R – OWL Assembly Generation Problem (OWLGrinder)

As the error says, it's not a real enum.

It sounds like you need reflection:

var fields = typeof(Language).GetFields(BindingFlags.Static 
                                        | BindingFlags.Public);
foreach (string item in fields.Select(field => field.GetValue(null)))
{
     // ...
}

That's assuming there are no other public static fields in the type. You could always filter by type etc.

Like object-oriented language, is rdfs:subclassOf inherits property from super class?

To say that the domain of property p is the class D means that when you have a triple

x p y

you can infer the triple

x rdf:type D

There's no notion of inheritance of a property. If you know that E is a subclass of D, and you see the triples

e p y  
e rdf:type E  
E rdfs:subClassOf D

you now have two ways to know that e rdf:type D. The first is because e p y implies e rdf:type D. The second is because you know that e is an E and E is a subclass of D, e is also a D.

What is the meaning of inheritance in RDF/OWL?

Classes in RDF and OWL are sets. When you know that E is a subclass of D, it means that every element of E is an element of D; that is, the set of individuals of E is a subset of the set of individuals of D.

Similarly for properties. If q is a subproperty of p, it means that x q y implies x p y.

Is it possible to construct object-oriented language type class-subclass inheritance with OWL/RDF?

It's not really clear what you mean here. You'd need to specify exactly what you mean by OO-langueg type class-subclass inheritance. You get a lot of the same behaviors. E.g., if you know that every instance of D has a particular, then you know that every instance of E does, too, by virtue of the fact that every instance of E is an instance of D. E.g., if you have

D SubClassOf (hasColor some Color)

then you can infer that

E SubClassOf (hasColor some Color)

so in that sense there's inheritance.

Consider following example. Are all the properties of "Lecturer" and "Student" will be available to "Person" class?

"Available" might be misleading. There's no sense in which properties are available or not available to a class (i.e., to the individuals in a class). If you have a hierarchy like:

Lecturer rdfs:subClassOf Person  
teachesCourse rdfs:domain Lecturer
teachesCourse rdfs:range Course

that means that when you see a triple

Jones teachesCourse Calculus

you can infer that

Jones rdf:type Lecturer  
Jones rdf:type Person  
Calculus rdf:type Course

The property teachesCourse is "available" to every Person, in a sense, but as soon as it is used, it means that that Person must be a Lecturer. That's really pretty similar to what you'd have in an object oriented programming language, isn't it? E.g., if you have in Java:

class Person { }

class Lecturer {
  Course[] getCourses() { /* ... */ }
}

then there can be instances of Person that have a getCourses() method. It just happens that those instances of Person must be instances of Lecturer, too.