[gjm11]

No, the invention here is not a sentinel. It's having a bunch of things each of which has two or more next-item pointers so that you can traverse the list in two or more different orders. For instance, this would cover any doubly-linked list.

... Which is pretty strange, actually, since the patent itself references prior art involving doubly-linked lists. Maybe that's why they had a separate claim for a list with three "next" pointers in each node. I have no idea why claims 1, 3 add 4 weren't thrown out by the examiner given that everything they describe is done by every doubly-linked list implementation anywhere ever. (Claim 2 looks obviously not novel to me, but it's not quite such a slam-dunk as the others.)

So, anyway. The patent is preposterous. It isn't a patent on The Linked List. It doesn't involve sentinels. It doesn't cover any singly-linked list. It does cover any doubly-linked list (which is one reason why it's preposterous). The author of the OP is right about the patent's preposterousness but wrong to describe it as "patent[ing] a linked list". monochromatic is right that the patent isn't a patent on the linked list, but arguably wrong to think this proves the original author is a twit (perhaps s/he knows perfectly well what the patent purports to cover, but preferred terseness to precision). rtperson is wrong to say that the patent is about "a standard linked list with sentinels", wrong to be obnoxious about it, but probably right that there's prior art in CLRS at least for claims 1,3,4.