Should n't a link like this ( http://www.icyphoenix.com/viewtopic...ingle_Post_View ) open the link like this ( http://www.icyphoenix.com/show_post.php?p=55936 ) after clicking or copying the post-number link next to the post?

No, because that is only a fragment of the url, not a component of the HTTP vars.

In other words, you see that link when clicking on single post view just because it is a JavaScript doing the job behind.