Author Archives: Swarat Chaudhuri

by | April 30, 2015 · 10:12 am

Ranking CS Departments by Publication Productivity, Interactively

Anyone familiar with American academia will tell you that the US News rankings of academic programs play an outsized role in this world. Among other things, US News ranks graduate programs of computer science, by their strength in the field at large as well as certain specialties. One of these specialties is Programming Languages, the focus of this blog.

The US News rankings are based solely on surveys. Department heads and directors of graduate studies at a couple of hundred universities are asked to assign numerical scores to graduate programs. Departments are ranked by the average score that they receive.

It’s easy to see that much can go wrong with such a methodology. A reputation-based ranking system is an election, and elections are meaningful only when their voters are well-informed. The worry here is that respondents are not necessarily qualified to rank programs in research areas that are not their own. Also, it is plausible that respondents would give higher scores to departments that have high overall prestige or that they are personally familiar with.

In this post, I propose using publication metrics as an input to a well-informed ranking process. Rather than propose a one-size-fits-all ranking, I provide a web application to allow users to compute their own rankings. This approach has limitations, which I discuss in detail, but I believe it’s a reasonable start to a better system.

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Filed under Process, Rankings, Research, Science

by | March 16, 2015 · 9:20 am

Teaching and Researching Programming Languages at a Liberal Arts College

During my tenure as a student and professor, I have been to many talks offering career advice to graduate students. Most of these talks focus on careers in research universities and industrial research labs, and leave out discussion of institutions, such as liberal arts colleges, that are primarily concerned with undergraduate education. This is unfortunate because many liberal arts colleges are highly selective institutions that offer exciting careers that mix research and teaching, albeit in a different way than careers in research universities.

One way to reduce the information deficit about liberal arts colleges is to report on the experiences of those who work at one. This is what we do in the present post. Specifically, I interview Steve Freund, who is a professor of computer science at Williams College, ranked by US News as the top liberal arts college in America. Steve is a highly successful PL researcher, known for his significant contributions to the analysis of concurrent programs. As a result, he is in a great position to give PL Enthusiast readers a view into what it’s like to be a teacher and researcher at a liberal arts institution. Continue reading →

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by | January 1, 2015 · 10:53 am

SNAPL: A new kind of PL conference

The Summit on Advances in Programming Languages (SNAPL) is a new kind of PL conference, focused on big-picture questions rather than concrete technical results. The conference will be held for the first time in Asilomar, CA, from May 3 to 6, 2015.

The submission deadline is January 9, 2015 — if you have a long-term vision about where the field of PL should go, you ought to submit a paper.

Here we post an interview with Shriram Krishnamurthi, who is a professor at Brown University and one of the organizers of the conference.[ref]My co-blogger, Mike Hicks, is on the SNAPL program committee.[/ref]

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by | December 2, 2014 · 9:09 am

Collaboration in PLDI and OOPSLA

A few weeks ago, I posted about an analysis of collaboration in the POPL community. In that post, I promised similar analyses for a few other conference-defined communities as well. Well, here they are. In this post, I will report on an analysis of community structure in two other premier SIGPLAN conferences: PLDI and OOPSLA.

Methodology

The methodology for the analysis was similar to that in my earlier post on POPL. The questions I asked were:

  • Who works with whom in the community defined by a conference X?
  • Are there prominent clusters of researchers who frequently publish papers with each other?
  • Which papers/researchers are at the center of the community (that is, who are the Kevin Bacons of community X)?

To answer these questions, I used data from the DBLP database to construct, for each conference, an overlap graph: a graph where nodes represent papers with more than 1 author published in the period 2005-2014, and edges connect pairs of papers that have at least one author in common. For each graph, I generated the set of connected components (which correspond to disjoint subcommunities) and ran some further analyses on the largest component. Continue reading →

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by | October 21, 2014 · 8:52 am

Is POPL really one research community?

I was recently in Princeton for the program committee meeting of the POPL conference. It was a lot of fun. David Walker, the program chair, offered excellent leadership, and I am excited about the program that we ended up selecting. I look forward to seeing many of you at the conference (Mumbai, January 2015).

