[HN Gopher] Graduate Student's Side Project Proves Prime Number ...
       ___________________________________________________________________
        
       Graduate Student's Side Project Proves Prime Number Conjecture
        
       Author : theafh
       Score  : 351 points
       Date   : 2022-06-06 13:40 UTC (9 hours ago)
        
 (HTM) web link (www.quantamagazine.org)
 (TXT) w3m dump (www.quantamagazine.org)
        
       | vishnugupta wrote:
       | This brings back memories to me. Almost exactly 2 decades ago a
       | related theorem, prime factorisation being in P, was proved by a
       | couple of undergrads working with a professor in IIT Kanpur,
       | India [1]. The story and the sensation it caused is still fresh
       | in my memory because I had just begun my post-graduation studies
       | in another IIT (IIT Bombay). There was sort of a festival
       | atmosphere in the campus; with all sorts of seminars arranged,
       | discussion groups and what not.
       | 
       | To this day I have not tried to understand the paper; just that
       | it was hailed as one of the shortest and most elegant proofs.
       | 
       | [1] https://frontline.thehindu.com/other/article30245904.ece
       | 
       | [1] https://frontline.thehindu.com/other/article30245904.ece
        
         | q-big wrote:
         | > Almost exactly 2 decades ago a related theorem, prime
         | factorisation being in P, was proved by a couple of undergrads
         | working with a professor in IIT Kanpur, India
         | 
         | It is still an open problem whether prime factorization is in P
         | or not. What Manindra Agrawal, Neeraj Kayal and Nitin Saxena
         | showed is that _checking_ whether a given (binary) number is
         | prime is in P. Up to today, no polynomial-time method has been
         | published to obtain a non-trivial factor of the input if the
         | AKS algorithm returns that it is not prime.
        
           | vishnugupta wrote:
           | Oops; you are right. If my memory serves right, showing prime
           | factorisation in P will imply P == NP; which would have been
           | a sensational news at a different level altogether.
        
             | Ar-Curunir wrote:
             | No, factoring being in P would not imply P == NP. Factoring
             | is not NP-hard.
        
               | Laakeri wrote:
               | Well, it is also not proved to not be NP-hard, so it
               | could also be NP-hard to our current knowledge. But you
               | are right that researchers believe that it's not NP-hard.
        
             | q-big wrote:
             | > showing prime factorisation in P will imply P == NP
             | 
             | Whether "Factorization is in P" actually implies "P=NP" is
             | another open problem (most researchers in this area don't
             | believe that this is the case).
             | 
             | What does hold is that if we found a "fast" algorithm for
             | factorization, this would break some cryptosystems. The
             | most well-known example is RSA, but other, more academic
             | cryptosystems would be broken, too.
             | 
             | In its "Public key cryptography" template (https://en.wikip
             | edia.org/wiki/Template:Cryptography_public-k... click
             | "[show]"), Wikipedia lists the following cryptosystems to
             | be dependent on the hardness of integer factorization:
             | * Benaloh       * Blum-Goldwasser       * Cayley-Purser
             | * Damgard-Jurik       * GMR       * Goldwasser-Micali
             | * Naccache-Stern       * Paillier       * Rabin       * RSA
             | * Okamoto-Uchiyama       * Schmidt-Samoa
        
       | scrubs wrote:
       | >>Erdos found that for any primitive set, including infinite
       | ones, that sum -- the "Erdos sum" -- is always finite. No matter
       | what a primitive set might look like, its Erdos sum will always
       | be less than or equal to some number. And so while that sum
       | "looks, at least on the face of it, completely alien and vague,"
       | Lichtman said, it's in some ways "controlling some of the chaos
       | of primitive sets," making it the right measuring stick to use.
       | 
       | Finite? Surely there must be an operation done to each element of
       | the set before summing to achieve a finite bound.
        
         | alanh wrote:
         | Upvoting because this post shouldn't have a negative score
         | simply for being confused. Treating it as a reasonable
         | question.
        
         | yunwal wrote:
         | The paragraph directly before the one you quoted explains the
         | sum:
         | 
         | > For every number n in the set, plug it into the expression
         | 1/(n log n), then add up all the results. The size of the set
         | {2, 3, 55}, for instance, becomes 1/(2 log 2) + 1/(3 log 3) +
         | 1/(55 log 55).
        
