|
|
|
This famous
drawing of Escher represents a building but a building that is impossible to
build. In the analogy it represents first order logic. With first order logic
it is possible to make definitions that are impossible to construct.
|
|
An example: if
the result of a query is:
|
|
T1 or T2
|
|
where T1 and T2
are triples. T1 might be true or T2
might be true but which one is true??
|
|
Two points
however:
|
|
* it is an analogy and an analogy never fits
completely
|
|
* this is not an attack on first order
logic: it is possible to make fine buildings too with first order logic;
besides first order logic is a monument of science with huge merits,
certainly in the field of mathematics.
|