Wikipedia:Featured article candidates/Algebra/archive1

Algebra (edit | talk | history | links | watch | logs)

Nominator(s): Phlsph7 (talk) 08:45, 6 August 2024 (UTC)[reply]

Most people are familiar with algebra from their school days, where they learned to solve equations like  . However, there is also a more abstract form of algebra, which is of particular interest to mathematicians because it provides a general framework for understanding operations on mathematical objects. Thanks to Bilorv for their in-depth GA review and to Mathwriter2718 and Chatul for their peer reviews. Phlsph7 (talk) 08:45, 6 August 2024 (UTC)[reply]

RoySmith (Support)

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  • As an administrative note, I noticed this page had been semi-protected since 2008. 16 years of protection seemed excessive, so I unprotected it.
  • I'm still looking at this, but I do want to say that it's a joy to see a math article which is so approachable. My training is in engineering; I'm a user of math, but not a mathematician. Most math articles (Lie algebra being a good example) make my eyes glaze ever before I get past the first sentence. In this article, I'm down to Linear algebra and I'm still following every detail. This is wonderful!
    Hello RoySmith and thanks for reviewing the article! The parts on abstract and universal algebra will get a little more challenging but this is not entirely avoidable and I hope they are still accessible enough to grasp the main ideas without feeling overwhelmed. Phlsph7 (talk) 15:08, 6 August 2024 (UTC)[reply]
    Yeah, I'm working on Abstract algebra now. Slower going than before, but I'm still hanging in there :-) RoySmith (talk) 15:11, 6 August 2024 (UTC)[reply]
  • The word algebra comes from the Arabic term الجبر (al-jabr), which originally referred to the surgical treatment of bonesetting You can't just leave the reader hanging without giving at least some explanation of how we got from bonesetting to a high-school math class. You link to Traditional bone-setting, but that doesn't say anything about it. I did a bit of searching. "The Origin of the Term "Algebra" on JSTOR". jstor.org. Retrieved 6 August 2024. talks about this a bit while "Simplifying equations in Arabic algebra". sciencedirect.com. Retrieved 6 August 2024. suggests the connection may be entirely accidental. Either way, I think it's worth a sentence or two.
    That's a good idea and the sources are helpful. I put it in a footnote since there is no consensus on the exact meaning. Phlsph7 (talk) 16:01, 6 August 2024 (UTC)[reply]
  • x-y-pair do you need both hyphens? I would think "x-y pair".
    Done. Phlsph7 (talk) 16:07, 6 August 2024 (UTC)[reply]
  • An equation is linear if ... no operations like exponentiation, extraction of roots, and logarithm are applied to variables why the equivocation, i.e. "operations like"? Which operations are like those and which are unlike? My understanding is that an equation is linear if there's no power greater than 1, and things like logs and roots get included in that implicitly via their Taylor series. I think this would be better written as an explicit list of operations that are allowed, rather than a vague "stuff like this isn't allowed".
    Done: I added the general form and cut the "stuff like this isn't allowed" down to a short side remark. Phlsph7 (talk) 16:27, 6 August 2024 (UTC)[reply]
  • An operation[k] is associative if the order of several applications does not matter, i.e., if (a circle b) circle c ... This is the first time you use the circle notation. A little earlier when you introduce N for Natural Numbers, you do a good job of explaining what the notation means; you should do similarly here. My understanding is that it's just "an arbitrary binary operation", but that should be clarified.
    That explanation is given in a footnote, which was unfortunately positioned in a rather unintuitive place. I moved it right after the first use of the circle symbol so that the connection is clearer. Phlsph7 (talk) 08:18, 7 August 2024 (UTC)[reply]
  • An operation admits inverse elements... explain what it means to "admit" an element.
    I reformulated the expression to make it simpler. Phlsph7 (talk) 08:24, 7 August 2024 (UTC)[reply]
  • The natural numbers ... contain only positive numbers Why not "positive integers"?
    Changed. Phlsph7 (talk) 08:24, 7 August 2024 (UTC)[reply]
  • Group theory is the subdiscipline of abstract algebra studying groups. studying -> which studies.
    Reformulated. Phlsph7 (talk) 11:00, 7 August 2024 (UTC)[reply]
  • I'm not sure how File:Magma to group4.svg relates to the rest of the article, or at least to the text it's near. It's near a section that talks about rings and fields, but the diagram only shows relationships for groups. Perhaps it should go with the following paragraph, where magmas et al are discussed?
    You are right, I moved it to the following paragraph. I expanded the caption to make it easier to see how it is relevant to the discussion. Phlsph7 (talk) 11:00, 7 August 2024 (UTC)[reply]
  • They differ from each other in regard to the types of objects they describe and the requirements that their operations fulfill To me, this is the key sentence in this whole section. To go back to my comment about my eyes glazing over when I read articles like Lie algebra, this lays out the logical foundation that helps me read " a Lie algebra (pronounced /liː/ LEE) is a vector space ... together with an operation called the Lie bracket, an alternating bilinear map ... that satisfies the Jacobi identity}} and really start to get my head around what it's saying. By analogy, I have a rudimentary knowledge of Spanish, but I can usually read something well enough to say, "OK, that's a conjugated verb. I don't recognize the verb, and I'm not sure about the tense, but at least I can get past that and keep going with the sentence, knowing I can always go back and look up the verb later". The same thing here. I don't know what an "alternating bilinear map" is, but with your explanation in mind, I can say, "OK, I don't know what that is, but at least I recognize it's describing "the requirements the operation fulfills" and I can keep making progress, knowing I can come back later and dig deeper. The point of this rambling note is just to say that I think this sentence needs more prominent placement, perhaps in the first paragraph of this section. Then you can still conclude the section by saying that you've only described the three most basic structures, and lots of other ones exist, such as magmas, etc.
    I found a way to mention this characterization in the first paragraph. I very much agree with you about the accessibility problems of several math articles. Some of them read as if they were written primarily for mathematicians, which becomes a problem specifically for the lead if an educated non-expert reader can't figure out what the topic of the article is. Phlsph7 (talk) 11:22, 7 August 2024 (UTC)[reply]

