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Talk:Ordinal number

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803:, would be in scope for articles on order theory, or (in that context) as a construction of the integers from the natural numbers, as ordered sets. It's out of scope for ordinals since the structures it produces are not regarded as ordinals (in mathematics, which is where he proposed it, right?) and nobody adopted Russell's idea of calling these things "negative ordinals". Russell misapplied or misunderstood the term "negative" here; the point in mathematics is to create a group from a semigroup, not a minus sign as a reverse direction. 436: 426: 405: 372: 859:
constructing integers from positive integers is create a homogeneous structure (transitive symmetry group), not an artificial left-right symmetry put in by hand by creating a duplicate mirrored copy. Russell's construction does not really sew the left and right sides together properly, in that whether you have unique successor or unique predecessor depends on which half you are in; it's not a single structure working differently than the sum of its parts.
251: 515: 1149:. As for 1.: oops, sorry! As for 2.: I now darkened the colors from RGB (100%,0%,0%) for red (similar for green, blue) and (80%,80%,0%) for yellow (similar for cyan, magenta) to (80%,0%,0%) and (50%,50%,0%). I find the result still hard to read. On the other hand, I'd like to keep the "rainbow" effect which makes it easier to recognize which label belongs to which spiral turn. Moreover, inspired by the current image 219: 363: 996:
until it reaches the center which would be ω. The spoke beginning with 1 would continue with ω·2, ω·2 ω·2, etc.. Between these, new spokes should begin in the second turn, ω+1 would continue with ω+ω. Clearly, most of these numbers would have to be replaced with just tick-marks and as you proceed around the spiral, and most of those would have to be omitted altogether.
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After recently looking at the Ordinal number article, I see that you changed the black and white picture to a color one (March of last year). Is that really an improvement? The old version seemed a lot easier to look at. The new layout is good, but the lack of contrast with the washed-out tones of
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The outermost ring of the spiral should begin with 0 at the 12:00 high position and continue with the natural numbers coming closer together until the first turn is completed. At that point it should meet ω which should be directly under 0. The spoke beginning with 0 would continue with ω, ω, ω, etc.
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In over a century, this definition of Russell's never caught on. You can "double" any linear (or partial) order that has a minimum element, putting in a reflection symmetry by fiat, but what does that accomplish? Apparently not much, since Russell's terminology did not gain acceptance. The gain in
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I think, each stick denotes one number, so the sticks at the left end denote the numbers 0, 1, 2, 3, 4, ... . The leftmost "completely black triangle" (appearance to the human eye) then has ω at its tip. The next sticks right to it denote ω+1, ω+2, ω+3, ω+4, ... . The rightmost end of the picture
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Hmm, I suppose we could have a brief mention of the surreals (if we don't already; haven't checked) but the Russell thing is kind of anachronistic for that, maybe a precursor but not using terminology that has survived (come to think of it, you could say that about much of Russell's work in math
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It's probably my own confusion, but the caption makes little sense to me. Assuming a "matchstick" is a single vertical line, shouldn't the caption read "... ω^3 . Each stick corresponds to ... ω."  ? In any event, isn't the "+n" in the quoted caption useless?
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I am no expert, to be sure, on ordinals but can we please finally dump these attempts at graphical representations? the 'spiral' and 'matchstick' images -- they add nothing to the explanation and as far as I can see are not even discussed in the article text.
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There are not, in fact, "negative ordinals", not in the sense intended in this article. This article is about a specific structure in set theory, which has no negative ordinals. Just because a reliable source uses the same
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The images are intended to illustrate the structure of (initial segments of) the ordinal numbers. The spiral form is just a hack to avoid an extreme aspect ratio. Do you have suggestion about alternatives? -
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It seems that the Svg file can be edited with an ordinary text editor, so I can offer to change the labels according to your suggestions. However, I'm afraid I didn't understand them. It seems that after
711:, and naturally with scientific notation there are negative Ns. Thus it seems necessary to acknowledge negative ordinals to properly document these order of magnitude articles in that category. — 1207: 492: 879:
There is an image with the caption "A graphical "matchstick" representation of the ordinal ω². Each stick corresponds to an ordinal of the form ω·m+n where m and n are natural numbers."
