h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

amused(),

AND is analogous to multiplication
OR is analogous to addition

AND is neither addition nor multiplication, but behaves in the same way as multiplication if we take true as 1 and false as 0.

OR is neither addition nor multiplication, but behaves in roughly the same way as addition if we take true as 1 and false as 0.

Hope that clears it up.

The OR analogy to addition is only 'roughly' similar as one never gets a bigger answer than 1. A OR B is true if 'At least one of the terms is true' so it is true when both are true. Using 1 for true gives 1 OR 1 = 1, whereas the naive use of addition will give 1 + 1 = 2 (or 10 in binary)

One way of getting your head around the use of logical sum might be the following:
In the case where both terms (or 'more than one' when considering more than two terms) are true, the sum of terms is also true not because the sum of the 1's is naively 1, but because the sum is greater than 0.

Whether this is worth adding to any logic entry is debatable.

In reply to those of you that are confused, OR is addition, AND is multiplication (sort of), and not the other way around. The correspondence makes it as easy (or as hard) to manipulate Boolean expressions as it is to manipulate any other algebraic formulae.

Gnomon, what on earth makes you think it should be called a Venn-Euler diagram? I note that Euler (1707-1783) died before Boole (1815-1854) was born, and long before Venn (1834-1923) conceived the diagrams, while extending Boole's work. I know he was prolific, but was Euler clairvoyant?

I can make no progress with this entry, as I have to define my every word. The existing entry on Boolean Algebra does none of this, so referring to it is no help. This entry, and all those which would have linked to it, will be withdrawn from peer review.

As for the diagram, I offer this. To get diagrams done for entries, I have asked of certain subeditors and certain artists, and have even offered my services as an artist, all to no avail. So instead I have done rather a lot of work to ensure I know that the spaces I reserve for text are large enough. I do not intend to do any more. Have all the existing EG entries been subject to such scrutiny? (If they had, why is it that I discover &minus fails on some browsers, table captions fail in some skins, etc, and yet there is nothing in the 'help' pages about any of these things?)

I can only test the diagram using IE. However, I have tested it in Alabaster, Goo and Brunel, with screen resolutions of 640x480, 800x600 and 1024x768, and in each of those cases with normal size text and larger size text. The diagram remains intact in all 18 cases, so I think that all is well there. Furthermore, I have engineered the diagrams to use only ROWSPAN and COLSPAN dimensions for the text boxes, so that the generated table pixel dimensions are created by h2g2 and not my browser (I think). I am extremely doubtful that other contributors test their entries to anything like this extent.

>>what on earth makes you think it should be called a Venn-Euler diagram?

I was taught that Venn diagrams may have circles entirely inside other circles, circles non-overlapping, but when the circles overlap in such a way as to show every possible combination of the inputs, it is known as a Venn-Euler diagram, since Euler and Venn invented them independently.

>>I can make no progress with this entry, as I have to define my every word.

Not every word. Just enough to make it readable by intelligent average readers (an oxymoron?).

>>As for the diagram

I was told that:

1. If I draw my own diagram, the editors will get it converted into a blob. I haven't tried this.

2. Constructing tables using colspan etc to make them look like pictures is not acceptable in the Edited Guide. I know for a fact that Netscape 4.7, the browser I used until last Friday, does not display such tables correctly.

>>Have all the existing EG entries been subject to such scrutiny?

I attempt to check every entry in which I am even vaguely interested for accuracy, grammar, spelling and ease of understanding. It's not a personal vendetta against your entries. It is intended to make them more likely to be picked by scouts. I'm not a scout myself, so you are welcome to ignore my advice, but taking it will make the entry more likely to be picked.

>>I am extremely doubtful that other contributors test their entries to anything like this extent.

I am not aware of any other contributors using tables in this way in edited entries, since it is frowned upon.

I am still baffled by the thought that Euler used diagrams to illustrate anything to do with Boolean algebra, which was not invented until after his death. I do not deny that Euler might have drawn circles on occasion.