         | S4M wrote:
         | It said that the quantity sum(1/(n log n) for n in A) is always
         | finite when A is a primitive set. The "operation done to each
         | element of the set" is n -> 1 / (n log n).
        
         | Enginerrrd wrote:
         | > "For example, rather than counting how many numbers are in a
         | set, they might do the following: For every number n in the
         | set, plug it into the expression 1/(n log n), then add up all
         | the results. The size of the set {2, 3, 55}, for instance,
         | becomes 1/(2 log 2) + 1/(3 log 3) + 1/(55 log 55).
         | 
         | Erdos found that for any primitive set, including infinite
         | ones, that sum -- the "Erdos sum" -- is always finite."
         | 
         | Read the paragraph just above it.
        
       | adenozine wrote:
       | THIS ONE is definitely the worst HN title gore I've seen so far.
       | Jesus, I nearly choked on my bagel.
        
         | oh_my_goodness wrote:
         | The title's fine.
        
       | tomp wrote:
       | What a crap article.
       | 
       | > Typically, you might associate to it all multiples of 618 whose
       | smallest prime factor is 103.
       | 
       | There are _no_ multiples like that. _All_ multiples of 618 (= 2 *
       | 3 * 103) have 2as the smallest prime factor.
       | 
       | Did anyone figure out what they _actually_ wanted to say?!
        
         | coliveira wrote:
         | Of course there is at least one such multiple: 103 * 618.
        
           | Twisol wrote:
           | > Of course there is at least one such multiple: 103 * 618.
           | 
           | 103 * 618 is divisible by 2, which is a prime strictly
           | smaller than 103. Every multiple of 618 is divisible by 618,
           | and so is _also_ divisible by anything that divides 618.
           | 
           | A cousin comment clarifies that, for x * 618, we're
           | interested in the divisors of x, not x * 618. The article,
           | however, is at best ambiguous in its language; you'd have to
           | interpret the term "multiple" as meaning the multiplier
           | applied to the base number, not the result of said
           | multiplication. The latter is what is usually understood.
        
         | jwilk wrote:
         | They make the same mistake earlier on:
         | 
         | > And associated to the number 55 (5 x 11) would be all
         | multiples of 55 whose smallest prime factor is 11 (therefore
         | excluding all multiples of 2, 3, 5 and 7).
        
         | [deleted]
        
         | [deleted]
        
         | kens wrote:
         | The tan box in the article explains this set. The multiples are
         | nx618 where the smallest prime factor of _n_ (not of nx618) is
         | >=103 (if any). I.e. 618, 103x618, 107x618, 109x618, etc.
        
           | tomp wrote:
           | No, the tan box is similarly non-sensical and the example is
           | 3 primes so it doesn't explain it either.
           | 
           | Your explanation is clear though, thanks!
        
         | williamscales wrote:
         | > Did anyone figure out what they actually wanted to say?!
         | 
         | Did you read the paper?
        
           | thaumasiotes wrote:
           | You would generally hope that the popular coverage of the
           | paper would
           | 
           | (1) avoid making statements that are obviously nonsense, such
           | as "And associated to the number 55 (5 x 11) would be all
           | multiples of 55 whose smallest prime factor is 11"; and
           | 
           | (2) not require reading the paper itself in order to
           | interpret the popular coverage.
           | 
           | If you're going to read the paper, why would you read someone
           | else's paper-inspired gibberish? What value does that add?
        
       | ashton314 wrote:
       | So, does he just get to walk away with a PhD for this?
        
         | Olphs wrote:
         | Well he worked on it for 4 years (for fun?), so I'm not sure
         | what you mean by walk away with a PhD. To me it seems like he
         | has earned it, and even if he doesn't get one he obviously is
         | able to
        
           | scrumbledober wrote:
           | I think he is implying that this is such an accomplishment
           | that the rest of the process of getting a PhD should just be
           | waived.
        
             | t_mann wrote:
             | In this specific case the guy has 16 other published papers
             | already, so if he'd wanted to walk away with a PhD he
             | probably could easily have done so already. That being
             | said, I'd imagine that Oxford would be one of the places
             | that could find a way to award a PhD for genuinely
             | outstanding but unusually short work if that had been his
             | only achievement and he'd asked for it. Seems like one of
             | the few universities still run chiefly by academics, not
             | administrators.
        
