DVP Talk: Sam Ventura, 12/7 @ 4 pm in Olin 264

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Title:  Classification and Clustering for Record Linkage in Large Datasets

Abstract: Record linkage, or the process of linking records corresponding to unique entities within and/or across data sources, is an increasingly important problem in today’s data-rich world.  Due to issues like typographical errors, name variation, and repetition of common names, linking records of unique entities within and across large data sources can be a difficult task, in terms of both accuracy and computational feasibility.  We frame record linkage as a clustering problem, where the objects to be clustered are the records in the data source(s), and the clusters are the unique entities to which the records correspond.  We use the following three-step approach for record linkage:  First, records are partitioned into blocks of loosely similar records to reduce the comparison space and ensure computational feasibility.  We propose a sequential blocking approach that iterates through a nested set of decreasingly strict blocking criteria to reduce the comparison space more efficiently.  Second, we adopt an ensemble supervised learning approach to estimate the probability that a pair of records matches.  We propose a new adaptive prediction approach for classifier ensembles (specifically, random forests) that extracts and incorporates summary statistic information from the distribution of estimated probabilities.  Third, after transforming our estimated pairwise probabilities of matching to pairwise dissimilarities, we use hierarchical clustering to link matching records.  We apply these approaches to two labeled record linkage datasets:  a set of labeled inventors from the United States Patent and Trademark Office database and a compilation of lists of death records from the Syrian Civil War conflict.

Student Talk Series: Kelly Bickel, Bucknell University, Thursday, September 3rd in Olin 268 @ noon

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Title: Geometry, Meet Origami

Abstract: In this talk, we will go back in time to the ancient Greeks (or at least your high school geometry class) and take a good look at what we can draw with a compass and straight-edge. The answer is “Not Much!,” at least when compared to what a little paper folding will get us. Come prepared to trisect some angles, double some cubes, and scoff at the circle squarers.

The Bucknell Pre-calculus Requirement

College-level mathematics is exciting and empowering, and the Mathematics Department wants your experience to begin in the best way possible!  We are providing and requiring a 6-week online preparation course—the ALEKS Prep. for Calculus—for all students who will take MATH 201.  Results from previous years show that working through this online course will get you started on the path to success in college calculus.

The Prep. for Calculus course will be available starting July 19. The deadline for completion for Fall Calculus enrollment is Aug. 29; we recommend you start by Aug 1. Students with a Spring Calculus enrollment may choose to complete this requirement over the summer or over winter break.

To get started, read the Prep. for Calculus Information sheet then visit the Bucknell ALEKS Prep. for Calculus Moodle page.

Distinguished Visiting Professor Talk Series: Sergi Elizalde, Dartmouth College, November 24th @4pm in Olin 372

Title: Consecutive patterns in permutations

 

Abstract: An occurrence of a consecutive pattern sigma in a permutation pi
is a subsequence of adjacent entries of pi in the same relative
order as the entries of sigma. For example, occurrences of the
consecutive pattern 21 are descents, and alternating permutations
are those that avoid the consecutive patterns 123 and 321. The
systematic study of consecutive patterns in permutations started over
a decade ago.  More recently, consecutive patterns have become
relevant in the study of one-dimensional dynamical systems, and they
are useful in creating tests to distinguish random from deterministic
time series.

We show that the number of permutations avoiding the consecutive
pattern 12…m —that is, containing no m adjacent entries in
increasing order— is asymptotically larger than the number of
permutations avoiding any other consecutive pattern of length m. At
the other end of the spectrum, the number of permutations avoiding
12… (m-2)m(m-1) is asymptotically smaller than for any other
consecutive pattern.

Problem of the Week Instructions and This Week’s Problem

Try the Math Department Problem of the Week!

New Problems every Tuesday at 1pm!

How it Works:

  1. Pick up a problem sheet in the Math Department on the third floor of Olin Science
  2. Do the problem!
  3. Turn in your solution in the Math Dept. Office in Olin 380 before 5pm the following Monday.
  4. Every correct solution over the course of the semester gives you a chance to win a $50 Amazon Gift Card.
  5. Keep doing the Problem of the Week! Each correct solution adds your name to the drawing at the end of the semester!

2 correct solutions = 2 tickets in the drawing!

 

Problem of the Week #4:

 

POTW 4

Distinguished Visiting Professor Talk Series: Eva A. Gallardo Gutierrez, Universidad Complutense de Madrid, October 23rd @ 4pm in Olin 372

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Title: Rota’s Universal Operators

Abstract: The Invariant Subspace Problem for Hilbert spaces is a long-standing question and the use of universal operators in the sense of Rota has been one tool for studying the problem. The best known universal operators have been adjoints of analytic Toeplitz operators or unitarily equivalent to them. We present many examples of Toeplitz operators whose adjoints are universal operators and exhibit some of their common properties. Some ways in which the invariant subspaces of these universal operators interact with operators in their commutants are given. Special attention is given to the closed subalgebra, not always the zero algebra, of compact operators in their commutants.