Scheduler

Mobile groupware applications are to support users of different roles in completing tasks of mutual interests by operating mobile devices. Mobile Meeting Scheduler is an example of such applications. This software enables users of different parties to communicate with each other about the meeting time, venues, participants and subjects.  The purpose of the software is to facilitate users setting up meetings by using their mobile phones. A preliminary usability study of Mobile Meeting Scheduler suggests that evaluation of such applications is challenging.  The evaluators need insights into usability study methods for mobile groupware applications. An extensive literature survey shows that there is no directly applicable research on the subject yet. However, the analysis of Mobile Meeting Scheduler, its preliminary usability study and the relevant literature give implications on the important usability aspects of mobile groupware applications. The implications include also possible methods to conduct usability evaluations for mobile groupware applications. These implications will call for HCI researchers and practitioners to contribute further efforts to investigate practical usability study methods for mobile groupware applications. Asiasanat:groupware usability evaluation methods, mobile usability evaluation, mobile collaborative application, usability engineering, use context and user-centred desig

A conversation centric approach to understanding and supporting the coordination of social group-activities

Despite the widespread and large variety of communication tools available to us such as, text messaging, Skype, email, twitter, Facebook, instant messaging, GroupMe, WhatsApp, Snapchat, etc., many people still routinely find coordinating activities with our friends to be a very frustrating experience. Everyone, has at least once, encountered the difficulties involved with deciding what to do as a group. Some friends may be busy, others may have already seen the movie that the others want to see, and some do not like Mexican food. It is a challenge everyone has faced and continue to face. This is a result of system designers and researchers primarily focusing on understanding and supporting workplace coordination. This workplace bias has led to an assumption that the same technologies employed to facilitate workplace coordination can easily transfer to social coordination. This has created a divergence between how people actually communicate and coordinate for social reasons versus how the systems and technologies developed to support such coordination and communication are designed. As a result, researchers and designers are faced with dearth of knowledge about how to design and research systems that support people engaging in coordination and communication for more social reasons. This dissertation moves beyond previous work, both academic and commercial, which has either focused on providing structured and process oriented communication and coordination support or on the creation of yet another text chat. This research focuses on a narrower aspect of social communication and coordination, specifically, the problem of social group-activity coordination. Generally, this is the stuff people do to coordinate going out to dinner or the movies with a group of friends. This area has been under researched and as personal experience informs, poorly supported. This dissertation contains four main contributions. First, a diary study of 37 young adults aged 18 to 28 investigated the current social group-activity coordination practices resulting in an expansion of the knowledge about how social groups coordinate social group-activities and what technologies people use and why. Second, via iterative design and testing following a research through design methodology the design space for social group-activity coordination is explored over multiple design iterations. This results in the design and instantiation of a social group-activity coordination support tool improving understanding of the design requirements of tools that support social group-activity coordination. Third, a quantitative survey which confirmed many of the findings discovered during the dairy study. Fourth, the tool is evaluated in a laboratory study with 84 participants during 21 sessions. This study finds that using the conversation centric design perspective presented in this dissertation it is possible to reduce information overload and support consensus building. Also, the features provided are overwhelmingly desired with 91.4% of the participants desiring the ability and interface to make suggestions about important activity details (vs open chat) and two-thirds of the participants reporting they would prefer to use this tool over text messaging. The combination of all these different investigations into social group-activity coordination extends the knowledge about how to improve the support of social group-activity coordination and move beyond the process and systems oriented perspectives and towards conversation centric designs

An examination of coordination among friends and strangers from a coordination theory perspective

Within mobile social coordination, there is a field of study known as outeraction, the communicative processes used by people to manage future interactions. It is an important area of research because it identifies how informal interactions support complex collaboration between individuals and groups. Outeraction is primarily conducted through the interpersonal communication channels of texting, instant messaging (IM), face-to-face, and mobile phone or Skype conversations. Currently this area of research in mobile outeraction support systems is weak. It lacks a firm foundation in system building, has very few if any conceptual frameworks, and little empirical knowledge of user requirements and attitudes is known. As smartphones are becoming more common these days allowing people to conduct their outeraction on the go, the need for mobile outeraction support systems will also be on the rise. This thesis seeks to investigate how people use technology to help them coordinate social activities with friends as well as activities with strangers. From semi- structured interviews it was found that individuals use a primary and secondary means of communication when coordinating with friends. These means of communication will also shift as the agreed upon time of the activity approaches. Other findings describe how group decisions can frequently change, how individuals immerse themselves in activities with strangers, and how individuals decide on a place to do an activity. These and other findings are further described in this thesis

Preference-Based Group Scheduling

Abstract. Traditional group scheduling applications often treat users' availability as binary: free or busy. This is an unrealistic representation because not all times are equally free or busy. The inflexibility makes it difficult to find times with which everyone is truly satisfied. We present an online group scheduling approach by which users indicate four-tier preferences for meeting times on a calendar, which dynamically adjusts to provide instant feedback and suggests optimal meeting times for all participants. Our prototype is geared toward college students and the scheduling is done through a democratic and open negotiation process where everyone's preference is heard. Students who evaluated the prototype thought that the scheduling process was more efficient than the widely-used e-mail scheduling among college students, which is largely based on binary availability.