Checking your computer is configured correctly I

Checking your computer is configured correctly I


Web based instruction

Most of the software and instruction on this site should run on any computer with any web browser, without any special configuration.

So most Users can stop reading this page at this point.

Sometimes there can be issues with symbols.


Symbolic logic uses symbols, in particular (unicode) ∼ ∧ ∨ ⊃ ≡ ∀ ∃ ∴ or (html) ∼ ∧ ∨ ⊃ ≡ ∀ ∃ ∴ . If you cannot see these, that certainly is a problem to be solved. The solution is a) use a more modern web browser, or b) use a different web browser, or c) get a more modern computer and try (a) and (b) again.

[What is happening here is that that the symbols are in unicode and each symbol has its own unique unicode. However, particular fonts on a computer display only a relative few of 60,000 odd unicode characters. If a particular font cannot display a symbol, changing fonts to a different font may help (and some host computers automatically do this). The web browsers can display many unicode symbols, and they normally do so by means of an html conversion. Each year, the browsers can display more and more. Our logical symbols are commonplace mathematical symbols so they should be displayed. But if you have a really old browser.... you may see either nothing, or a default character like a square box ▢.]

You could also look at Writing Symbols and Alternative Symbols.

Even more on (Special) Symbols

Wikipedia is pretty good on this (for it is a problem for them also). See Help: Special Characters (especially the section on Displaying Special Characters). One point they make is that the default font for the Internet Explorer browser is Times New Roman and that font does not contain much Unicode. A work around for Internet Explorer is to change the default font to something else, say Lucida Sans Unicode-- they give the details. And Wikipedia further asserts

"Special symbols should display properly without further configuration with Mozilla FirefoxKonquerorOperaSafari and most other recent browsers."

Google Chrome should be added to that list.

Java (Java applets and downloadable Java applications)

We are running less and less Java applets on the site (there may be none by the end of 2013).

But with the few that there are...

Basically the problem lies with the running of Java in a Web Browser such as Safari, Firefox, Chrome, Internet Explorer, etc. There was a time, maybe 10 years ago, when the running of Java Applets in Web Browsers was easy and trivial. (We all remember those 'eyecatching' Java Applet animations of people waving flags and digging ditches.) But times have changed. Basically, Java would not load fast enough to retain the attention of Users with short attention spans (i.e. all of us). So the Web, and in particular Apple and the late Steve Jobs, are moving on. iPads and iPhones won't run Java at all, and, ordinary Macintoshes can, but with some difficulty (especially for those using Mac OSX Lion, Mountain Lion etc.). 

Java Applets

A few of the tutorials run Java Applets. You need to be able to see these. We will show some in the next page.

You need to be able to see these (with most modern Web Browsers either you will be able to or the Browser itself will advise you what needs to be done).

One small item you can check straight away is that your Web Browser needs Java and Javascript enabled (almost certainly they will be, but it is possible, for one reason or another, that they are not). Find the Preferences for your Browser (it will be on one of the Menus, different places for different Browsers), then it needs to look like this:

Special considerations for the Macintosh, especially OSX 'Lion' 2012

It is increasingly difficult to run Java on a Mac. So if you are using the Macintosh Safari Browser you may face various issues (which to some degree can be avoided by using a different Browser, say Chrome). The first problem is that modern Macs take a very long time to launch Java, often a minute or more (and then the Applets themselves take 20 seconds or so). So the User, you, can face much looking at blank pages. Then Java is not typically installed in modern Macs, so it has to be installed (the Mac will prompt you to do this). But then, in Lion, the biggest problem of all. Safari in Lion will tell you that  you need Java and ask you if you would like it to get it and install it, which it will then do. But, it does not switch it on, and it cannot be switched on in Safari. To switch it on you have to go to the program Applications->Utilities->Java Preferences and launch that program, then check the Enable applet plug-in box. The result should look something like this

[Steve Jobs wanted rid of Java, from Browers, iPhones, iPads etc. Even so, these installation hoops for a Java Plug-in on Safari are an inelegance that would have offended him mightily.]

Downloadable Java Applications

The Deriver application program, and the applets, run on the 'Java Virtual Machine' or 'Java Runtime Environment' on the host computer (your home computer). But if your Java Runtime Environment is out of date, especially way out of date, that offers an invitation to erratic behaviour. Windows and Macintosh machines, and probably others, automatically update their JREs. But you can refuse that update (and maybe some Users do not understanding what a Java Runtime Environment is).

But if your version of Deriver is doing something odd, like not displaying the symbols properly, check that your JRE is up to date. Check


Continue to Checking your computer is configured correctly II . This one has real Java in it, so it could take 30 seconds to load or, if things are not working properly, it may remain blank.