Kurtis Heimerl

Greedy bidding strategies for keyword auctions

How should players bid in keyword auctions such as those used by Google, Yahoo! and MSN?allWe consider greedy bidding strategies for a repeated auction on a single keyword, where in each round, each player chooses some optimal bid for the next round, assuming that the other players merely repeat their previous bid. We study the revenue, convergence and robustness properties of such strategies. Most interesting among these is a strategy we call the balanced bidding strategy (BB): it is known that BB has a unique fixed point with payments identical to those of the VCG mechanism. We show that if all players use the BB strategy and update each round, BB converges when the number of slots is at most 2, but does not always converge for 3 or more slots. On the other hand, we present a simple variant which is guaranteed to converge to the same fixed point for any number of slots. In a model in which only one randomly chosen player updates each round according to the BB strategy, we prove that convergence occurs with probability 1.We complement our theoretical results with empirical studies.

CommunitySourcing: engaging local crowds to perform expert work via physical kiosks

Online labor markets, such as Amazons Mechanical Turk, have been used to crowdsource simple, short tasks like image labeling and transcription. However, expert knowledge is often lacking in such markets, making it impossible to complete certain classes of tasks. In this work we introduce an alternative mechanism for crowdsourcing tasks that require specialized knowledge or skill: communitysourcing --- the use of physical kiosks to elicit work from specific populations. We investigate the potential of communitysourcing by designing, implementing and evaluating Umati: the communitysourcing vending machine. Umati allows users to earn credits by performing tasks using a touchscreen attached to the machine. Physical rewards (in this case, snacks) are dispensed through traditional vending mechanics. We evaluated whether communitysourcing can accomplish expert work by using Umati to grade Computer Science exams. We placed Umati in a university Computer Science building, targeting students with grading tasks for snacks. Over one week, 328 unique users (302 of whom were students) completed 7771 tasks (7240 by students). 80% of users had never participated in a crowdsourcing market before. We found that Umati was able to grade exams with 2% higher accuracy (at the same price) or at 33% lower cost (at equivalent accuracy) than traditional single-expert grading. Mechanical Turk workers had no success grading the same exams. These results indicate that communitysourcing can successfully elicit high-quality expert work from specific communities.

The village base station

Cellular communications, including handsets and base stations, have become ubiquitous technologies throughout the developing and developed world. Roughly three billion users spend large portions of their income on these basic communications [1]. However, the remaining half of the world currently has limited access, in large part due to lack of network coverage. Some areas do not have a high enough population density to support a traditional cellular deployment. Other areas are too far from established infrastructure to make a deployment economically feasible. This leads to many rural areas where there is no network coverage at all.

GSM whitespaces: An opportunity for rural cellular service

The GSM network is the largest network on Earth, providing vital communications service to billions of people. Yet hundreds of millions of people live outside the coverage of existing cellular providers. Recently, researchers have demonstrated a new model of cellular connectivity, community cellular, that has the potential to bring coverage to extremely rural populations. Although the total capital costs for these networks (<;US

Analysis of smartphone adoption and usage in a rural community cellular network

10,000) are affordable for rural communities, the high financial and political cost of access to spectrum in GSM bands makes running a legal community cellular network nearly impossible. This is despite the fact that very rural areas typically have substantial amounts of licensed GSM spectrum that is not actively used. We define this unused spectrum as GSM whitespace. Like TV whitespaces, we argue that GSM whitespaces should be regulated for dynamic spectrum sharing, and that doing so will support the growth of community cellular networks and thereby improve rural access to communications services. We propose a hybrid sensing and database-driven spectrum sharing scheme called Nomadic GSM that provides safe coexistence between primary and secondary users without requiring coordination or cooperation from existing license holders. Nomadic GSM also mitigates concerns about “spectrum squatting” by secondaries and provides regulators visibility into and control of the spectrum usage of secondary operators. Lastly, we implement and evaluate a prototype Nomadic GSM system that is fully compatible with existing, unmodified GSM handsets and has been deployed in a real-world community cellular network in Papua, Indonesia.

Metamouse: multiple mice for legacy applications

The smartphone has been touted as the technology of the 21st century. Global smartphone adoption rates are growing rapidly, up to over 24% in 2014, with usage increasing 25% in the last year. However, rural areas are often the last places to benefit from these technological trends. Utilizing cellular network registration logs, we explore the adoption and usage of smartphones in an extremely remote community in Indonesia. We found that 16% of the phones in the area were smartphones (compared to between 14--24% in Indonesia). This shows that smartphone adoption in rural Indonesia is similar to the rest of the country. We also explored usage in the network, and found that smartphone users were more likely to text, especially to other smartphone users.

Convergence of Position Auctions under Myopic Best-Response Dynamics

Single Display Groupware (SDG) solutions have been used to create software for disadvantaged children, particularly in the developing world. SDG allows for greater utilization of the limited infrastructure available to these kids. However, SDG faces challenges in working with legacy applications. Our technology, called metamouse, takes a step toward an integrated multi-user application by allowing users to collaborate within unmodified legacy educational software. We conducted a preliminary qualitative user study of our technology with educational software in schools around Bangalore, India. We found that Metamouse is easily learned, encourages collaborative discussion among students, and allows for the use of existing educational applications with no modification.

An Investigation of Phone Upgrades in Remote Community Cellular Networks

We study the dynamics of multiround position auctions, considering both the case of exogenous click-through rates and the case in which click-through rates are determined by an endogenous consumer search process. In both contexts, we demonstrate that dynamic position auctions converge to their associated static, envy-free equilibria. Furthermore, convergence is efficient, and the entry of low-quality advertisers does not slow convergence. Because our approach predominantly relies on assumptions common in the sponsored search literature, our results suggest that dynamic position auctions converge more generally.

HCI Across Borders: Paving New Pathways

In the last decade, billions of people worldwide have upgraded from basic 2G feature phones to data-enabled 4G smartphones. In most cases, people upgrade in areas with 4G coverage (typically cities and large towns), but increasingly, people choose to upgrade in areas that only have 2G coverage or no cellular coverage at all. This counterintuitive behavior -- upgrading your phone despite living in an area that does not actively support many of the features of that new device -- is the focus of this work. We investigate the rates and reasons for 4G upgrades and adoption in two extremely remote areas in Indonesia and the Philippines. Our mixed-methods approach combines the quantitative analysis of several years of mobile phone registration logs with the qualitative analysis of multiple interviews in one of these communities. We learn that users are rapidly switching from 2G to 4G technology and skipping 3G entirely; the data suggest that these villages will soon have sufficient 4G phone adoption to justify the investment required to upgrade base stations to 4G technology. The interviews suggest people are making these switches primarily to support consumption of media such as games, videos, and music. Similarly, users switch devices because of damage, often leading to downgrades to more resilient feature phones. We also find that, despite the general value seen in more modern 4G phones, 2G phones are more shared and more active on the network.

Crowdsourcing Rural Network Maintenance and Repair via Network Messaging

The HCI Across Borders (HCIxB) community has been growing in recent years, thanks in particular to the Development Consortium at CHI 2016 and the HCIxB Symposium at CHI 2017. For CHI 2018, we plan to organize an HCIxB symposium that focuses on building the scholarship potential and quality of junior HCIxB researchers - paving new pathways, while also strengthening the ties between the more and less junior members of the community.