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Research demographics again

  1. Mar 6, 2004 #1


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    Research demographics came up again, in the "Shadow States" thread
    "...This is pretty much how most theorists have felt about LQG from it's inception."
    raising majority/minority issues and motivated me to do another arxiv keyword search for String-related papers and LQG-related papers.

    I came up with the following numbers for years 2000 to date. The last entry, LTM, is for the last twelve months as of 5 March 2004.

    Code (Text):

    year    String   Loop

    2000    1491      80
    2001    1455      86
    2002    1342     111
    2003    1074     123
    LTM      833     132
    the boolean keyword search expression I used for String was
    string OR brane OR braneworld OR D-brane OR M-theory OR p-brane
    looking for occurrences in the preprint's abstract.

    the search expression for Loop-related papers is one I use regularly to check for new pre-prints and have described in another thread.
    It searches the abstract for occurrences of
    loop quantum gravity
    loop quantum cosmology
    quantum gravity phenomenology
    discrete quantum gravity
    canonical quantum gravity
    spin foam
    doubly special relativity

    Readers are welcome make up their own keyword search expressions to put into the arxiv.org engine. They will get different results for sure. I have been finding an increasingly close relation between LQG and DSR, so I include doubly special relativity in my search. You may choose not to. Discrete quantum gravity is what Gambini and Pullin call their brand of LQG, so one needs it to get their papers. The boolean expression is something to play around with some, not to take on faith. And it is not clear that the numbers mean a great deal.
    Last edited: Apr 14, 2004
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  3. Mar 20, 2004 #2


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    Keep it honest and stick to the facts

    Apropos head-counts, sheer numbers dont always tell the story:
    here's a bit from Urs report of March 14, for balance.

    Urs is reporting from the Spring 2004 conference of the German Physical Society (DPG) at Ulm
    -----exerpt from Urs-----
    Before the talk I met Rüdiger Vaas, who is science journalist for the german popular science journal Bild der Wissenschaft and is working a lot on reporting about research in quantum gravity. I had first met him at the Strings meet Loops symposium last year. His report on ‘Strings meet loops’ will appear in the next issue of BdW.

    He tells me that more than half of the 12 pages long article will be concerned with LQG and in particular with M. Bojowald and his ‘Loop Quantum Cosmology’. Considering that also the recent issue of Scientific American had an article by Lee Smolin on LQG, which of course can be found translated in ‘Spektrum der Wissenschaft’, and considering that Spektrum and BdW are the two leading german journals for popular science, this gives an impressive amount of public attention for LQG here in Germany. Maybe there is a general tendency. The DPG Symposium here in Ulm is clearly dominated by LQG contributions. Kind of amazing when one is involved in the current discussion about the conceptual viability of LQG.
    -----------end quote------

    Here's a link to Urs full account which has lots of other exciting things to comment on:

    From Urs report one cannot say that the upsurge in interest in LQG is limited to the popular press as distinct from the physics community. At least from this it appears to be happening in both venues: among researchers at the conference and also in popular magazines like Bild der Wissenschaft and Spectrum der Wissenschaft.

    I think it is interesting that the lead in LQG research seems taken to a large extent outside the USA. Researchers in Germany and France seem to be in the forefront (but also in a number of other countries).
    The USA theoretical physics establishment may have a little more inertia and be a little more set in its ways. I cant say why but one gets a distinctly different perspective if one looks only in the States as compared with the global picture.

    (recent conferences or ones soon to take place in Germany, Poland, India, Mexico, Brazil, France)
    Last edited: Apr 14, 2004
  4. Mar 21, 2004 #3


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    It has been over a month since my check on 5 March, so I ran the same LQG keyword search again as of today, 8 April.

    Code (Text):

    year    Loop(3/5)   Loop(4/8)

    2000    80          80
    2001    86          86
    2002    111         111
    2003    123         123
    LTM     132         131
    as we move along in 2004 the LTM "last twelve months" count becomes more of a window on 2004 and less representative of research output in 2003. It might therefore be expected to increase, assuming output is higher this year. But although there is some fluctuation I dont see any clear trend. Indeed the LTM figure is slightly less but about the same as it was a month ago.
    thanks Haelfix, for the next-in-series post!
    several very sensible considerations you mention
    (which can affect areas of research in other fields as well,
    research lines have a lifecycle and sometime pause and get
    fresh input from somewhere) may well be applicable here,
    anyway I agree with general tenor but wont devote
    a post to saying so
    Last edited: Apr 14, 2004
  5. Mar 21, 2004 #4


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    I think some of the interest in LQG comes from the fact that String theory has had so many papers written about it. Its hard to innovate in a field where so many smart people have been working for so long.

    I also consider String theory considerably harder, both conceptually and mathematically. There are so many toy models that one has to be familiar with, including all the notation that is hardly consistent between papers.. Essentially it feels like studying QFT on steroids! And QFT is already hard enough. A few subdomains are a little easier (eg studying blackholes) b/c at least some qualitative experience with the semiclassical theory can go a long way in clearing up things.

