ICTP Workshop 2007/Some suggestions for the semantic extension

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{{#titlehere:}} Please note that the present pages on the ICTP workshop were obtained from a mediawiki used during the workshop. There may be a number of links that go to missing pages, and other inconsistencies. Much of it is also very informal, and should be seen as workshop notes!

1 What is a category and what a property?[edit]

1.1 Categories[edit]

Remember that a category is a sort of data type (a class).

If you can say "X is a Y", then probably Y is a good candidate for being a category.

If you want to say that "Marco is interested in Flash", then you should NOT put Marco in the Flash category, as it is incorrect to say that "Marco is a Flash".

In traditional wikipedia, saying [[ICTP Workshop 2007/Category:X]] often means "this is a page about X". In semantic wikipedia, I would suggest to restrict the use of categories to say "is a" (link in Marco's page we say "Marco is a Teacher".

1.2 Properties[edit]

The reason why in traditional wikipedia [[ICTP Workshop 2007/Category:X]] often means "this is a page about X" is that essentially you have no way to express relations, other than using explicit links or aggregating through categories.

In the semantic wiki, you have typed relations. So if yo want to say that you like Jazz, do not put Jazz as one of your categories, but rather create a relationship by writing in your page:

I like listening [[ICTP Workshop 2007/likes::Jazz]].

And remember that your property will show up in your page, so do not leave it alone! If you write

[[ICTP Workshop 2007/likes::Jazz]][[ICTP Workshop 2007/likes::Movies]][[ICTP Workshop 2007/plays::Football]]

you will have a page that makes sense to a machine but not to a human, because it will loook like this:


Instead you should write:

I like to listen to [[ICTP Workshop 2007/likes::Jazz]], to watch [[ICTP Workshop 2007/likes::Movies]] and to play [[ICTP Workshop 2007/plays::Football]]

From the point of view of the machine, the info is exactly the same as above, but now to a human reader the page looks like:

I like to listen to Jazz, to watch Movies and to play Football

1.3 Boolean properties[edit]

Since the object of the relationship expressed by the property gets printed on the page, it in general NOT a good idea to have properties like

[[ICTP Workshop 2007/has Image::yes]]

since it renders on the page showing

yes no

which does not make much sense for the reader...

In my opinion it is better to use a syntax like:

[[ICTP Workshop 2007/[has image::[[ICTP Workshop 2007/Image:MarcoRonchettiSmall.jpg]]]]

(the object of the "has image" property becomes the image itself).

As an alternative, you can define the has image property of being of type text, and use the syntax

[[ICTP Workshop 2007/has Image::yes| ]]

which would assume the vaue yes for the property, but would show only a space instead of showing the annoying "yes".

1.4 Slides of Marco's talk[edit]

They can be found on http://www.slideshare.net/ronchet.