User talk:Tromp

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Welcome to the Wikipedia[edit]

Here are some links I thought useful:

Feel free to contact me personally with any questions you might have. The Wikipedia:Village pump is also a good place to go for quick answers to general questions. You can sign your name by typing 4 tildes, like this: ~~~~.

Be Bold!

Sam [Spade] 12:10, 9 Oct 2004 (UTC)


If you could please add a copyright tag to your image, visit Wikipedia:Image_copyright_tags for all of them. Thanks --Admrboltz 4 July 2005 07:30 (UTC)

Invariance theorem[edit]


I took a look at the article on the invariance theorem in Algorithmic information theory, and as you see, it needs some work. Apparently the original editors simply lifted the definition out of Planet math, which might be better than nothing.

As I recall, the statement, an informal proof, and a formal proof appeared in Li and Vitanyi's book. Since you are in Paul Vitanyi's group (and I am not), I don't feel fully confident in fleshing out that article. (I also will not be returning to cwi until Aug 15, and I cannot seem to locate a copy of their book).

Could you be so kind as to take a look at this stub and flesh it out? I took some guesses, and a reference to their book on talk:Invariance theorem. Vonkje 15:12, 23 July 2005 (UTC)

User: stuff in articles...[edit]

If you want to cite your solution in Connect Four, plesae do so in a way that does not refer to User: . The ref to User: is a cross-namespace reference that breaks when the article exported. Fplay 01:08, 12 December 2005 (UTC)


It was hardly a surprise that your link to "Turing Machines" (capital initial "M"; plural) would fail to work. It now works since I created a redirect page. I also changed the link so it said [[Turing machine]]s. That makes it link to the singular (and with lower-case "m"), but the reader sees the whole word, not just the part in brackets, as a clickable link.

I moved the article to binary lambda calculus, with lower-case initials, as required by WP:MOS, and fixed the links to the new redirect page. Michael Hardy (talk) 04:14, 13 March 2009 (UTC)

Connection between Goodstein sequences and Woodall numbers[edit]

Hi Tromp, you added notes ([1] [2]) claiming that all Goodstein sequences after G(4) have length equal to a Woodall number. This is interesting to me, do you have a reference/proof of it? I would be very interested in understanding more. Thanks, — sligocki (talk) 21:07, 14 October 2009 (UTC)


There's no reference as far as I know. I discovered it myself.

For starting numbers of at least 4, the goodstein sequence will at some point reach b^b in hereditary notation. The next step yields b'^b' - 1 which is b * b'^b + b * b'^(b-1) + .... + b, where b' = b+1 is the next base. It's a nice exercise to figure out what will be the final base. You will see how the Woodall number arises.

When you start with 3, the final base of 7 happens to also be a Woodall number, so the property holds for any input >= 3.

regards, -John —Preceding unsigned comment added by Tromp (talkcontribs) 21:05, 20 November 2009 (UTC)


Thanks John, actually, after asking here, I played with them a bit and discovered it myself. It is interesting. Do you know if this connection shows any properties? For example, do you know if there are interesting properties or uses of Woodall numbers that might be used for the Goodstein sequences? Cheers, — sligocki (talk) 02:30, 21 November 2009 (UTC)

Proof-of-work system Cuckoo Cycle : Conflict of interest[edit]

"Cuckoo Cycle" lacks Wikipedia:Verifiability. I've removed it from the list of proofs of work. Furthermore it appears you have a strong Wikipedia:Conflict_of_interest on that subject. Please read and consider both of those articles before adding more content. Thanks, Chris Arnesen 14:54, 27 January 2014 (UTC)

Hi, Chris. Some comments on your undoing of my PoW entry: As to verifiability, my paper has the same status as some other PoWs listed there. Since its original announcement in early January, it has been looked at by many people in the cryptography and cryptocurrency people, including people who designed their own PoWs, and none have found any flaw in it. It has also just been published on the cryptology eprint server at, just like e.g. the Hokkaido PoW listed there. As to conflict of interest, it would be limited to "Citing yourself", which, quoting "is allowed within reason, but only if it is relevant, conforms to the content policies, including WP:SELFPUB, and is not excessive. Citations should be in the third person and should not place undue emphasis on your work." I see you are very interested in bitcoin yourself. You should be able to assess the paper's qualities. Let me know if you find any problems with it. regards, -John — Preceding unsigned comment added by Tromp (talkcontribs) 14:29, 28 January 2014 (UTC)
Welcome to Wikipedia, by the way! We can always use more folks around here who have both in-depth content knowledge and good writing skills, like yourself. The Wikimedia software is pretty deficient when it comes to talk page discussions. I find it's easiest to keep the conversation on one person's talk page (let's use yours). You can alert me to a new comment by adding markup {{ping|Chrisarnesen}} to beginning of your post. It renders like this : @Chrisarnesen:. Also, please sign your posts with four tildes, ~~~~. Conventionally, a comment on a comment is proceeded by an extra colon for indentation. If at some point we get too far indented, you can {{outdent}}────────────────────────────────────────────────────────────────────────────────────────────────────

Anyway, as for verifiability, "Self-published and questionable sources may be used as sources of information about themselves, usually in articles about themselves or their activities". I read that to mean that I could add as a reference to an article about YOU, something YOU had self-published. A self-published reference on the proof-of-work page isn't that thing. As for COI, the last sentence of the paragraph that you quoted from is, "When in doubt, defer to the community's opinion." The Hokkaido reference, like yours, is self-published. Though that citation doesn't properly verify that content, a Google search indicates to me that the content probably is verifiable. (Remove it if I'm wrong). In your case, that doesn't appear to be true yet. Heck the preprint was just posted two days ago. I hope this helps. Cheers, Chris Arnesen 15:05, 28 January 2014 (UTC)