Why do circular references and recursion make my program fail?

Question

I wrote this simple Prolog program.

man(socrates).
mortal(X) :- man(X).
immortal(X) :- immortal(X).

I asked it the usual questions, such as

Answer 1

Using tabling with XSB:

:- table foo/1.

foo(X) :- foo(X).

bar(X) :- bar(X).

and then:

| ?- [tabled].
[tabled loaded]

yes
| ?- foo(1).

no
| ?- bar(1).    % does not finish