(I'm done with Major Branches. I'll pick up with History another day)

I couldn't stay away, so I finished this up today. I really can't find anything else to complain about in the rest of the article. I'll just leave you with a couple of suggestions which you can take or leave at your pleasure. One is that in Other branches of mathematics where you talk about algebraic solutions to geometric problems, you might want to mention that origami has been used to solve algebraic problems using geometry, see for example https://sites.math.washington.edu/~morrow/336_09/papers/Sheri.pdf. The other is that I don't think you can talk about Gerolamo Cardano without at least mentioning that he has been credited with inventing (or at least accepting the existance of) imaginary numbers.

I added a short side remark about origami and mentioned imaginary numbers. Thanks a lot for all the helpful suggestions! Phlsph7 (talk) 12:16, 7 August 2024 (UTC)[reply]
  • I'm not qualified to review this for the quality of the research or comprehensiveness, but I'm happy to give my support for general structure and "prose is engaging and of a professional standard".

Image review

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  • File:Muḥammad_ibn_Mūsā_al-Khwārizmī.png: the fine print on the licensing tag suggests a cropped image like this might not be covered by the copyright exception
    I removed the image since there were also other concerns about it in the comments below. Phlsph7 (talk) 08:39, 7 August 2024 (UTC)[reply]

I know even less about this one than ethics, so a more sensible person would stay away -- a few comments regardless:

