I’m having trouble with a generic phrase that takes relations of unknown types. In the example below, I get a Problem message about the phrase “x relates to an L by G”. If you change the codomain of the relation from things to a non-object value kind like numbers, everything works. Is this a bug? I’m not really sure what is and is not allowed when it comes to relations and kind variables, since I can’t find any relevant discussion or examples in the documentation.

```
Foo is a room.
Blog relates various rooms to one thing.
To decide whether (F - relation of K to L) is compatible with (G - relation of value of kind K to value of kind L):
let the domain be the list of Ks which F relates;
repeat with x running through the domain:
if x relates to an L by G:
let y be the L to which x relates by F;
if G does not relate x to y, decide no;
decide yes.
When play begins:
say "[whether or not the blog relation is compatible with the blog relation]."
```