In a Syntax-Directed Definition, a synthesized attribute at node N is computed from:
A synthesized attribute is computed from attributes associated with the children of the node (and, depending on the notation, values already associated with the production's symbols), flowing information upward in the parse tree.
In a Syntax-Directed Definition, an inherited attribute at node N is computed from:
Inherited attributes obtain information from the parent or siblings of a node. In an L-attributed definition, inherited attributes have the additional left-to-right dependency restriction.
An SDD is S-Attributed if:
An S-Attributed Syntax-Directed Definition contains ONLY synthesized attributes, allowing evaluation during bottom-up (LR) parsing.
An SDD is L-Attributed if every attribute evaluation rule A -> X1 X2 ... Xn computes inherited attributes for Xi using ONLY:
L-Attributed definitions enforce left-to-right dependencies: inherited attributes of Xi rely only on parent attributes or attributes of symbols strictly to its left (X1...Xi-1).
Which statement accurately describes the relationship between S-Attributed and L-Attributed SDDs?
Since S-Attributed SDDs contain zero inherited attributes, they vacuously satisfy the L-attributed restriction (left-to-right dependency). Thus, S-Attributed is a strict subset of L-Attributed.