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If I have category pages for my site; is it better to use http://example.com/category/category or just http://example.com/category? Also, I'm creating a new section of the site; a resource center. Should the URLs of the pages in the resource center be http://example.com/learn/page or just http://example.com/page What are the reasons for the better choice?

By 'index rules' I mean the stipulations that constitute whether or not a given page will be indexed. If you can see them - how?

For example, from http://www.dog.com/toys to http://www.dog.com/chew-toys. In my situation, the main purpose of the 301 redirect is to replace the page with a new internal page that has a better optimized URL. This will be executed across multiple pages (about 20). None of these pages hold any search rankings but do carry a decent amount of page authority.

The crawl diagnostic has found errors for pages that do not exist within the site. These pages do not appear in the SERPs and are seemingly dynamic URL pages. Most of the URLs that appear are formatted http://mysite.com/keyword,%20_keyword_,%20key_word_/ which appear as dynamic URLs for potential search phrases within the site. The other popular variety among these pages have a URL format of http://mysite.com/tag/keyword/filename.xml?sort=filter which are only generated by a filter utility on the site. These pages comprise about 90% of 401 errors, duplicate page content/title, overly-dynamic URL, missing meta decription tag, etc. Many of the same pages appear for multiple errors/warnings/notices categories. So, why are these pages being received into the crawl test? and how to I stop it to gauge for a better analysis of my site via SEOmoz?