What are the best (more or less mature, supporting more advanced logic, having acceptable performance, scalable to some extent) open source Semantic Web libraries and tools (RDF storage, reasoning, rules, queries) for Python nowadays? Historically Python tools (cwm) were among the first to appear, but it still seems that everyone uses Java back-ends for performance and Python as mere client if at all. My purpose is to learn the technology and maybe some future use in production system if it proves itself up to the task. The task is not yet defined, but as I see it its building a knowledge base, linked with some external resources, and customized facet-navigable web front-end.
If some building blocks based on Python are not good enough, then what is the suitable piece from Java/C/C++/whatever world.
Typical stack is also of interest, if there are one or two clear winners.
Thanks.