Operational Research and Statistics Seminars 2014-2015
All seminars will commence at 12:10pm in room M/0.34, The Mathematics Building, Cardiff University, Senghennydd Road (unless otherwise stated).
1 October 2014
Speaker: Dr Trivikram Dokka (Lancaster)
Title: New polyhedral results for the three-index assignment problem.
Abstract: PDF Download
20 October 2014 at 17:30 in Room M/0.40
Speaker: Prof. Michael Carter (Toronto).
Title: Health System Patient Flow Simulation Model.
Abstract: Our cross-sector patient flow model is a system dynamics simulation focused on the flow rates of patients between health system sectors, and the feedback structures around them. It takes a whole-system, strategic perspective, and is designed to produce output that captures the direction and magnitude resulting from policy changes around patient pathways and service levels.
The model was developed within a geographically large health region of around one million people. It was constructed based on consultations with four expert panels: health policy leaders, acute, institutional and home and community care. The first panel identified the policy levers targeting flows of patients between healthcare sectors, while the other three panels were engaged to develop causal loop diagrams (CSD) that explained admission and discharge flows of their respective sectors. Qualitative input from these panels was merged with health system data to develop a stock-and-flow structure of the health region. Patients are grouped into cohorts by age, sex, clinical condition, referral source and discharge destination. The model output was validated against admission and discharge data collected over a four year period.
The model has been applied to both qualitative (CSD) and quantitative (stock and flow) decision problems. The CSD model was used by the Ontario Ministry of Health and Long Term Care to test a new slow stream rehab option for complex patients. The model demonstrated several negative unintended consequences and led the policy team to revise their recommendations. The quantitative model has been used to validate the Ontario Stroke Strategy to estimate length of stay improvements. We are currently working with the Ministry to make the tool more widely accessible.
5 November 2014
Speaker: Dr Ben Torsney (Glasgow),.
Title: Optimal Design, Lagrangian and Linear Model Theories: Further Developments on a Fusion.
20 November 2014
Speaker: Dr Vadim Lozin (Warwick).
Please note change of room for this - M/2.01.
Title: Combinatorics and algorithms for augmenting graphs.
Abstract: The notion of augmenting graphs generalizes the Berge's idea of augmenting chains that has been used by Edmonds in his celebrated solution of the maximum matching problem. This problem is a special case of the more general problem of finding a maximum independent set in a graph. Recently, the augmenting graph approach has been successfully applied to solve the maximum independent set problem in various other special cases. However, our knowledge of augmenting graphs is still very limited, and we do not even know what the minimal *infinite* classes of augmenting graphs are. In this talk, we give an answer to this question and apply it to extend the area of polynomial-time solvability of the maximum independent set problem.
18 February 2015
Speaker: Christian Henning (UCL).