I am not aware of any word processor that would insert an actual minus glyph when the 'minus' key is pressed. In this instance, the author explicitly specified a minus codepoint.

You're probably right. As soon as I hit 'Submit' I regretted having used the term 'sign'. It's better to distinguish between keycaps, scancodes, character codes and glyphs.

It's a hyphen. A standard keyboard layout has no minus sign, not even in the keypad. The author of the book explicitly specified a Unicode minus sign wherever a hyphen should've been because "I try to avoid using direct ascii hash codes because some ereaders can misinterpret them"

Addendum: It turns out the author used the minus sign instead of the hyphen. That (a) looks wrong on the page, (b) breaks screen readers, (c) confuses readability scores and (d) makes this not news.

Actually, it looks like Amazon is the typography police. For whatever reason, the book seems to use en-dashes instead of hyphens (check the preview on Amazon). That is an abomination. Where the message changed from "please replace en-dashes with hyphens" to "don't use hyphens" is anyone's guess.

As soon as you put a second point on the screen there are 2 possible combinations for those two points:

That's exactly what I tried to say: "or more accurately, two corners of a rectangle, with no way of knowing which two."

And just like back then, they can still only recognise up to two points (or more accurately, two corners of a rectangle, with no way of knowing which two. But that's probably enough for a zoom or rotate gesture.)

It's still commonly used in digital whiteboards, e.g. in classrooms. There are even companies that retrofit IR touch frames on non-interactive displays. It's finally dying in that market because Microsoft now requires full multitouch capability for modern Windows compatibility.

It's a Ponzi scheme! Pyramid! Tulips! Pet rocks!

Tim Minchin put it best: to assume that a one-in-a-million thing is a miracle is to massively underestimate the total number of things there are.

"MIT Develops Holographic, Glasses-Free 3D TV"? Only if by "holographic" you mean "not holographic"