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for comparison purposes. The colors are intended to ease distinguishing the different turns of the spiral and to ease recognition of which label belongs to which spoke.
1123:; the latter is unusual in my experience and the 2 looks like it could be a misplaced superscript or subscript. I agree about the yellow; that's pretty hard to see. -- 1398: 1413: 376: 1423: 482: 79: 778:
of this article? So what that the transfinite ordinals are the "interesting ones", the encyclopedia is to serve all readers, young and old. The article
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logic). It's not really even clear from the excerpt given just what Russell was talking about -- does anyone have it handy to give more context? --
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Should we disregard one old source by Russell or thousands of more recent articles which use "ordinal" in a sense which excludes negatives?
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At least the latter fact is worth mentioning in the article; and why not give Russell's reference (but not the full quotation) then, too? -
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is the best of the three. The colors make it easier to distinguish the turns, and it's also easier to read without the fade-out effect.
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Bertrand Russell wrote his book in response to continental developements in logic and set theory. How dare editors remove the on-topic
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The "negative fourth magnitude" has no apparent connection to the topic of this article. It might have some connection with the
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is your focus, but the general reader needs to know that there are negative ordinals, especially for the reason given above. —
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I started to redesign the picture according to your suggestion; it will take a few days to get the limit ordinals arranged. -
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was reverted as "surreal"! Now an illustration, as Venus has negative fourth apparent magnitude, is appended. Any comments? —
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then denotes ω^2. Maybe, the phrase "matchstick representation" should be explained in a footnote (along the above lines). -
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It took me longer than expected, but now I came up with a first version that meets the above requirements (I hope), see
385: 574: 65: 755:. The interesting ones are infinite; finite ordinals are not in any essential way different from natural numbers. -- 1156: 1326: 1214: 1037: 1015: 986: 941: 904: 675: 638: 218: 185: 250: 1241:
I think you put the wrong link. We don't want a PDF as an image (not sure that even works). Probably you meant
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nearly all the uses refer to a heirachial organization where N corresponds to an ordinal number such as at
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corresponds to one turn of the spiral. If I could, I would change it so that that function is α -: -->
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for which your comments might make a certain amount of sense; that sense is discussed at our article
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on Knowledge. If you would like to participate, please visit the project page, where you can join
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the colors makes the whole thing hard to follow and understand what is going on. Any thoughts?
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a x 10 there is some discussion concerning the label for N beyond mere exponent. Some usage of
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I also have uploaded a version using the (darker) spoke colors for label coloring, too, see
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https://upload.wikimedia.org/wikipedia/commons/a/af/Omega-exp-omega-normal-dark_svg.svg
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2. Please use darker colors. Yellow on white is virtually illegible (to me at least).
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The matchsticks are good. They clearly show how ω can be embedded into the reals.
745:, not here. That's fundamentally a linguistic rather than mathematical concept. 454: 431: 557: 233: 1348: 1330: 1305: 1291: 1268: 1254: 1236: 1218: 1132: 1069: 1041: 1019: 1005: 990: 967: 945: 929: 908: 892: 868: 851: 837: 812: 791: 764: 720: 679: 657: 642: 628: 602: 977:
turns, we are at ω; but I'm not sure whether your α corresponds to my
619:, which embed a copy of the ordinals, and which have negatives.) -- 800: 707:. A number of these orders of magnitude have been assembled in a 1259:
No, Trovatore. That is not it. That is an old incorrect version.
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are you sure you've understood what this article is actually
271:. Once these issues have been addressed, the article can be 1321:; it has a reduced fade-out effect; I' prefer this one. - 737:? I grant you that there's a different sense of the term 958:ω·(1 + α). However, I do not know how to edit the image. 699:
has been noted but also that at the disambiguation page
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The spiral could be improved by defining clearly what
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should replace what is in the article. Thanks again.
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of the decision if they believe there was a mistake.