  • Linear algebra is a closely related field investigating variables that appear in several linear equations, called a system of linear equations. It tries to discover the values that solve all equations at the same time.: "all equations in the system"? As phrased, it sounds like we mean all equations in existence.
    Good catch. Added. Phlsph7 (talk) 16:56, 7 August 2024 (UTC)[reply]
  • Algebraic methods were first studied in the ancient period: as with ethics, I think we could do with being a little more precise. Are we happy, for instance, that the Rhind papyrus is the earliest document to concern algebra, and/or that none exists older than the 2nd millennium BCE, or that the oldest known studies are from Egypt?
    We could mention the example of the Rhind Papyrus with a date in this lead paragraph. But I'm not sure that we want to go into those details in the lead. Phlsph7 (talk) 15:45, 9 August 2024 (UTC)[reply]
  • A matter of taste, maybe, but I'm not sure about a 1980s postage stamp (especially as the likeness is almost certainly totally fictitious) for al-Khwarizmi, especially if we're not going to tell the reader what the image is (some will, I'm sure, assume it's a contemporary portrait). Elsewhere, we have this, which is a page (I think the first page?) from the text we're discussing -- would that be a better illustration here?
    Good idea, I replaced the image, especially since there were also some copyright concerns above. Phlsph7 (talk) 08:41, 7 August 2024 (UTC)[reply]
  • Transliterated Arabic should be in a transliteration template.
    Done. Phlsph7 (talk) 16:56, 7 August 2024 (UTC)[reply]
  • A higher level of abstraction is achieved in abstract algebra: is is achieved the right phrase here -- it sounds like we're saying that abstract algebra is better than elementary algebra, when surely they're each trying to do slightly different things? "Abstract algebra uses/creates/allows a higher level of abstraction"?
    Reformulated. Phlsph7 (talk) 16:56, 7 August 2024 (UTC)[reply]
  • Suggest linking countable noun.
    Added. Phlsph7 (talk) 16:56, 7 August 2024 (UTC)[reply]
  • Very pedantic, but the link on " a certain type of binary operation" covers the "a", while the one on "a specific type of algebraic structure" doesn't. Usual form is to include it, I think.
    I included the "a" in the wikilink scope. Phlsph7 (talk) 16:56, 7 August 2024 (UTC)[reply]
  • It's a little odd that note c mentions al-Khwarizmi before we've introduced him, and when we're talking about the use of the term prior to his work. I'd move it to the end of the following sentence.
    Done. Phlsph7 (talk) 16:56, 7 August 2024 (UTC)[reply]
  • This changed in the course of the 19th century: why not, simply, in the nineteenth century?
    Simplified. Phlsph7 (talk) 16:56, 7 August 2024 (UTC)[reply]
  • Note e (definition of constants vs. variables) does strictly need a citation, even though it's not exactly controversial. There are a couple of others -- I noticed l and s.
    Done, I hope I got all. I reformulated footnote l to be only about this article. Phlsph7 (talk) 16:56, 7 August 2024 (UTC)[reply]
    I'm not going to kick up a huge fuss on this point, but it would be reassuring to provide a citation to show that other people do this too (in other words, that it's not our own idea). UndercoverClassicist T·C 17:03, 7 August 2024 (UTC)[reply]
    Done. Phlsph7 (talk) 08:01, 8 August 2024 (UTC)[reply]
  • The lowercase letters a and b are usually used for constants and coefficients. For example, the expression 5x+3 is an algebraic expression created by multiplying the number 5 with the variable and adding the number 3 to the result. I don't really understand the use of "for example" here -- I think we need to introduce this as a new thought.
    Done. Phlsph7 (talk) 08:04, 8 August 2024 (UTC)[reply]
  • An equation is a statement formed by comparing two expressions with an equals sign ... Inequations are formed with symbols like the less-than sign (), the greater-than sign (), and the inequality sign (). : would it be better to explain this in terms of meaning rather than symbology? After all, the statement "the square on the hypotenuse is equal to the squares on the other two sides" was as much as passed for an equation for a large part of mathematical history, and we can imagine some other form of notation that expresses equations with a different sign or none at all.
