Wadler's Blog

Surface detail from subBlue on Vimeo.

Video of a 3D fractal by subBlue. Anyone know which fractal this is or how it is generated? Thanks to Mike Fourman.

An open letter to my colleagues in the School of Informatics.

Colleagues,

Here are four people to think of when considering whether to join the
UCU strike to preserve our pensions on Thursday 24 March.

Yourself. The changes to pensions are estimated to remove £150K in
value over the lifetime of your pension (presuming the two-tier scheme
stays in place, see below). The most significant changes don't take
effect immediately, but bite over time:

• Capping cover for inflation. Full cover to 5%, half cover to 15%;
  that is, a 10% increase when inflation is 15% or higher. Recall
  inflation averaged 16% per year between 1974 and 1980: a cut of 6%
  over six years compounds to a 31% reduction, lasting over the
  remaining lifetime of the pension.
  
  
• Altering the index of inflation from RPI to CPI. The former is
  calculated with an arithmetic mean, the latter with a geometric
  mean, which is always less. CPI runs about 0.7% lower than RPI;
  a cut of 0.7% over twenty years compounds to a 13% reduction.
  
  
• Introduction of a two-tier system, with significantly lower
  payouts to new hires (see next point, re: Jill). If this follows
  the course of other two-tier schemes, the upper tier will be
  eliminated in favour of the lower, and old hires will see their
  pension slashed.
  

Jill, the next lecturer we hire. Old hires who pay into the pension
fund for forty years receive a pension of one-half their final salary;
new hires who do the same receive a pension of one-half their
*average* salary. Basing pensions on average rather than final salary
may be sensible, but to do so with no adjustment in multiplier makes
it appear that employers are using this as an excuse to slip in a
large cut. The changes are estimated to remove £450K in value over
the lifetime of a new hire's pension.

Bill, a student ten years from now. In the long run, our goal is to
keep our Universities strong for students and the country. On the
picket line last Thusday, I saw more students than lecturers.

Me. I saw lecturers cross the picket line on the grounds that they
had an appointment, and did not want to inconvenience the person they
were to meet. If you are one of them, perhaps your politeness would
extend to allowing me to retire with a decent pension.

Thank you for your consideration, -- P

I propose the following Law of Proverbs: for every proverb, there is an equal and opposite proverb. Examples:

A stitch in time saves nine./If it ain't broke, don't fix it.

In for a penny, in for a pound./Don't throw good money after bad.

What the eye doesn't see, the heart doesn't grieve over./Truth will out.

Don't throw the baby out with the bathwater./Make a clean sweep of it.What are your favourites?

# posted by Philip Wadler @ 11:05 AM 11 comments

The NSF is interested in ensuring expertise in programming languages is represented among its program directors, and SIGPLAN is encouraging researchers to apply. This video from an NSF director explains why you should consider a post at NSF.

Stack Exchange is a website for asking and answering technical questions. One part of the web site is set aside for Theoretical Computer Science. It tends to be dominated by topics in "Theory A" (algorithms and complexity), but there is a small, intrepid group attempting to establish it as a venue for topics in "Theory B" (logic, semantics, and programming languages). To encourage further participation, they've assembled a list of some of the interesting questions they've handled. Have a look, and contribute some questions or answers of your own!

I try to impress upon my students the importance of clear expression. Today's news contains an example where choice of the right word may be life-critical.

The experts reworded phrases that people found confusing, and then retested them in several sittings, including one-to-one interviews.

Prof Raynor said "avoid alcoholic drinks" was a good example.

"Our user tests have shown that the word "avoid" can cause confusion and that some people think it only means they should limit their alcohol intake.

"This phrase will now be replaced by the instruction: 'do not drink alcohol while taking this medicine', which is far clearer."

Other recommendations include changing "do not take indigestion remedies at the same time of day as this medicine" to "do not take indigestion remedies two hours before or after you take this medicine".

Another phrase, "do not stop taking this medicine except on your doctor's advice", becomes "warning: Do not stop taking this medicine unless your doctor tells you to stop."