             | tantalor wrote:
             | That would defeat the purpose of the process.
        
               | ryanianian wrote:
               | > That would defeat the purpose of the process.
               | 
               | On the contrary, this is the exception that proves the
               | rule. The process exists because we can't expect once-in-
               | a-lifetime works to appear from every candidate.
        
               | alisonkisk wrote:
               | How so? The "process" of getting PhD is writing up his
               | proof and getting it reviewed by the university, and
               | verifying via oral defense that he knows the proof and
               | didn't just plagiarize it.
        
               | pknomad wrote:
               | I think there's a precedence for it too. I believe George
               | Dantzig's doctoral advisor offered to accept the
               | solutions to a homework set as a thesis since it solved
               | major open statistical problems.
        
               | anonymousisme wrote:
               | For those who don't know, here's some background on
               | Dantzig:
               | 
               | "During his first year as a doctoral student at the
               | University of California-Berkeley, Dantzig arrived late
               | to the class of Jerzy Neyman, one of the great founders
               | of modern statistics. On the blackboard were two problems
               | that Dantzig assumed to be homework.
               | 
               | "A few days later I apologized to Neyman for taking so
               | long to do the homework--the problems seemed harder to do
               | than usual," Dantzig once recalled. It turned out the
               | conundrums, which Dantzig solved, were two famous
               | unsolved problems in statistics."
               | 
               | https://news.stanford.edu/news/2005/may25/dantzigobit-052
               | 505...
        
       | mjfl wrote:
       | I can't even get my main project to work...
        
       | phkahler wrote:
       | >> In 2019, he and Carl Pomerance, his adviser at Dartmouth --
       | who, according to Lola Thompson, a mathematician at Utrecht
       | University and a former student of Pomerance, essentially "came
       | out of retirement to work with him"
       | 
       | Somehow that made this whole story a lot more human to me.
       | Pomerance is a big name in modern number theory (to me anyway)
       | but apparently at the end of the day he's just another guy with a
       | particular set of interests who will pop up again when the right
       | thing comes his way.
        
         | ashton314 wrote:
         | For those who don't know, Carl Pomerance was the guy who came
         | up with/discovered the quadratic field sieve which for a time
         | was the fastest factoring algorithm for large (100-ish digits)
         | semiprimes. He has a beautiful write-up describing the
         | algorithm and the story of its discovery:
         | 
         | Pomerance, Carl. "A Tale of Two Sieves." In Biscuits of Number
         | Theory, edited by Arthur Benjamin and Ezra Brown, 85-104.
         | Providence, Rhode Island: American Mathematical Society, 2009.
         | https://doi.org/10.1090/dol/034/15.
        
       | mg wrote:
       | I like to put things on x/y-charts to get a visual overview. Even
       | things that usually are not displayed in this fashion.
       | 
       | When it comes to prime numbers, it always irked me, that one
       | cannot easily look at them in a visual way. I always thought that
       | they would probably look beautiful.
       | 
       | One day, I had the idea to counter this by visualizing prime
       | numbers in the complex plane. I then wrote a little script to
       | colorize each number in the complex plane by how "prime" it is.
       | And indeed, the result looks beautiful:
       | 
       | https://www.gibney.org/does_anybody_know_this_fractal
       | 
       | Then I went back to do more mundane things with x/y charts. The
       | one that became most popular is Product Chart:
       | 
       | https://www.productchart.com
       | 
       | But every once in a while, I still dream about the "complex
       | divisor fractal" and what mysteries might be hidden inside of it.
        
         | frogperson wrote:
         | There are many visualizations of the primes in 2D and many are
         | fascinating. I've always wondered what it would look like in 3d
         | or 4d or higher. what if the primes were mapped on to some
         | crazy topological shape? Is there some shape and dimension out
         | there that produces a "perfect" pattern?
        