    I reformulated it to take a middle path, covering both meaning and symbols. Phlsph7 (talk) 08:47, 8 August 2024 (UTC)[reply]
  • Some algebraic expressions take the form of statements that relate two expressions to one another: two or more?
    Two is the typical format in algebra. Our formulation leaves it open whether there are other alternatives. Phlsph7 (talk) 08:47, 8 August 2024 (UTC)[reply]
    It does. UndercoverClassicist T·C 14:40, 9 August 2024 (UTC)[reply]
  • The main goal of elementary algebra is to determine for which values a statement is true: more idiomatic, to me, as "the values for which a statement is true".
    Reformulated. Phlsph7 (talk) 08:47, 8 August 2024 (UTC)[reply]
  • In a similar way, if one knows the exact value of one variable one may be able to use it to determine the value of other variables.: do we lose anything important by cutting exact here?
    Not really. Removed. Phlsph7 (talk) 08:47, 8 August 2024 (UTC)[reply]
  • It bothers me that the graph example uses the wrong symbol for subtraction (the dash is too short), but that's not really your problem. Do consider, however, MOS:COLOUR in describing the line as red (not everyone can see its colour) -- perhaps also add that it slopes upwards to the right? I appreciate that there's only one line that graph-literate readers could identify, but we're rightly pitching this article to complete beginners, and it's not impossible that some won't know what the axes are.
    I updated the image file to use a longer symbol for subtraction (I had to close and re-open my browser for it show the new version). I also followed your suggestion to identify the line not only by color but also by slope. Phlsph7 (talk) 08:47, 8 August 2024 (UTC)[reply]
  • This means that no variables are multiplied with each other and no powers of variables occur.: or that no variables are raised to a power greater than one?
    Reformulated. Phlsph7 (talk) 08:47, 8 August 2024 (UTC)[reply]
  • A system of equations that has solutions is called consistent. This is the case if the equations do not contradict each other: better as A system of equations that has solutions is called consistent if the equations do not contradict each other? At the moment, we state something, and then immediately seem to state that it isn't (always) true. If I've got it right, we're saying that it's impossible to be inconsistent and to have any solutions, so it might even be clearer to state that first -- something like If two or more equations contradict each other, the system of equations is called inconsistent and has no solutions. For example, the equations   and   contradict each other since no values of   and   exist that solve both equations at the same time. If two or more equations contradict each other, the system of equations is inconsistent and has no solutions. A system of equations that has solutions is called consistent.
    I implemented a similar reformulation. Phlsph7 (talk) 12:32, 8 August 2024 (UTC)[reply]
  • LU Decomposition: decap decomposition, and consider spelling out lower–upper?
    Decap done. I kept the "LU" since this is the more common way of referring to it and also the name of our article. Phlsph7 (talk) 12:32, 8 August 2024 (UTC)[reply]
  • On a geometric level, systems of equations can be interpreted as geometric figures: do we need the first bit? Seems repetitive, given the end of the sentence.
    Removed. Phlsph7 (talk) 12:32, 8 August 2024 (UTC)[reply]
  • For systems with two variables, each equation represents a line in two-dimensional space. The point where the two lines intersect is the solution: can we briefly explain why this is so?
    I added a short explanation. Phlsph7 (talk) 12:32, 8 August 2024 (UTC)[reply]
  • binary operations, which take two objects as input: as inputs, surely, or as their input?
    Done. Phlsph7 (talk) 12:32, 8 August 2024 (UTC)[reply]
  • The date of the Rhind papyrus -- can we give an idea of the "error bars" on the debate -- does everyone agree it's C17th, for example, or do some people think it's much later, or a modern forgery?
    Done. Phlsph7 (talk) 12:32, 8 August 2024 (UTC)[reply]
  • These developments happened in the ancient period in diverse regions such as Babylonia, Egypt, Greece, China, and India: our phrasing here implies that this list isn't exhaustive. Is that what's intended?
    Simplified. Phlsph7 (talk) 12:32, 8 August 2024 (UTC)[reply]
