Re: Simple Components (Generic_Directed_Graph)

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On 2017-10-31 16:07, Victor Porton wrote:
> Dmitry A. Kazakov wrote:
> 
> I consider an RDF file. RDF files contain so called "triples" (subject-
> predicate-object). Each of the three can be an URI.
> 
> I consider a digraph whose arcs are subject-object (with predicate
> expressing the relation "is-subclass-of"). This graph is to store all known
> sub-class relations between URIs. It is specifically is there is a path of
> "is-subclass-of" relations between any two given URIs.

OK, that is a decision tree, a crisp tree in your case. Though usually 
weighted graphs are used, e.g. in probabilistic and fuzzy, 
intuitionistic fuzzy trees. In real-life applications such relations are 
rarely crisp. It is an inference that usually yields a probability or 
confidence measure of A in B. [In intuitionistic inference it is also 
other three outcomes A in not B, not A in B, not A in not B.]

> Certainly an RDF file can have a subject or object more than once (and even
> many times).
> 
> RDF is a mean to store logical (semantic) relations online in a portable
> way. A URI may be not a page of the Web, but an abstract object representing
> any concept (for example, we can have an URI whose meaning is "cursive font"
> or "revolution in Ukraine" or "computer science", just arbitrary, this is
> the power of RDF).

No, this is weakness. Any = nothing.

> Is my solution to use Map to map URIs (you can think of them as strings) to
> accesses to empty records (representing graph vertices) a good programming
> style?

Rather a poor choice. There is no advantage in having copies. One could 
have them in order to gain something, e.g. performance or design clarity.

> I do not need to map a graph vertex into a string, but I need to map a
> string into a graph vertex.

No, it is a set of vertices implemented as a map because you have 
trouble using a string for searching the set.


-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de