Question

In Syntax Directed Translation (SDT), an attribute is called "inherited" if its value at a node in the parse tree is defined in terms of attributes at:

• A. Its children only.
• B. Its parent and/or its siblings.
• C. Its left child only.
• D. Its descendants only.

Hint:

A grammar where every attribute is synthesized is called an S-Attributed grammar. A grammar that allows both synthesized and certain types of inherited attributes (usually from the left sibling) is called an L-Attributed grammar.

Answer 1

The Correct Option is B

Concept: Syntax Directed Translation involves attaching rules to grammar productions to compute values (attributes) for nodes in a parse tree.
• Synthesized Attributes: Values are computed from the attributes of the node's children. These flow "up" the tree.
• Inherited Attributes: Values are computed from the attributes of the node's parent and/or its siblings. These flow "down" or "across" the tree.

Step 1: Defining the flow of information.
Attributes allow the compiler to pass information during the parsing process. Inherited attributes are useful for passing context-dependent information.

Step 2: Identifying the source of Inherited values.
When a value comes from above, it is provided by the parent. When a value comes from the same level, it is provided by a sibling. This is typical for type checking and identifying variable declarations.

Step 3: Conclusion.
Because the definition excludes children and descendants. Option (B) is the only choice that matches the "top-down" or "lateral" nature of inherited attributes.