         | coldtea wrote:
         | > _When it comes to prime numbers, it always irked me, that one
         | cannot easily look at them in a visual way. I always thought
         | that they would probably look beautiful._
         | 
         | There are several of visualizations of prime numbers, and they
         | do, look beautiful.
         | 
         | E.g.:
         | 
         | https://jaketae.github.io/study/prime-spirals/
         | 
         | https://www.cantorsparadise.com/unexpected-beauty-in-primes-...
         | 
         | https://mathworld.wolfram.com/PrimeSpiral.html
        
         | CapmCrackaWaka wrote:
         | I have seen many "plots" of prime numbers that look really
         | good. In addition to looking good, I sometimes _swear_ I see a
         | pattern. It's really frustrating, to see something on a graph
         | which looks like it follows some pattern or algorithm[1], and
         | to know that finding the mathematical definition of that
         | pattern would would be revolutionary, world news. I can see why
         | so many people get sucked into this problem.
         | 
         | [1]
         | https://www.reddit.com/r/math/comments/7v02i6/comparison_bet...
        
           | mg wrote:
           | There is a movie from 1998 called "pi" about a number
           | theorist who got sucked into it:
           | 
           | https://en.wikipedia.org/wiki/Pi_(film)
           | 
           | I saw it a long time ago, but still vividly remember some of
           | the scenes.
        
           | CyborgCabbage wrote:
           | Knew I remembered that spiral from somewhere
           | https://www.youtube.com/watch?v=EK32jo7i5LQ
        
             | hinkley wrote:
             | This is a very good video.
             | 
             | The tl;dr on it is that all primes are of the pattern
             | 3n+-1, and 2 (polar coordinates) is .283 mod 3, hence the
             | primary curve. Then he explains about fractions that
             | approximate pi, but I think he's over-explaining. Reducing
             | a fraction means making the denominator and numerator co-
             | prime, and in the case of pi approximations, the
             | interesting ones all have prime numbers as the denominator,
             | so the 3n+-1 pattern appears again.
        
         | mananaysiempre wrote:
         | You have seen the Ulam spiral[1] from 1963, right? I don't know
         | that it provides any actual insight into this stupenduously
         | complicated[2] topic, but if you want something to draw about
         | prime numbers that's probably the best-known option. Or see the
         | story about "primons"[3] for a view that's less visual but no
         | less tangible (given a certain kind of background at least).
         | 
         | And yes, as you note, your CDF very much looks like a square
         | grid after an inversion. That is to say: draw a square grid on
         | a horizontal plane, lay down a ball on that plane, project the
         | image onto the surface of the ball by straight rays through its
         | topmost point (imagine a lightbulb there; see? "projection"),
         | then take a parallel plane touching that same ball and project
         | back onto it from the surface (now casting rays from the
         | bottommost point).
         | 
         | But if so, it's boring in that it should have little to do with
         | prime numbers. Let me think about this. (The story of complex
         | numbers and projective transformations is not boring, of
         | course, it's quite pretty, just doesn't provide much of an
         | insight into the primes; and, in turn, its connection to
         | hyperbolic geometry, most widely known through Escher's
         | drawings, is also quite wonderful, but removed even further
         | from the original picture, so might not be necessary to
         | understand it.)
         | 
         | [1] https://en.wikipedia.org/wiki/Ulam_spiral
         | 
         | [2] https://arxiv.org/abs/math/0210327
         | 
         | [3] https://math.ucr.edu/home/baez/week199.html
        
           | shaunxcode wrote:
           | The thing I found was that if you start the spiral with a 0
           | you get a similar pattern. Further if you layer each of the
           | triangular sections you get a really cool pattern[0].
           | 
           | [0] https://lh4.googleusercontent.com/proxy/Ls_8QQgRDf4oK6Fwl
           | iJ7...
        
         | noasaservice wrote:
         | Hmm.. I keep looking at your first (
         | https://www.gibney.org/images/size02/-1_-1_to_1_1.jpg ) image,
         | and I swear it looks 3 dimensional positively curved space,
         | with vertices intersecting in depth. Just that since it's a
         | picture, its being compressed from 3d->2d.
         | 
         | Even though the lines are curved, I'm parsing them as
         | straight.. somehow. Perhaps this is the wrong projection, and
         | maybe it needs to be mapped on a sphere using lat/lon/alt
         | (parametric)? That would also explain the infinite border
         | asymptotes, and going from 2d mercator->spherical would modify
         | those.
        
         | pilotneko wrote:
         | Nice work. You might be interested in this visualization of the
         | first million prime numbers from UMAP: https://umap-
         | learn.readthedocs.io/en/latest/exploratory_anal...
        
       | paxys wrote:
       | Solves a prime number conjecture, not _the_ prime number
       | conjecture
       | (https://en.wikipedia.org/wiki/Goldbach%27s_conjecture).
        
