I formerly taught a computer science course each term here at UMass Boston. My day job was as a software engineer at various companies, most recently at Ab Initio. I am now fully retired; I retired from teaching at UMass Boston in 2022 and from my full-time job in July, 2024. email: offner "at" cs.umb.edu This is the best address to use when sending me email, because email here also gets forwarded to me at home.

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(Some of) what I was doing for a living as a software engineer:

• TStreams Project Papers
  Here are papers and technical reports from the TStreams project, which I worked on with Kath Knobe and Alex Nelson at the Hewlett-Packard Cambridge Research Lab.
• High Performance Fortran (HPF) Papers
  Here are papers and technical reports from the HPF compiler project at Digital and Compaq.

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Here are some expository papers I am putting up for public enjoyment:

1. These papers are written at the level of an advanced undergraduate—say, someone who has been through advanced calculus and linear algebra.
   • Repetitions of Words and the Thue-Morse Sequence
   • Finite Fields and Pseudo-Random Number Generation
   • Some Early Analytic Number Theory
   • Computing the Digits in π
2. This paper is written at the level of a first-year graduate student. As I was writing this up, I got interested in some historical questions. At the end of the paper I include a historical sketch that includes my views on two controversial topics:
   • Did Abel prove "Abel's theorem" on the convergence of power series? (Yes, he did.)
   • Did Dirichlet really come up with the modern definition of function? (I think it's quite reasonable to say that he did.)
   and also my thoughts on a question that I have not seen dealt with seriously before:
   • Why was Fejér's theorem such a sensation, since the essential results had been known for many years?
   • A Little Harmonic Analysis
3. This is actually what I was using as my "last lecture" in CS 450 for the last few years I taught it. It's an account of the origins of the lambda calculus, from which the language Scheme developed; as well as the significance of this in the development of computer science generally. I'm not really an expert on this, but this is at any rate my own understanding of how it all happened.
   • Alonzo Church, Lambda Calculus, and the Birth of Theoretical Computer Science
4. This paper is standard computer science. Much of it is not readily available in books, however. It's only the bare beginning; I'd like to add a lot more to this:
   • Notes on Graph Algorithms Used in Optimizing Compilers

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I recently finally got around to writing up a polished report of a smooth and best-possible version of the "Master Theorem" for divide-and-conquer recurrences. Here it is:

• A Best Possible General Form of the "Master Theorem" for Divide-and-Conquer Recurrences

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And here are my thoughts on some issues in secondary school science and mathematics education. The paper looks at—and gives reasons for rejecting—three principles that have been widely promoted in recent educational reform debates. These principles were in particular popularized around 1980-2000 by Theodore Sizer and his Coalition of Essential Schools, but in fact, they are really older than that, and never seem to die out:

• "Less is more."
• Exhibitions as a goal or proof of successful education. Sometimes the phrase "authentic assessment" is used for this principle.
• High school teachers as generalists or coaches rather than subject-matter specialists. Sometimes this is referred to as an "interdisciplinary" model of education.

In considering these principles, the paper touches on some common misconceptions of science and the "scientific method". In an extended discussion, it contrasts these with a description of what science is, what scientists do, and—based on this—what are reasonable objectives for secondary school science and mathematics education.

• Dumbing Down Mathematics and Science: Sizer's Essential Schools Proposal