http://jamesrwilcox.com/ James Wilcox's Blog. https://jamesrwilcox.com/teaching-principles.html https://jamesrwilcox.com/teaching-principles.html Fri, 29 Apr 2022 00:00:00 -0700 This living document collects James's Teaching Principles(tm). http://homes.cs.washington.edu/~jrw12/InductionExercises.html http://homes.cs.washington.edu/~jrw12/InductionExercises.html Tue, 21 Feb 2017 00:00:00 -0700 This post collects several Coq exercises on generalizing the induction hypothesis. http://homes.cs.washington.edu/~jrw12/Peterson.dfy.html http://homes.cs.washington.edu/~jrw12/Peterson.dfy.html Tue, 10 Jan 2017 00:00:00 -0700 This code-only post is a port of the proof of Peterson's Algorithm to Dafny. It also serves as a good example of how to reason about concurrent systems in Dafny, essentially by writing a thread scheduler. http://homes.cs.washington.edu/~jrw12/Counter.html http://homes.cs.washington.edu/~jrw12/Counter.html Sun, 24 Apr 2016 00:00:00 -0700 In this long-awaited post, we'll show how to implement and verify a simple distributed system using network semantics. http://homes.cs.washington.edu/~jrw12/SharedMem.html http://homes.cs.washington.edu/~jrw12/SharedMem.html Fri, 8 May 2015 00:00:00 -0700 In this post, we take a break from distributed systems to look at shared memory systems. As a case study, we give a proof that Peterson's algorithm provides mutual exclusion. http://homes.cs.washington.edu/~jrw12/network-semantics.html http://homes.cs.washington.edu/~jrw12/network-semantics.html Thu, 16 Apr 2015 00:00:00 -0700 This is the first post in a series on Verdi. In this post, we'll get our feet wet by defining a formal model of how distributed systems execute on the network. http://homes.cs.washington.edu/~jrw12/more-cardinality.html http://homes.cs.washington.edu/~jrw12/more-cardinality.html Mon, 20 Oct 2014 00:00:00 -0700 In this short, code-heavy post, we extend some of the work from a previous post to reason about the cardinalities of sums and products. http://homes.cs.washington.edu/~jrw12/dep-destruct.html http://homes.cs.washington.edu/~jrw12/dep-destruct.html Sun, 14 Sep 2014 00:00:00 -0700 This post shows how to get around the limitations of the destruct tactic when doing case analysis on dependent types, without resorting to the dependent destruction tactic, which relies on additional axioms. http://homes.cs.washington.edu/~jrw12/runtime.html http://homes.cs.washington.edu/~jrw12/runtime.html Thu, 04 Sep 2014 00:00:00 -0700 This brief post records Mike's description of the three ways of combining the words "run" and "time" in computer science writing. http://homes.cs.washington.edu/~jrw12/mstd2.html http://homes.cs.washington.edu/~jrw12/mstd2.html Thu, 12 Jun 2014 00:00:00 -0700 This is the (much delayed) second post in a series on More Sums than Difference Sets. In this post, we'll take a first crack at the question, "How many MSTD sets are there?" To do so, we'll write a straightforward C program that counts MSTD sets. Then we'll run it to count MSTD sets and benchmark its performance. http://homes.cs.washington.edu/~jrw12/tail-mod-cons.html http://homes.cs.washington.edu/~jrw12/tail-mod-cons.html Thu, 10 Apr 2014 00:00:00 -0700 Tail recursion has come up in a few conversations this week. This post explores a generalization of tail call optimization that I wasn't aware of until Doug described it to me. http://homes.cs.washington.edu/~jrw12/mstd1.html http://homes.cs.washington.edu/~jrw12/mstd1.html Mon, 03 Mar 2014 00:00:00 -0800 This is the first post in a series on "More Sums than Differences" Sets. In this post, we'll get our terminology straight and ask a lot of questions. http://homes.cs.washington.edu/~jrw12/proxy-js.html http://homes.cs.washington.edu/~jrw12/proxy-js.html Tue, 31 Dec 2013 00:00:00 -0800 I use the UW proxy to access the ACM digital library from off campus, but it's annoying to type the proxy URL every time I click a link to a new paper. Here are two ways to make life easier.