When a good idea produces fine software

This is a good computer adaptation of a learning game which can be fascinat ing to use both for young and old BBC Micro users.

First of all the user is asked to enter their name, and then to think of an object for the computer to guess. When you have thought of your object the computer asks if it is animal, vegetable or mineral. Suppose you had thought of a cat, then the response here would be animal.

Being a fairly smart computer the next question you are asked is: "Has it got four legs?" In this case you would say yes, and the computer thinks for a moment and then asks: "Is it a cow?".

This is because until you have taught the computer a few more facts about the world, the only four legged animal it knows about is a cow. So it gives up guessing when you say "No", and asks you instead what animal you were thinking of.

Now for the tricky part! The com puter rather sweetly asks "Now please type in a question that would tell the difference between the following: Cat - Cow".

Just when you are feeling that you have outwitted the stupid machine you have to think of a good difference between the two objects.

For example, "Does it live outside?" and "Can you keep it as a pet?" could have debatable answers! In this case you could settle for: "Does it purr?" The computer responds with "Thanks for teaching me more", and tells you how many animals, vegetables and minerals it knows of now.

If you have another go, and think of another animal the computer will ask first, "Has it got four legs?" then if you say yes will ask, "Does it purr?". From here it again builds up a store of knowledge about objects and significant differences between them, which after a few goes develops into an appealingly interesting exercise.

The computer gradually learns more and more about the objects and challenges you to increasingly more subtle depths of thinking about them. The program allows you to save questions and objects too, so that all your hard thinking from one session can be used again without beginning from scratch.

This is one of those rare programs which takes a good simple idea and translates it into an equally good and easy to use piece of software.

Jane Jackson