         | ouid wrote:
         | typical Quanta though. I am pretty close to no longer clicking
         | on their links.
        
         | paulpauper wrote:
         | if it was _the_ conjecture, it would be in the headline
        
         | Melatonic wrote:
         | At first this is what I thought was solved - still cool
         | regardless though!
        
         | [deleted]
        
         | raverbashing wrote:
         | It's the Erdos primitive set conjecture
         | https://www.maths.ox.ac.uk/node/36408
        
         | Sniffnoy wrote:
         | I mean, there isn't anything known as "the prime number
         | conjecture". Goldbach's conjecture is a prominent conjecture
         | about primes, but it's not "the prime number conjecture".
        
           | paxys wrote:
           | Goldbach's conjecture is possibly the most famous unsolved
           | problem in mathematics. When people refer to prime number
           | conjecture, this is the most obvious one everyone's thoughts
           | will go to.
        
         | alisonkisk wrote:
         | Goldbach's Conjecture is not _the_ Prime Number Conjecture ,
         | because there is no such thing. There are several prime number
         | conjectures.
        
         | deathgripsss wrote:
         | When I initially read the headline I was stunned
        
           | imranq wrote:
           | Same. Especially the "side project" part
        
       | t_mann wrote:
       | Can we also talk about how this guy is in the third year of his
       | PhD and has no less than 18 papers listed under "major/recent
       | publications", all but two of which are published, and one of the
       | latter 'shocked' the math community?
        
       | Victerius wrote:
       | Link to Arxiv pre-print: https://arxiv.org/abs/2202.02384
        
       | renewiltord wrote:
       | > _The conjecture deals with primitive sets -- sequences in which
       | no number divides any other. Since each prime number can only be
       | divided by 1 and itself, the set of all prime numbers is one
       | example of a primitive set. So is the set of all numbers that
       | have exactly two or three or 100 prime factors._
       | 
       | Minor clarification: exactly k prime factors, counted with
       | multiplicity
        
       | nabla9 wrote:
       | > Mathematicians noted that the work is particularly striking
       | because it relies entirely on elementary arguments. "It wasn't
       | like he was waiting for all this crazy machinery to develop,"
       | Thompson said. "He just had some really clever ideas."
       | 
       | the proof: https://arxiv.org/pdf/2202.02384.pdf
       | 
       | Last time I saw something so simple that I think I could
       | understand the idea because it has not too many new concepts was
       | Hao Huang Sensitivity Conjecture:
       | http://www.mathcs.emory.edu/~hhuan30/papers/sensitivity_1.pd...
       | Donald Knuth further simplified it into one page
       | https://www.cs.stanford.edu/~knuth/papers/huang.pdf
       | 
       | These kind of proofs are very creative.
        
         | zasdffaa wrote:
         | I get creative, but comprehensibility eludes me. To some
         | https://www.cs.stanford.edu/~knuth/papers/huang.pdf may be
         | obvious in its statements and steps and I guess that, aside
         | from having the necessary background in this area, they
         | fundamentally differ from me in how they 'see' this. They the
         | underlying meaning, to me it's a jungle.
         | 
         | Take the statement of the problem
         | 
         | ??? ??? ? ?? ? ??? / ? ???????? ?? ??? ????? ? ???????? ?
         | ?????? ???? ?? ????? ? ? ?????? ??? ?? ?
         | 
         | ok, so you can't C&P from that PDF :) by hand then: "Any set H
         | of 2^(n-1) + 1 vertices of the n-cube contains a vertex with at
         | least sqrt(n) neighbors in H"
         | 
         | Nothing in that makes intuitive sense to me except vertices
         | will have neighbouring vertices. It's not even dimension
         | limited and I can just about manage 4 dimensions at a push.
         | 
         | Next, a bunch of recursively defined 2x2 matrices with no
         | apparent link to anything. I'm lost twice now. Yet to a Knuth
         | or a Von Neumann, it just makes sense. This stuff makes me feel
         | like a different species.
         | 
         | Just a reflection on things. Professional mathematicians in-
         | chimings welcome.
        
