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Title: From cows to inductive types; or What are numbers?
Date and Time:  Wednesday 5 September; 1:10 pm
Location: Room 218, Ingkarni Wardli
Speaker: Dr David Roberts
Abstract:We all use numbers every day, but have you stopped to think how numbers are defined? About what they are? What they should and cannot be? This talk will span several thousand years of the history of numbers, from ancient Mesopotamian accounting to contemporary structuralism.

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Upcoming Colloquiums

Title: Topological Data Analysis
15:10 Fri 31 August, 2018 :: Napier 208 :: Dr Vanessa Robins :: Australian National University
Abstract:
Topological Data Analysis has grown out of work focussed on deriving qualitative and yet quantifiable information about the shape of data. The underlying assumption is that knowledge of shape – the way the data are distributed – permits high-level reasoning and modelling of the processes that created this data. The 0-th order aspect of shape is the number pieces: “connected components” to a topologist; “clustering” to a statistician. Higher-order topological aspects of shape are holes, quantified as “non-bounding cycles” in homology theory.  These signal the existence of some type of constraint on the data-generating process.
Homology lends itself naturally to computer implementation, but its naive application is not robust to noise. This inspired the development of persistent homology: an algebraic topological tool that measures changes in the topology of a growing sequence of spaces (a filtration). Persistent homology provides invariants called the barcodes or persistence diagrams that are sets of intervals recording the birth and death parameter values of each homology class in the filtration.  It captures information about the shape of data over a range of length scales, and enables the identification of “noisy” topological structure.
Statistical analysis of persistent homology has been challenging because the raw information (the persistence diagrams) are provided as sets of intervals rather than functions. Various approaches to converting persistence diagrams to functional forms have been developed recently, and have found application to data ranging from the distribution of galaxies, to porous materials, and cancer detection.

Title: Mathematical modelling of the emergence and spread of antimalarial drug resistance
15:10 Fri 14 Sep, 2018 :: Napier 208 :: Dr Jennifer Flegg :: University of Melbourne
Abstract:
Malaria parasites have repeatedly evolved resistance to antimalarial drugs, thwarting efforts to eliminate the disease and contributing to an increase in mortality. In this talk, I will introduce several statistical and mathematical models for monitoring the emergence and spread of antimalarial drug resistance. For example, results will be presented from Bayesian geostatistical models that have quantified the space-time trends in drug resistance in Africa and Southeast Asia. I will discuss how the results of these models have been used to update public health policy.

Title: TBA
15:10 Fri 5 October, 2018 :: Napier 208 :: A/Prof Scott Morrison :: Australian National University

Title: TBA
15:10 Fri 12 October, 2018 :: Napier 208 :: A/Prof Kais Hamza :: Monash University

Title: TBA
15:10 Fri 26 October, 2018 :: Napier 208 :: A/Prof Chris Drovandi :: Queensland University of Technology

 

Recent Colloquiums

Title: Tales of Multiple Regression: Informative missingness, Recommender Systems, and R2-D2
15:10 Fri 17 August, 2018: Napier 208: Prof Howard Bondell: University of Melbourne
Abstract:
In this talk, we briefly discuss two projects tangentially related under the umbrella of high-dimensional regression. The first part of the talk investigates informative missingness in the framework of recommender systems. In this setting, we envision a potential rating for every object-user pair. The goal of a recommender system is to predict the unobserved ratings in order to recommend an object that the user is likely to rate highly. A typically overlooked piece is that the combinations are not missing at random. For example, in movie ratings, a relationship between the user ratings and their viewing history is expected, as human nature dictates the user would seek out movies that they anticipate enjoying. We model this informative missingness, and place the recommender system in a shared-variable regression framework which can aid in prediction quality. The second part of the talk deals with a new class of prior distributions for shrinkage regularization in sparse linear regression, particularly the high dimensional case. Instead of placing a prior on the coefficients themselves, we place a prior on the regression R-squared. This is then distributed to the coefficients by decomposing it via a Dirichlet Distribution. We call the new prior R2-D2 in light of its R-Squared Dirichlet Decomposition. Compared to existing shrinkage priors, we show that the R2-D2 prior can simultaneously achieve both high prior concentration at zero, as well as heavier tails. These two properties combine to provide a higher degree of shrinkage on the irrelevant coefficients, along with less bias in estimation of the larger signals.

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Congratulations to Michael Hallam for winning the Elsevier Young Scientist Award in 2018! The award was presented at the workshop entitled, Index theory and applications to positive scalar curvature and related areas, funded by the Institute for Geometry and its Applications (Adelaide) and AMSI (Melbourne), held at University of Adelaide, June 4-8, 2018.

Michael Hallam is currently finishing his MPhil at the University of Adelaide under the supervision of Elder Professor Mathai Varghese and Dr David Baraglia. His research focuses on K-theoretic and analytic methods on noncompact manifolds. The title of his prize-winning talk was “EndPeriodic K-Homology and Spin Bordism” based on the joint paper. Michael Hallam was also the 2017 Bernard Neumann Prize winner for the best student talk at the Australian Mathematical Society’s annual meeting in Sydney in December 2017. He was admitted with full PhD scholarship at University of Oxford, commencing in September 2018.

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The MPhil student, Michael Hallam (supervisors Varghese and Baraglia), won the 2018 Elsevier Young Scientist Award for the best student talk at the IGA/AMSI workshop entitled,  Index theory and applications to positive scalar curvature and related areas,  held June 4-8, 2018. He also receives a cash award of USD 750. Congratulations to Michael!

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Congratulations to MPhil student in Pure Mathematics, John McCarthy (Supervisors Varghese, Baraglia) who has been admitted with full scholarship to the PhD program at Imperial College (London) to work with Richard Thomas! Congratulations to PhD student in Pure Mathematics, Hao Guo (Supervisors Varghese, Hang Wang) who has been offered an NSF funded postdoc at Texas […]

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Title: A Hecke module structure on the KK-theory of arithmetic groups When: Friday, 2 March 2018 at 1:10pm in Barr Smith South Polygon Lec theatre  Speaker: Bram Mesland (Unversität Bonn) Abstract: Let $G$ be a locally compact group, $\Gamma$ a discrete subgroup and $C_{G}(\Gamma)$ the commensurator of $\Gamma$ in $G$. The cohomology of $\Gamma$ is a […]

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Congratulations to our AMSI Vacation Research Scholars, Tobin South and Michael Ucci who received both of the prizes for the best presentation at the recent #AMSIConnect2018 conference. It is an outstanding achievement for our students that have won all of the available prizes against a field of students from across the country!

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Congratulations to Mr Michael Hallam (supervisors Varghese and Baraglia) on being awarded the prestigious 2017 B H Neuman prize for the most outstanding student talk presented at the Annual Meeting of the Australian Mathematical Society. He has also been admitted with a full PhD scholarship to the University of Oxford. More information: http://www.austms.org.au/The+Bernhard+Neumann+Prize”

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Title: Calculating optimal limits for transacting credit card customers 15:10 Fri 2 Mar, 2018 :: Horace Lamb 1022 :: Prof Peter Taylor :: University of Melbourne Abstract: Credit card users can roughly be divided into `transactors’, who pay off their balance each month, and `revolvers’, who maintain an outstanding balance, on which they pay substantial interest. In […]

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Congratulations to Professor of Mathematical Sciences, Yvonne Stokes, on being awarded the 2018 EO Tuck Medal for outstanding research and distinguished service to the field of Applied Mathematics. She is pictured with Professor Peter Taylor from the University of Melbourne. More information: http://www.anziam.org.au/The+EO+Tuck+Medal Photo: Mark McGuinness

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