How to State Facts or Properties and Use Them

Putting an "EmptySmallSquare" after an expression has the effect that from then on the expression will evaluate to "True".

Special attention should be paid to the property known that is defined in the language: something is known if it is either given or it has been defined. Many computation rules are implemented in such a way that their applicability depends on whether something is known or not. By explicitely stating, that something is given one can then force the rule to be applied.

For atomic objects defined is intelligent enough to check whether the object is known.

For symbols that have no value, like e.g. "W"

we can "make it known" by assuming it as "given":

Even more: