Within the Wolfram Language facilities, what is the best alternative to creating one's own interactive data base of knowledge on some subject?

That's a very large question. If you can provide more specifics, that would help. I would again ask that you post this as a new question. It is in a sense most certainly related to this one, but you'd be better served by new thread and it would help keep this thread on focused on the original topic should more questions arise about using the Entity framework, esp with respect to finding Entities. This thread has already addressed many topics as it is and your question is a very broad one.

"Interactive Base of Knowledge" is a very vague term that could mean lots of things. Are you looking to make a framework that's like parts of the Entity Framework? If so which parts? It's a very large framework. You of course have to pay attention to how you structure the relationships between kinds of objects.

Any symbolic program is an interactive base of knowledge about the symbols it uses. The key of course is how to best structure these programs. That depends very heavily on what you want to do. Having a small and specific case will help someone answer your question.

This is a very helpful thread. Thank you.

1. Ignore the existence of "ToEntity" for right now. It only handles a select class of objects. These are the objects which have concrete representations in Mathematica and in the entity framework, which is a tiny, tiny fraction of the total number of entities.

• You can get Entities in many different ways. One way is through the curated lists of Entities called Entity Classes. See an explanation of them below.

• You can also get specific Entities using "Ctrl" + "=" for free-form input. For example if I wanted Chicago as a City I would type:

"Ctrl" + "=" Followed by Chicago

If instead I wanted Chicago as a Movie, I click the ellipsis just to the right of the result and a menu with alternate interpretations appears. Movie is one of the options available.

• You can use Interpreter:

  Interpreter["City"]["Chicago"]
  
  Interpreter["Movie"]["Chicago"]
  

• You can use SemanticInterpretation:

  SemanticInterpretation["Chicago"]

  This gives the default interpretation for "Chicago" which is as a City. Instead you might as for every possible interpretation of Chicago:

  SemanticInterpretation["Chicago", AmbiguityFunction -> All]

1. Types and Classes are different. A type is fundamental kind of a thing such as a "Country", or a "Movie", or a "Person". An Entity expression has two arguments. The first argument is a string of what type it is. The second argument is a string which uniquely identifies a specific instance of that type. For example the Entity expression for Elvis Presley is:

Entity["Person", "ElvisPresley::2kzg4"]

There could be multiple Elvis Presleys, so there's a unique tag added to the end of the second string. An EntityClass is a curated list of a specific kind of Entity. For example, EntityClass["Country", "Europe"] is a curated list of Entities of type "Country" that are located in Europe. And EntityClass can be turned into a list of Entities using EntityList. There is no Entity type specifically for countries in Europe. There is only a Entity type for countries in general. However there is an EntityClass which lists which countries are in Europe.

1. Basically, No. The inner workings of entities are really complex and you don't want to have to reimplement all that. If you want to incorporate outside data sources, it's best to do so alongside the framework, not using it.

2. You don't. You could write your own function to do the essentially the same thing but it wouldn't integrate with the entire framework.