A nonparametric algorithm for optimal stopping based on robust optimization

Optimal stopping is a fundamental class of stochastic dynamic optimization problems with numerous applications in finance and operations management. We introduce a new approach for solving computationally-demanding stochastic optimal stopping problems with known probability distributions. The approach uses simulation to construct a robust optimization problem that approximates the stochastic optimal stopping problem to any arbitrary accuracy; we then solve the robust optimization problem to obtain near-optimal Markovian stopping rules for the stochastic optimal stopping problem. In this paper, we focus on designing algorithms for solving the robust optimization problems that approximate the stochastic optimal stopping problems. These robust optimization problems are challenging to solve because they require optimizing over the infinite-dimensional space of all Markovian stopping rules. We overcome this challenge by characterizing the structure of optimal Markovian stopping rules for the robust optimization problems. In particular, we show that optimal Markovian stopping rules for the robust optimization problems have a structure that is surprisingly simple and finite-dimensional. We leverage this structure to develop an exact reformulation of the robust optimization problem as a zero-one bilinear program over totally unimodular constraints. We show that the bilinear program can be solved in polynomial time in special cases, establish computational complexity results for general cases, and develop polynomial-time heuristics by relating the bilinear program to the maximal closure problem from graph theory. Numerical experiments demonstrate that our algorithms for solving the robust optimization problems are practical and can outperform state-of-the-art simulation-based algorithms in the context of widely-studied stochastic optimal stopping problems from high-dimensional option pricing

Improving the Security of United States Elections with Robust Optimization

For more than a century, election officials across the United States have inspected voting machines before elections using a procedure called Logic and Accuracy Testing (LAT). This procedure consists of election officials casting a test deck of ballots into each voting machine and confirming the machine produces the expected vote total for each candidate. We bring a scientific perspective to LAT by introducing the first formal approach to designing test decks with rigorous security guarantees. Specifically, our approach employs robust optimization to find test decks that are guaranteed to detect any voting machine misconfiguration that would cause votes to be swapped across candidates. Out of all the test decks with this security guarantee, our robust optimization problem yields the test deck with the minimum number of ballots, thereby minimizing implementation costs for election officials. To facilitate deployment at scale, we develop a practically efficient exact algorithm for solving our robust optimization problems based on the cutting plane method. In partnership with the Michigan Bureau of Elections, we retrospectively applied our approach to all 6928 ballot styles from Michigan's November 2022 general election; this retrospective study reveals that the test decks with rigorous security guarantees obtained by our approach require, on average, only 1.2% more ballots than current practice. Our approach has since been piloted in real-world elections by the Michigan Bureau of Elections as a low-cost way to improve election security and increase public trust in democratic institutions

Paleo-geographic reconstructions of the Ramore Head area, Northern Ireland, using geophysical and geotechnical data: paleo-landscape mapping and archaeological implications

We present early to Mid-Holocene paleo-geographic reconstructions for the Ramore Head area (Northern Ireland). This coastal area is characterized by Mesolithic occupation (c. 10–6 ka) and preserved early–Mid-Holocene peats both on- and offshore. This paper improves on previous reconstructions by employing a backstripping methodology, which removes accumulated recent deposits from identified buried paleo-landsurfaces instead of using modern topography as an analogue to the past landscape. Paleo-landsurfaces are identified offshore from seismic profiles supplemented by cores, and onshore through legacy borehole records. The paleo-landsurface can be traced offshore to depths of ?2 to ?19 m and is buried by &lt;5 m of modern sediment. It extends onshore under the coastal town of Portrush and is buried &lt;2.5–10 m below modern ground level. The identified paleo-landsurface is combined with sea-level curves from recent Glacio-Isostatic-Adjustment models to reconstruct marine transgression during the early–Mid-Holocene. Comparison is also made with reconstructions based on modern topography. Together, the identified paleo-landsurfaces and revised reconstructions can assist future site prospection on- and offshore and delimit high-potential areas for heritage management. Revised reconstructions also allow placement of extant archaeology into a more accurate context of landscape change and help develop insights into local-scale site location patterns.<br/

Universities and public libraries supporting student success: an exploratory study

As universities seek new ways to engage and support students in their learning, in Australia, students from regional and remote areas pose a challenge for universities given their geographical, social and technological isolation compared with their metropolitan counterparts. Much of the literature that address challenges associated with distance learning focus on teaching, course design and ways of accessing learning materials. Little is known about the provision of learning support services. Public libraries are well placed within their communities to assist university students with their learning needs. The aim of this research was to explore the idea of universities and public library services working together to support regional student success. The University of Southern Queensland, provided the context for this study. Semi-structured interviews with representatives from public library services in regional areas of Queensland were conducted to find out what service is currently being provided to students; challenges, opportunities and related issues. Thematic analysis was used to identify themes that told the ‘story’ within the data. Findings suggest there is an opportunity for universities and public libraries to work together to support regional student success, and that this opportunity is worthy of further discussion and exploration

