Is there a way to visualize the requirements in a graph showing links among the artifacts?

You can analyze traceability relationships between requirements or other life cycle artifacts directly in RRC through the table view (inserting columns) or the tree view which allows you to expand hierarchy of traceability to see end to end trace relationships. In these views you can see the requirements artifacts and linked information at the same time. We also can produce trace reports.

We've put out an early visual traceability visualization add on (incubator) that you can use now that allows you to see trace relationships in a tree diagram. See the following link:
https://jazz.net/blog/index.php/2011/07/07/introducing-a-graphical-traceability-explorer-for-rational-requirements-composer/

We are working to expand on more options for this visualization feature and plan to release it in RRC properly in the next functional release in 2012. See the latest RRC milestone here on jazz.net for more up-to-date information.

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Jared Pulham
RRC Product Manager