    LQG has the nicety that it still feels like quantum mechanics and General relativity (with only a few extra things added into the mix), and that it is treating something everyone considers important (background independance). Many string theorists, even if they don't believe in LQG as it stands now, feel that some of those methods may be utilized at some point in the development of stringy physics.
  6. Mar 22, 2004 #5


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    The interest in LQG comes from a basic belief about how theory selection should work in quantum gravity in it's current state. People attracted to LQG think it should come from the bottom up. Specifically, one must begin with some basic principle - in the case of LQG, background independence - and then a theory, no matter how implausible, must be constructed to embody it.

    People attracted to string theory on the other hand see that it's consistent with and contains both GR and QFT and extends them both in remarkable but not completely understood ways. The idea now is to discover what the basic principles underlying this theory are, the idea being that it's unlikely we can simply guess them, as LQG people think, before we even begin. It's worth mentioning yet again that strings remains the only bonafide quantum theory of gravity we've ever found.

    Precisely, so people rationalize pursuing LQG since they're simply too intimidated by strings.

    As I said, LQG seems less intimidating.

    Yes, but unlike people in these public forums, researchers aren't vulnerable to arguments that this should be all that matters or even the place to begin.

    I'm sorry, but there's not one scintilla of evidence or suggestiveness that spin-networks etc could bear in any way on strings. In fact a major part of activity in LQG has been to convince string theorists that it contains something of relevance for them. But LQG is a very simple (naive, contrived etc.) theory, so it's clear there simply isn't anything in there of interest to string theorists. In fact the most recent attempt to show otherwise, namely the LQG-string, actually revealed in rather stark terms why LQG is unphysical. The author of the paper, thomas thiemann, tried to defend it, but was quickly convinced that it was indefensible. As a result, the very small number of people currently doing LQG are scratching their heads over this.
    Last edited: Mar 22, 2004
  7. Mar 23, 2004 #6


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    This argument is not very honest. Both string theory and LQG rely entirely on conceptual and mathematical prejudices (different ones certainly, but still there). They have to. There is no experimental guidance, so all we can say is that we hope things behave a certain way, and that certain limits exist. There have to be many constructions that have these limits (and its not completely clear that either strings or loops are in this class), but few (0-3) are known which actually seem reasonable based on our expectations of how the universe should work.

    I find it amusing that you think the many unjustified aspects of string theory are a virtue ("...extending both GR and QFT in remarkable ways..."). Speculative theories should have as few assumptions as possible. Of course we come back to aesthetic prejudices again in deciding exactly what "as few as possible" means. Many people believe in string theory because it conforms to certain mathematical principles that they like. The LQG people have different principles they consider most interesting. Why is one objectively better than the other?

    Yes they are. Some researchers think background independence is fundamental and others don't. There is no objective reason that the "lessons" of GR should be less important than those of QFT. This is again a personal choice.

    From talking to people working in LQG, this is not correct. There were certainly issues with that paper, and I wish I remember what those were right now. They were not fundamentally damaging to the ideas of LQG. I highly doubt that all string papers are perfect either...
  8. Apr 14, 2004 #7


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    Hi Haelfix, you make some good points here that I want to try to emphasize and remember.
    --if (if) string is losing popularity it could be by no fault of itself but simply because the field has been worked so much

    --if loop is gaining popularity (as you suggest and also born out to some extent by arxiv count for what that is worth) then it might be by no intrinsic merit but because the string field is overworked and loop is one possible alternative for doing research

    --loop has the nice feature of being conservative of QM and GR and feeling like home to someone familiar with those established ways, plus advances made in loop might, you say some string theorists suspect, be able to be utilized outside that context and perhaps be helpful to them. so it is not a zerosum situation, so to speak

    these points seem to me to send a good message and so I dont want them to go away immediately, maybe someone can add or elaborate
  9. May 13, 2004 #8


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    Periodically I update the LQG count of papers at the arxiv.
    I do not bother to do a similar update for the count of string theory papers since it's not my primary interest. The last update was at the beginning of March, two months ago.

    I added "nonperturbative gravity" to the keyword list because the search missed the landmark paper of Ambjorn Jurkiewicz and Loll that came out recently. With that addition the LQG counts are, as of 12 May 2004

    Code (Text):

    year     Loop

    2000     82
    2001     95
    2002     117
    2003     131
    LTM      140
    the "LTM" entry is for the "last twelve months"----research papers posted
    at the archive between 12 May 2003 and 12 May 2004.
    the boolean expression of keywords is stored in my browser: I'd be happy
    to post it, if anyone is curious, exactly as it is entered into the arxiv search engine.
  10. May 28, 2004 #9


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    Today one of us PF posters again raised the issue of raw output
    of stringy research papers

    -----quote from not even wrong thread----

    These remarks are completely wrong and misleading: The numbers of highly cited papers can't reliably gauge the amount of activity in a research program since this number could be very low even though the total number of papers published - this being a far more accurate measure of levels of activity - is very high.

    --------end quote------

    So I just now went to arxiv search and got a figure for the last 12 months output of string papers---- 844.