751:article is about the ordinal numbers introduced by 1201: 1115: 1092: 824:does not imply that it's talking about the same 615:(The "surreal" comment is probably a pun on the 33:for general discussion of the article's subject. 1409:Knowledge level-5 vital articles in Mathematics 1202:{\displaystyle \omega ,\omega +1,...,\omega +4} 828:, or that it is on-topic for this article. -- 799:Russell's construction, in the generality of 568:This page has archives. Sections older than 174: 8: 1296:Yes, please turn off the fade-out effect. 1153:, I'd added some fade-out effect, e.g. at 399: 286: 245: 1158: 1105: 1079: 1046:Thank you for your effort. Two problems: 1319:File:Omega-exp-omega-normal-dark svg.svg 1399:Knowledge vital articles in Mathematics 401: 360: 1312:File:Omega-exp-omega-normal-bw svg.svg 578:when more than 5 sections are present. 1414:B-Class vital articles in Mathematics 7: 915:Get rid of pictures, or replace them 447:This article is within the scope of 1026:File:Omega-exp-omega-normal svg.svg 390:It is of interest to the following 23:for discussing improvements to the 1424:High-priority mathematics articles 670:under "See also") is just fine. - 14: 572:may be automatically archived by 467:Knowledge:WikiProject Mathematics 1394:Knowledge level-5 vital articles 1243:File:Omega-exp-omega-labeled.svg 1151:File:Omega-exp-omega-labeled.svg 1140: 513: 470:Template:WikiProject Mathematics 434: 424: 403: 370: 361: 249: 217: 45:Click here to start a new topic. 1310:I've uploaded a b/w version at 1225:File:Omega-exp-omega-normal.pdf 1030:File:Omega-exp-omega-normal.pdf 487:This article has been rated as 1404:B-Class level-5 vital articles 1093:{\displaystyle \omega \cdot 2} 1032:. Comments are appreciated. - 909:20:41, 21 September 2021 (UTC) 893:00:23, 20 September 2021 (UTC) 1: 1269:14:48, 10 February 2023 (UTC) 1255:01:52, 10 February 2023 (UTC) 991:13:12, 31 December 2022 (UTC) 968:00:35, 31 December 2022 (UTC) 946:19:07, 30 December 2022 (UTC) 930:13:20, 30 December 2022 (UTC) 869:06:10, 29 November 2020 (UTC) 852:06:04, 29 November 2020 (UTC) 838:05:56, 29 November 2020 (UTC) 813:06:31, 29 November 2020 (UTC) 792:04:32, 29 November 2020 (UTC) 765:04:33, 28 November 2020 (UTC) 721:01:35, 28 November 2020 (UTC) 680:19:26, 27 November 2020 (UTC) 658:19:09, 27 November 2020 (UTC) 643:10:00, 27 November 2020 (UTC) 629:04:01, 27 November 2020 (UTC) 603:03:26, 27 November 2020 (UTC) 589:A section quoting Russell in 461:and see a list of open tasks. 42:Put new text under old text. 1419:B-Class mathematics articles 1237:19:46, 9 February 2023 (UTC) 1219:12:08, 9 February 2023 (UTC) 1209:; should I turn that off? - 1133:01:44, 9 February 2023 (UTC) 1070:01:00, 9 February 2023 (UTC) 1042:18:14, 8 February 2023 (UTC) 1020:17:19, 23 January 2023 (UTC) 875:Faulty caption on pictorial? 774:? Why are negative ordinals 1057:ω. 2ω = ω < ω + ω = ω2 . 1006:00:05, 1 January 2023 (UTC) 50:New to Knowledge? Welcome! 1440: 691:By way of explanation: In 275:. Editors may also seek a 591:Principles of Mathematics 486: 419: 398: 347: 334:Good article reassessment 289: 285: 263:Mathematics good articles 80:Be welcoming to newcomers 1349:18:18, 22 May 2024 (UTC) 1331:07:51, 19 May 2024 (UTC) 1306:04:55, 15 May 2024 (UTC) 1292:04:49, 15 May 2024 (UTC) 1116:{\displaystyle \omega 2} 493:project's priority scale 450:WikiProject Mathematics 1389:B-Class vital articles 1384:Delisted good articles 1203: 1117: 1094: 666:' recent edit (adding 575:Lowercase sigmabot III 75:avoid personal attacks 1204: 1118: 1095: 377:level-5 vital article 350:Delisted good article 269:good article criteria 211:Auto-archiving period 100:Neutral point of view 1157: 1104: 1078: 662:Ok, I see. 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