This page used to be called "Links to Istanbul", but somehow the number of links decreased until none of the worked any more. So what is left are a few impressions of this city. I wrote this after a short visit there in 1996 or so. This was before I had been to other big cities like New York, so the numbers might not impress you that much.

Still, this city has a very strong athmosphere to it and it is certainly worth a visit.

The Ackermann Function is a simple recursive function that produces incredibly large values with very simple inputs. Here is a short description, a way to calculate some of its values using simple formulas, and a very large number.

Some time ago, I thought I needed a shift (perspective correction) lens. But the original Nikon PC lenses are extremely expensive (at least for me, doing photography only as a hobby), so I bought a Russian Arsat 2.8/35 mm shift lens, which is much cheaper. Here is some data about that lens, including a table of how far you have to stop down to avoid vignetting.

What's the point of comparing two black-and-white films that are not available anymore? Somebody emailed me with that question several years ago. It was still interesting to do this comparison, and who knows when you might get into an argument between b&w photo-geeks and need a source to back you up?

This test was invented by Alan M. Turing (1912-1954) and first described in his 1950 article Computing machinery and intelligence (Mind, Vol. 59, No. 236, pp. 433-460).

Please note: This was written many years ago, after reading the article Subcognition and the Limits of the Turing Test by Robert M. French. AI is not my field of research, so take this as a bit of speculation, nothing more. I am keeping the article here because of the number of links that are pointing to it, and for historical reasons (this was the first thing I ever published on the Internet, back in 1996 or so).