The notion of solvability in the call-by-value λ-calculus
is defined and completely characterized, both from an operational and a logical
point of view. The operational characterization is given through a reduction
machine, performing the classical β-reduction, according to an innermost strategy.
In fact, it turns out that the call-by-value
reduction rule is too weak for capturing the solvability property
of terms.
The logical characterization is given through an intersection type
assignment system, assigning types of a given shape to all and only the
call-by-value solvable terms.