# Revision history [back]

It seems you hit a bug with gap interface (though i am not able to explain further):

sage: G.inject_variables()
Defining u0, u1
sage: gap(u0)
f1
sage: gap(u1)
TypeError: Gap produced error output
Error, Variable: 'u1' must have a value
executing \$sage5:=u1;;

sage: u1.value()
a + 1
sage: gap(u1.value())
a+1


It is not clear to me what kind of value is gap requiring. I tried with an embedded number field, but i get the same error.