  • In ancient China: I know the date of The Nine Chapters on the Mathematical Art isn't totally straightforward, but we should give it one anyway, if the Greeks get them.
    Added. Phlsph7 (talk) 12:32, 8 August 2024 (UTC)[reply]
  • On Vector 22, I have quite a lot of sandwiching between the Al-Khwarizmi manuscript and the double portrait. I realise I've earlier suggested using it in place of Al-Khwarizmi's face, so that would solve this problem as well.
    Done. Phlsph7 (talk) 08:42, 7 August 2024 (UTC)[reply]
  • We get a lot of people described as "the nationality mathematician": you could consider dropping mathematician in these contexts, and take it as read that we're generally talking about mathematicians (see User:Caeciliusinhorto/Context considered harmful for an argument for this). Very much a matter of taste, though.
  • the German mathematicians ... Emil Artin -- he was Austrian.
    Done. Phlsph7 (talk) 12:32, 8 August 2024 (UTC)[reply]
  • to solve puzzles like Sudoku and Rubik's cube: we generally speak of a Rubik's cube, so I'd pluralise it here (especially as there are different variations on the form).
    Done. Phlsph7 (talk) 12:32, 8 August 2024 (UTC)[reply]
  • Algebra education mostly focuses on elementary algebra, which is one of the reasons why it is also called school algebra. It is usually not introduced -- the series of its may not be totally clear -- we seem to be swapping antecedent here (the first one is elementary algebra, the second algebra education).
    I replaced the first "it". Phlsph7 (talk) 12:32, 8 August 2024 (UTC)[reply]
  • unlike arithmetic calculations, algebraic expressions often cannot be directly solved: you might add an easily in here -- you can solve most school problems by trial and error, or simply by spotting the answer, but it's much easier to do it "properly".
    I guess it depends on whether we read "often cannot" as "in many cases, there is no logical possibility" or as "in many cases, there is no reliable way to do so". I would add it but "easily directly solved" sounds a bit odd. Phlsph7 (talk) 12:32, 8 August 2024 (UTC)[reply]
    To me, often cannot easily be directly solved is good English -- or perhaps "are often difficult to solve directly"? UndercoverClassicist T·C 14:06, 8 August 2024 (UTC)[reply]
    Done. Phlsph7 (talk) 16:03, 8 August 2024 (UTC)[reply]
  • On the education side -- how worldwide is the use of balance scales? We've cited a single school textbook here, which to me is verging on WP:PRIMARY -- I'd be more comfortable with a survey article on the use of the technique in (American?) mathematical education. I've never seen it in UK schools, outside isolated word problems -- function machines are more common over here as a basic introduction to the ideas of algebra. I'd be interested to know how things are done in places like Shanghai and Hong Kong, which generally seem to outperform both systems, at least as far as concerns producing students who can solve school-algebra problems.
    I added two more sources that that examine some research on this approach. Phlsph7 (talk) 12:32, 8 August 2024 (UTC)[reply]
    Both of these sources (particularly Kaput 2018) consider balance scales as one tool among many -- Kieran talks about other manipulatives (cups and sticks, for example), and Kaput talks about a whole bunch of visualisations (including function machines), particularly those which they feel to be appropriate for use with a computer. I think the discussion here needs to be broadened to reflect those sources -- there's a good point to be made that teaching algebra often involves using conceptual tools, often ones with which students can interact physically, before introducing abstract concepts such as variables, but we shouldn't frame that entirely through one of those tools (balance scales). There's an interesting booklet for teachers here, with extensive bibliography, which recommends the use of representations but also acknowledges that the evidence for their effectiveness (like everything else in education!) is minimal. UndercoverClassicist T·C 14:13, 8 August 2024 (UTC)[reply]
    I added some additional context to the discussion by mentioning manipulatives and visualizations. Phlsph7 (talk) 15:41, 9 August 2024 (UTC)[reply]
    I've made a small and slightly pedantic fix (computers aren't visualisations), but I think this works well now. Feel free to counter-tweak. UndercoverClassicist T·C 16:37, 9 August 2024 (UTC)[reply]
    Looks good. Phlsph7 (talk) 16:48, 9 August 2024 (UTC)[reply]

