Logic for Computer Science

Today, in my reading,  I came across the following:

The only kind of logic necessary in computer science is the predicate calculus, used in the rigorous yet "informal" way of the working mathematician, but perhaps reformulated and extended by useful theorems in the direction presently being investigated by Dijkstra. Formalisms requiring a separate "proof system" or bearing the "formal logician's trademark" should be viewed rather critically.

R. T. Boute, On the Shortcomings of the Axiomatic Approach as presently used in Computer Science, Proc. IEEE COMPEURO 88, System Design: concepts, methods and tools, pp. 184-193, April 1988.

[By the "formal logician's trademark" Boute means the turnstile symbol.]

I think I can do this, but ...

I came across the following sentence in one of Paul Graham's essays:

I think I can do this, but I have to figure out what I'm trying to do before I can figure out whether or not it's possible.

This might not make strict logical sense but it nicely sums up one of the problems facing software developers.

Update on Mon 2006-04-03 by Tristram Brelstaff

This is a modern variant of:

How can I know what I think till I see what I say?

E.M.Forster, Aspects of the Novel, 1927.

Traces of Wood Pigeon Take-Off

As we were setting off on our walk yesterday I noticed a couple of wood pigeons scratching about in some dried leaves on the path on the other side of the road.  One of them flew up into a tree and as it took off the leaves around it were blown outwards by the force of its wing beats leaving a roughly circular clearance in the layer of leaves.  Then the second one took off leaving another clearance. 

The Return of the Shoveller Ducks

We are currently in the middle of the first cold spell of the winter.  Here in the south of England that just means a run of nights in which the temperature drops below freezing point.  Yesterday afternoon we thought it worth going round the university lakes to see if if there were any interesting migratory birds that had been pushed down from the north by the cold weather.  Sure enough, there were 20 to 25 shoveller ducks in two rotating groups on the large lake.  I seem to remember seeing a small number of them, 6 to 10, on the lake a few weeks ago, but the cold weather had certainly brought in more.

The Effects of Firefox and Open Office on Microsoft

Yesterday I came across the following:

I think a lot of people misinterpret the importance of Firefox.  Firefox is not important because it may replace or substantially reduce the Internet Explorer monopoly.  Firefox is important because it forces Microsoft to innovate.  The Internet Explorer team has been reformed and work is starting on the first serious upgrade to the product for years. This is a good thing for everbody, whether you like Microsoft or not.

Simon Johnson (http://www.ckwop.me.uk/)

This reminded me of something I read about the importance of OpenOffice to Sun: they are using it to compete with the vastly profitable Microsoft Office so that Microsoft will be less able to subsidise their loss-making server software which is displacing Sun from their specialist market.  I think it was in an essay by Joel Spolsky or Paul Graham that I read this .