           | ouid wrote:
           | the combinatorial object "the n-cube" is just length n
           | bitstrings, neighbor means one bit flip away. It can be
           | thought of as being embedded in the geometric n cube.
           | 
           | the recursive matrices as they are defined are, if you ignore
           | the signs, the incidence matrices of the n cubes. This is
           | only mentioned in the final line of the paper (which is not
           | totally unreasonable). The rest of the result is just some
           | pretty basic facts in linear algebra, but you still have to
           | be comfortable with linear algebra in order to see why they
           | might be natural constructions.
        
             | zasdffaa wrote:
             | How is the bitstring 'embedded' in the n-cube? It must be a
             | linearisation from a 1-dimensional string to vertices of
             | the n-dimensional object but...? What does 'embedded' even
             | mean, mathematically.
             | 
             | Edit: neighbouring vertices can't be collapsed to a 1-dim
             | string such that each bit x in the string abuts bit y if x
             | is a neighbouring vertex of y (neighbouring = 1 edge away).
             | Works for 1 and 2 dim cubes (line and square) fails for 3.
             | Maybe am missing something.
             | 
             | 'incidence matrices' something is incident on something
             | else? It occurs to me that in some sense the recursive
             | matrices might represent the n-cube, each sub-matrix being
             | an n-1 cube. If this is so it is starting to make a little
             | sense.
             | 
             | But that's not the point, which is, how are you seeing this
             | so clearly? It's like a pea-souper over at my end.
             | 
             | (https://en.wikipedia.org/wiki/Pea_soup_fog)
        
               | thaumasiotes wrote:
               | > Edit: neighbouring vertices can't be collapsed to a
               | 1-dim string such that each bit x in the string abuts bit
               | y if x is a neighbouring vertex of y (neighbouring = 1
               | edge away). Works for 1 and 2 dim cubes (line and square)
               | fails for 3. Maybe am missing something.
               | 
               | It sounds like you're missing something. A 3-dimensional
               | cube has 2^3 = 8 vertices:                   x   y   z
               | 0   0   0         0   0   1         0   1   0         0
               | 1   1         1   0   0         1   0   1         1   1
               | 0         1   1   1
               | 
               | Since there are three dimensions, each vertex has three
               | neighbors. If you imagine the vertex at (0, 1, 1), you
               | can travel across the x-dimension to the neighbor at (1,
               | 1, 1), or across the y-dimension to the neighbor at (0,
               | 0, 1), or across the z-dimension to the neighbor at (0,
               | 1, 0). Obviously, you represent this by flipping the x-,
               | y-, or z-bit in the corresponding bitstring
               | representation. The bitstring representation itself is
               | blindingly straightforward: the vertex at (0, 1, 1) has
               | the representation 011, etc.
               | 
               | It's not really clear to me where you're becoming
               | confused?
               | 
               | > What does 'embedded' even mean, mathematically.
               | 
               | In this case, it means that a complex structure (the
               | cube) includes a simpler structure (the collection of
               | discrete bitstrings). You can analyze the bitstrings by
               | themselves if you want to, or you can imagine them as
               | being the vertices of a cube that may or may not have
               | properties other than its vertices, but however you
               | describe the cube, it will include the bitstrings.
        
               | zasdffaa wrote:
               | > It's not really clear to me where you're becoming
               | confused?
               | 
               | Got it. I was interpreting the bitstring as 1 bit mapped
               | to each vertex of the cube, I so badly, utterly
               | misinterpreted it (my string would be 2^n length, not
               | n-length). A simple example and the intent here is
               | totally clear. I guess the problem is at least partly I
               | tend to read what I expect, not what's there. Sigh.
               | 
               | > In this case, it means that a complex structure (the
               | cube) includes....
               | 
               | Righto, a model of interest, a *-morphism or bijection
               | between the string-set and the cube (where * =
               | iso/homo/auto/whatever, it's been a long time)
               | 
               | Thanks for this.
        
       | mwest217 wrote:
       | It's always fun to see one of these articles pop up about someone
       | I know - I knew Jared from the ultimate frisbee team at
       | Dartmouth!
        
       | paulpauper wrote:
       | It shows how there are two types of mathematics; research-level
       | math in which important stuff is proved, and then
       | teaching/pedagogical math, which doesn't get as much attention. I
       | don't think teachers, authors get enough credit. There are also a
       | huge differences in individual ability eve between math PHDs and
       | profs. This may see obvious but the differences can be huge.
        
       ___________________________________________________________________
       (page generated 2022-06-06 23:00 UTC)