Sean Clarke - Well, in my first reply I did give an example of the type of things I might want to do. But I'll try to start a separate discussion.

David J M Park Jr - This is a thread about discovering new entities in the Wolfram Entity Framework. Your question is a more general programming question, and you would probably get the best answer by posting it as a separate thread so that people who do differential geometry with Mathematica will be able to find it. Please post this as a new thread.

Mark Linehan - Sorry about the wait. I thought I had posted a response on Friday.

You don't really add entities onto the entity framework. You could create your own framework of course and use it side-by-side with the existing one.

No, EntityClasses are not like a subtype of a type. They are really nothing more than a list of entities. I think you might be trying to think of the entity framework like it was a type system or a object hierarchy in OOP. The EntityClass for European countries is just a list of Countries that are all in Europe. In most uses of the word "Subtype", if A is a Subtype of B, then you can use A wherever you'd use B. That's certainly not the case here. An Entity type is an abstract category, like a bridge or a person. An EntityClass is a list of entities of a certain type. They are fundamentally different kinds of objects.

"ctrl =" is meant to be useful in general. It's a natural language query tool. It won't be perfect."ctrl =" can return many different kinds of things - Not just Entities.

• Portrait of Titus defaults to a query for the picture of the person named "Titus"
• "Great Fish Market" returns an Entity for "Great Fish Market". An Entity and the picture associated with an Entity are different things. The predictive interface (the grey bar appearing after your output), will show you different properties you can query from your Entity.

• "The Bride" by default gives a movie and a couple of other options. No, the list of options is not exhaustive. It cannot be exhaustive over every possible interpretation of the word. You can use Interpreter or SemanticInterpretation to get an interpretation for "The Bride" that corresponds to an artwork like this:

  Interpreter["Artwork"]["The Bride"] Interpreter["ComputedArtwork"]["The Bride"] SemanticInterpretation["The Bride", Entity["Artwork", _]]

I am not familiar with the piece of art that this refers to. Searching online didn't make it clear either. So it's probably unlikely that the system will be able to infer it too.

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.