This problem is about reachability, which is an important concept for automatic memory management. Given a name, the set of reachable memory locations includes those that can be accessed directly or indirectly using that name. For instance, for the following expression, the reachable memory location for name c is loc:0:

The value of the reachable expression is a string value that starts with an open brace ‘{’ and ends with a close brace ‘}’. The string value contains a comma-separated list of reachable locations. Some examples appeared previously.