Development of a complex intervention to test the effectiveness of peer support in type 2 diabetes

BACKGROUND: Diabetes is a chronic illness which requires the individual to assume responsibility for their own care with the aim of maintaining glucose and blood pressure levels as close to normal as possible. Traditionally self management training for diabetes has been delivered in a didactic setting. In recent times alternatives to the traditional delivery of diabetes care have been investigated, for example, the concept of peer support which emphasises patient rather than professional domination. The aim of this paper is to describe the development of a complex intervention of peer support in type 2 diabetes for a randomised control trial in a primary care setting. METHODS: The Medical Research Council (MRC) framework for the development and evaluation of complex interventions for randomised control trials (RCT) was used as a theoretical guide to designing the intervention. The first three phases (Preclinical Phase, Phase 1, Phase 2) of this framework were examined in depth. The Preclinical Phase included a review of the literature relating to type 2 diabetes and peer support. In Phase 1 the theoretical background and qualitative data from 4 focus groups were combined to define the main components of the intervention. The preliminary intervention was conducted in Phase 2. This was a pilot study conducted in two general practices and amongst 24 patients and 4 peer supporters. Focus groups and semi structured interviews were conducted to collect additional qualitative data to inform the development of the intervention. RESULTS: The four components of the intervention were identified from the Preclinical Phase and Phase 1. They are: 1. Peer supporters; 2. Peer supporter training; 3. Retention and support for peer supporters; 4. Peer support meetings. The preliminary intervention was implemented in the Phase 2. Findings from this phase allowed further modeling of the intervention, to produce the definitive intervention. CONCLUSION: The MRC framework was instrumental in the development of a robust intervention of peer support of type 2 diabetes in primary care. TRIAL REGISTRATION: Current Controlled Trials ISRCTN42541690

Contact-Era Chronology Building in Iroquoia:Age Estimates for Arendarhonon Sites and Implications for Identifying Champlain's Cahiagué

Radiocarbon dating is rarely used in historical or contact-era North American archaeology because of idiosyncrasies of the calibration curve that result in ambiguous calendar dates for this period. We explore the potential and requirements for radiocarbon dating and Bayesian analysis to create a time frame for early contact-era sites in northeast North America independent of the assumptions and approximations involved in temporal constructs based on trade goods and other archaeological correlates. To illustrate, we use Bayesian chronological modeling to analyze radiocarbon dates on short-lived samples and a post from four Huron-Wendat Arendarhonon sites (Benson, Sopher, Ball, and Warminster) to establish an independent chronology. We find that Warminster was likely occupied in 1615–1616, and so is the most likely candidate for the site of Cahiagué visited by Samuel de Champlain in 1615–1616, versus the other main suggested alternative, Ball, which dates earlier, as do the Sopher and Benson sites. In fact, the Benson site seems likely to date ~50 years earlier than currently thought. We present the methods employed to arrive at these new, independent age estimates and argue that absolute redating of historic-era sites is necessary to accurately assess existing interpretations based on relative dating and associated regional narratives

Ireland: Submerged Prehistoric Sites and Landscapes

Evidence of Ireland's drowned landscapes and settlements presently comprises 50 sites spread across the entire island. These comprise mainly intertidal find spots or small collections of flint artefacts. A handful of fully subtidal sites are known, generally from nearshore regions and consisting, with one exception, of isolated single finds. Evidence of organic remains is also sparse, with the exception of Mesolithic and Neolithic wooden fish traps buried in estuarine sediments under Dublin. The relatively small number of sites is probably due to lack of research as much as taphonomic issues, and thus the current evidence hints at the potential archaeological record which may be found underwater. Such evidence could contribute to knowledge of the coastal adaptations and seafaring abilities of Ireland's earliest inhabitants. Nonetheless, taphonomic considerations, specifically relating to Ireland's history of glaciation, sea-level change and also modern oceanographic conditions likely limit the preservation of submerged landscapes and their associated archaeology. Realistically, the Irish shelf is likely characterised by pockets of preservation, which makes detection and study of submerged landscapes difficult but not impossible. A range of potential routes of investigation are identifiable, including site-scale archaeological survey, landscape-scale seabed mapping, archival research and community engagement