Can I echo Roy's praise for the clarity and approachability of this article -- I'll admit that I skipped fairly lightly over the abstract algebra section, but the rest was absolutely clear and manageable, and I suspect I'm going to be one of the least qualified mathematicians to review this here. Excellent work once again. UndercoverClassicist T·C 06:55, 7 August 2024 (UTC)[reply]

Thanks for yet another detailed review and for taking a leap to provide a non-expert opinion on the article! Given that Wikipedia is a general encyclopedia, this is also an important perspective to consider. Phlsph7 (talk) 08:55, 7 August 2024 (UTC)[reply]
Support: I am hugely impressed by the writing and clarity here, and while I am not qualified to vouch for the mathematics, everything within my expertise looks excellent. UndercoverClassicist T·C 16:38, 9 August 2024 (UTC)[reply]
Thank you for the support! Phlsph7 (talk) 08:39, 10 August 2024 (UTC)[reply]

Comments Edwininlondon

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Although I am neither an expert in the field nor a native speaker, I have a few comments. Overall I very much appreciated the clarity and structure.

  • Algebra is the branch of mathematics that studies algebraic structures --> while I like overall how clearly topics are being described, there are a few cases where I get a sense of recursion. Is there a way to avoid using algebraic in the definition of algebra?
    You are right that this sounds circular, but I'm not sure that there is a good alternative. There was already a detailed discussion on this point in the GA review that resulted in consensus on the current formulation. It sounds circular but it isn't circular since the technical term "algebraic structure" is defined without reference to algebra. Phlsph7 (talk) 16:05, 9 August 2024 (UTC)[reply]
  • called a system of linear equations. --> why italics?
    This is per MOS:WORDSASWORDS since we talk about the term "system of linear equations". Phlsph7 (talk) 16:05, 9 August 2024 (UTC)[reply]
  • that appear in several linear equations --> a definition of linear would be good
    We could add a footnote but I'm not sure that we should get into this in the lead section. The first paragraph of the subsection "Linear algebra" provides a definition. Phlsph7 (talk) 16:05, 9 August 2024 (UTC)[reply]
  • Algebra is the branch of mathematics that studies algebraic operations[a] and algebraic structures --> too recursive for me. A question: do I understand it correctly that algebraic structures include lgebraic operations? If so, do we really need to say "algebraic operations[a] and algebraic structures" or can it just use structures?
    You are right, the operations are already included. I found a way to reformulate the sentence to take this into account while cutting down on the repetitive language. Phlsph7 (talk) 16:05, 9 August 2024 (UTC)[reply]
  • Arithmetic studies arithmetic operations --> too recursive for me
    I removed the term "arithmetic" since we already list the main operations. Phlsph7 (talk) 16:05, 9 August 2024 (UTC)[reply]
  • first use of axiom in body is not linked. Perhaps do this: together with their underlying axioms, the laws they follow.
    Done. Phlsph7 (talk) 16:05, 9 August 2024 (UTC)[reply]
  • The natural numbers, by contrast, do not form a group --> should the + operation not be mentioned?
    Correct, I added it. Phlsph7 (talk) 16:35, 9 August 2024 (UTC)[reply]
  • One of the earliest documents is the Rhind Papyrus --> One of the earliest mathematical documents is the Rhind Papyrus
    I implemented the idea in a slightly different way. Phlsph7 (talk) 16:35, 9 August 2024 (UTC)[reply]
  • several generations between the 10th century BCE and the 2nd century CE --> I don't think 1000+ years can be described as several generations
    Agreed, this is an understatement. I adjusted the text. Phlsph7 (talk) 16:35, 9 August 2024 (UTC)[reply]
  • Thābit ibn Qurra in the 9th century --> I assume there is no more accurate estimate? Since 825 CE is also the 9th century, perhaps something like "also in the 9th century"?
    I think he made contributions in several works so we would have to list several dates. I added the "also". Phlsph7 (talk) 16:35, 9 August 2024 (UTC)[reply]
  • In 1247, the Chinese mathematician Qin Jiushao --> how come this is not with the other China info?
    For chronological reasons: roughly speaking, we have two paragraphs on ancient history, two paragraphs on post-classical history, and then modern history. It's not ideal but putting him into the ancient paragraph is not ideal either. Phlsph7 (talk) 16:35, 9 August 2024 (UTC)[reply]

That's all I could see. Nice work. Edwininlondon (talk) 19:50, 8 August 2024 (UTC)[reply]

Hello Edwininlondon, I appreciate you taking the time to review this article! Phlsph7 (talk) 16:05, 9 August 2024 (UTC)[reply]

A bit more:

  • x y c – variables/constants --> would be better to make 2 lines and separate the variables from the constant
    Done. Phlsph7 (talk) 11:12, 12 August 2024 (UTC)[reply]
  • forgive me if this has been agreed already, but is Encyclopedia of Mathematics as a wiki a reliable source?
    Thanks for raising this point. The website use wiki software to display the pages but it is not user-generated. The articles were originally published in book form by Kluwer Academic Publishers/Springer and only later made accessible online. We could cite the original books but the online version is much better accessible for readers. Phlsph7 (talk) 11:12, 12 August 2024 (UTC)[reply]
  • inconsistent date formats. Example: "from the original on 4 October 2009. Retrieved 23 October 2023" but also "from the original on 2024-01-12. Retrieved 2024-01-13"
    Done. I hope the script got all. Phlsph7 (talk) 11:41, 12 August 2024 (UTC)[reply]
  • Walz, Guido (2016) needs a trans-title
    Added. Phlsph7 (talk) 11:41, 12 August 2024 (UTC)[reply]
  • Spotcheck: 37 51 84 85 87 118 all check out
  • 80 does indeed give 1550 but somehow I feel this source is not right to make the claim "The exact date is disputed and some historians suggest a later date around 1550 BCE" A more scientific source would be better.
    I replaced it with a better source. Phlsph7 (talk) 11:41, 12 August 2024 (UTC)[reply]
  • 87 is correct but the link unfortunately does not put me on page 31, nor is that page accessible to me. Perhaps this link is better: https://nap.nationalacademies.org/read/11540/chapter/4
    I fixed the link, the page preview works for me now. Phlsph7 (talk) 11:41, 12 August 2024 (UTC)[reply]

That's it for this final round. Edwininlondon (talk) 07:16, 11 August 2024 (UTC)[reply]

Thanks for your comments. I hope I was able to address the main concerns. Phlsph7 (talk) 11:41, 12 August 2024 (UTC)[reply]