If as you say the subeditors will get my diagram made into a blob, there is nothing to do. If they do not, then why are they unacceptable in an edited entry? I can find no such rule anywhere in the Guidelines. I dare say that some browsers which do not work very well also do not work with my entry. As you said in F48874?thread=349355&skip=5 that you were using IE6 last year, are you just choosing an example of a browser which fails?

My remarks about scrutiny and extent of testing really hinge on previous uses of tables. With yourself and Pimms, it was found that table captions do not show up in Brunel, and in fact Pimms made a bug report. What I am getting at is did this not get noticed before, and if not, why not? If it was noticed, why no mention on the help pages, or would that just be too helpful?

As to the average reader, well it seems that they form cabals and hound people off the site, or at least, some do at the moment.

Sorry OH if the criticism seems overwhelming. The reason is that the subject matter you are most interested in imparting is inherently difficult to explain easily to people unfamiliar with it.

Gnomon, I am constantly impressed by your selfless dedication to assist other researchers improve their entries . And you write some pretty mean entries yourself.

I think I can say we only offer criticism because we are interested in the subject you are writing about and would like to see it in the EG

Pimms

Old Hairy, up to last Friday I used IE6 in work and Netscape 4.7 at home. But I'm trying out Mozilla at the moment, so I use it both at home and in work.

When the "table art" style of picture was first invented (using Tables with very small cells to simulate bitmaps) I contacted Mark Moxon, the editor of the site, and Jim Lynn, the technical guru, to check whether they were acceptable. The response was that they were ok for personal guide entries, but should not be use in Edited Entries. I've never seen that added to the official Guidelines.

I have been discouraged from writing entries on many topics because of the inability to add diagrams. I was told that some sort of an agreement has been reached about them, but I don't know exactly what it is. I'm working on an entry at the moment which would be greatly enhanced by the addition of about 20 diagrams, but I very much doubt that I'll get them.

It was very nice of you, and them, not to tell me of this decision about 'table art'. Where are the relevant threads?

I did tell you, just now. It might take me a while to find the thread, because it was about two years ago.

"I was taught that Venn diagrams ..."

That's not the way I remember it. The whole lot were called Venn diagrams for ages. Then someone pointed out that Euler (and Leibniz) had used the same sort of diagrams - incidentally the diagram I've seen of Euler's also only had non-overlapping or totally enclosed circles! The belated inclusion of Euler's name was to correct an unfairness but without wiping out the one claim to fame which Venn had. Any distinction between diagrams which happen to end up one way being Venn while others are Venn-Euler strikes me as being (a) daft and unnecessarily confusing (b) some sort of retrospective rewriting of history since the whole lot *were* called Venn for a very long time and no-one thought the circles weren't allowed to overlap if that's the way the data turned out.

Poor old Euler. Brilliant, innovative, crucial in the history of maths . . . and Stephen Hawking didn't even give him a mention.

There was a mechanic called Euler
A ceaselessly brilliant old toiler
It saddened him when
They named after Venn
His patented logical boiler

Old Hairy, on the subject of table art:

I asked Jim Lynn, the technical DNA person, and Mark Moxon, the then Editor of h2g2 about the technique of using tables to simulate images.
I was asking about the technique in general. I didn't ask whether it would be acceptable in Edited Entries.

Jim Lynn's reply:

"It's not portable, so I'd advise against it. It would make displaying articles on low-bandwidth devices very slow or impossible.

It probably won't work on all browsers, either.

Generally a bad idea, IMO."

Mark Moxon's reply:

"If those photos are legal, then there's no problem. However, for anything remotely large it's going to be a very, very inefficient way of storing them, so I'd stick to small pix.

Up to you. It's up there with ASCII art with interesting ways of implementing graphics, and in the same way, copyright material will have to be removed whatever format it's in, but it doesn't bother me, to be honest."

There's a conversation which discusses the technique at:

F19585?thread=124216

I remember we used to call them "Vennular Diagrams" in school because we were unaware of the pronunciation of "Euler", which is nicely explained by Recumbentman's pome.