POPL is a broad conference, and you really feel this when you attend its PC meeting. You inevitably discuss papers with fellow PC members whose backgrounds are very different from your own. Of the papers discussed, there are many that use techniques about which you only have rudimentary knowledge.

One thing I kept wondering at the meeting was: is POPL really one research community? Or is it really a union of disjoint sets of researchers who work on different themes within POPL, for example types or denotational semantics or abstract interpretation? Perhaps researchers in these sub-communities don’t really work with each other, even if they share a vision of reliable software and productive programming.

The question was bugging me enough that I decided to try to answer it through an analysis of actual data. The results I found were intriguing. The takeaway seems to be that POPL is indeed one family, but not a particularly close one. Continue reading →

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by | September 25, 2014 · 8:04 am

Bridging Algorithms and Programming Languages

In the computing stack, PL sits between algorithms and systems. Without algorithms to implement or computer systems to run them on, there would be no need for programming languages. However, the research communities that study algorithms, PL, and systems don’t really have much of an overlap. This is perhaps unavoidable: computer science is now a mature field, and researchers in mature fields tend to pursue specialized and technical research questions.

At the same time, it seems important that the approaches — assumptions and methods — of different subfields of computing be compatible to some extent. At the end of the day, computer science aims to produce solutions for the whole computing stack. An “impedence mismatch” between its subfields compromises our ability to come up with such end-to-end solutions.

This suggests that the comparative study of assumptions, techniques and cultures of different CS fields (a sort of “comp lit” for computer science) is potentially valuable.

Personally, I have always been intrigued by the relationship between the fields of programming languages and algorithms. In this post, I discuss similarities and differences between these two areas, and argue that their synthesis could be interesting for both research and teaching.

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Filed under Algorithms, Education, Research directions

by | September 2, 2014 · 8:40 am

Who teaches functional programming?

A couple of months ago, we posted about the research program of SocioPLT, whose goal is to study why some languages get adopted more than others. As part of a study, the investigators ranked languages according to their frequency of use in Sourceforge projects during the period 2000-2010. An interesting finding was that among the top 20 languages in these rankings, there wasn’t even one functional language.

Academic PL researchers tend to love functional programming, so many of us would find this fact depressing. However, it seems that we academics are at least partly to blame for this state of affairs. For functional programming to be embraced in the “real world”, universities must teach it. In this post, I show that few universities do. In particular, functional programming is a significant part of the core programming sequence at only 9 of the top 33 American schools, and is not offered at all in about 40% of these schools.  Continue reading →

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Filed under Education, Language adoption

by | August 25, 2014 · 1:44 pm

Spotlight: Bill Harris

This post continues our series on up-and-coming PL researchers who are about to embark on independent research careers. This week, we feature Bill Harris, who will start as an assistant professor at Georgia Tech in Fall 2014. Continue reading →

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by | August 11, 2014 · 1:29 pm

Spotlight: Cindy Rubio Gonzalez

In this post, we continue our ongoing series on PL researchers who are about to start independent research positions. This week, we feature Cindy Rubio Gonzalez, who is starting as an assistant professor at the University of California, Davis in the Fall.

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by | July 28, 2014 · 3:32 pm

Program verification in the undergraduate CS curriculum (Part II)

[This is the second part of a two-post series. The first part is here.]

Recently, I talked about using program verifiers in teaching proof techniques in undergraduate CS, and my own experience with using the Dafny verifier in an algorithms class. One thing that that post was missing was a student perspective. So I asked three of my students — Julie Eisenberg, Rebecca Smith, and Matthew Dunn-Rankin — what they thought of Dafny. In this post, I summarize their insightful feedback and ponder about its implications.

The takeaway message for me is that verification tools such as Dafny are an excellent way of introducing students to formal proofs. At the same time, some care is needed as we integrate these tools with our pedagogy. In particular, the automated reasoning capabilities of Dafny aren’t an unadulterated blessing, and we must make sure that students understand how to do formal proofs fully manually. We ought to also invest more effort on tools that make the proof process more productive, for example by giving users more feedback on why an attempt at a formal proof failed.  Continue reading →

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Filed under Education, Formal verification, MOOCs