    (this is down from roughly around 1400 to 1500 per year, a while back)

    In case anyone else wants to get arxiv search counts here are the keywords I used: ABSTRACT=

    string OR brane OR braneworld OR D-brane OR M-theory OR p-brane

    selfAdjoint commented in the Not Even Wrong thread about a perceived "flat-lining" in HEP research in the past 5 years, or starting some 5 years ago. this was born out by the fact that in 1999 there were some 17 highly cited (125 citations or more) recent (4 year window) string papers.
    While by contrast in 2003 there were only 3 such papers----that is highly cited and recent by the same criteria.

    Research papers' citations are sometimes used (rightly or not) as a rough measure of research quality or importance.

    But let's not refer to the quality, since it is hard to measure, and may be a sore point. Let's simply say there has been a marked decline in the *raw number* of string papers.

    In this light BTW, the recent remarks of Lubos Motl quoted by Peter Woit seem particularly significant (and also Susskind's anthropistical posture, upon which Motl frowns).
    Last edited: May 28, 2004
  11. May 28, 2004 #10


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    You're the one who - and nobody asked you to do this - initiated and maintains this thread, entitling it "Research demographics again". What little I've contributed to this subject is largely in response to you "again" raising this issue and then dealing with it in a way purposely meant to distort what to everyone else is the uncontroversial truth: STRINGS RULE!

    Highly cited papers are certainly seminal in some respect. The common theme characterizing the 2nd string revolution and underlying virtually all of the highly cited stringy papers over the last decade is probably D-branes. The reduction in such highly cited papers merely reflects the fact that D-branes may have taken us about as far as they can on their own and that we need new tools to auger the next revolution in string theory, and hence in high energy theory. However, even in the absence of such a breakthrough, stringy papers continue to dominate high energy theory and drive to a considerable and growing extent theoretical cosmology.

    It's hard not to conclude from your obsession with finding ways to fool people about the true status of string theory in the physics community that you're afraid of it. What is it about strings that worries you so much? After all, it's not like you have a professional stake in this game. Maybe it has something to do with protecting your social status and importance at PF as you perceive them. (This wouldn't surprise me since the sheer volume of material you post daily and the effort you put into managing your relationships with other members indicates that PF must pretty much be your whole life).
    Last edited: May 28, 2004
  12. May 28, 2004 #11
    "...So I decided a few years ago to ignore their advice and try to construct the background independent form of M theory. In the process of inventing loop quantum gravity, we gained a lot of knowledge about how to make quantum theories of space and time that are background-independent. We have a mathematical language, we have a conceptual language, we know what questions to ask, and we know how to do calculations. It turns out that there is a lot of loop quantum gravity that can be generalized and extended by adding extra dimensions and extra symmetries in order to make it a suitable language for M theory.

    At first some of my friends and collaborators were shocked that I was working on string theory. However, I had an idea that maybe string theory and loop quantum gravity were different sides of the same theory, much like the parable of the blind men and the elephant. I spent about two years working on string and M theory, with the goal of making them background-independent and thus unifying string theory and loop quantum gravity. I did find some very interesting results. I was able to build a possible background-independent formulation of string theory.

    The most interesting results I found use some beautiful mathematics, having to do with a kind of number called an octonion. These are numbers that you can divide, but they fail to satisfy the other rules, such as commutativity and associativity. Feza Gürsey, from Yale University and his students, especially Murat Gunyadin, have for years been exploring the idea that the octonions might be connected to string theory. Using octonions, I was able to develop an attractive idea (from Corrine Manogue and Tevian Dray of Oregon State University) that explains why space may look three-dimensional while being, in a certain mathematical sense, nine-dimensional. I don't know if the direction I took is right, but I did find that it is indeed not so hard to use background-independent methods to formulate and study conjectures about what M theory is.

    Working on string theory using the methods from loop quantum gravity was a lot of fun. I was out there with just a few friends, as it had been in the early days of loop quantum gravity, and I made real progress. "

    Lee Smolin

    -this sounds like somethig worthwhile to me-


    /:set\AI transmedia laboratories

    http://setai-transmedia.com [Broken]
    Last edited by a moderator: Apr 20, 2017 at 9:35 PM
  13. May 28, 2004 #12


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    Me too, the quote is from page 6 of an essay which is well worth reading in entirety.

    setAI, thanks for spotting it and calling attention.
  14. May 29, 2004 #13
    Background versus Background Independent


    "What is space and what is time? This is what the problem of quantum gravity is about. In general relativity, Einstein gave us not only a theory of gravity but a theory of what space and time are--a theory that overthrew the previous Newtonian conception of space and time. The problem of quantum gravity is how to combine the understanding of space and time we have from relativity theory with the quantum theory, which also tells us something essential and deep about nature."

    Edge Bio http://www.edge.org/3rd_culture/bios/smolin.html


    From this, the questions about this relationship of string theory versus LQG needed some clarification to me. Is this the question of what is discrete versus continuity?

    Loop quantum gravity predicts that space itself is discrete. Just like matter may appear to be smooth, but is actually made from discrete atoms, the apparently continuous nature of space is replaced by a discrete network, or weave of tiny loops. These are sometimes called spin networks. The result is that geometric quantities such as volume or area turn out to be quantized—like the quantized energy levels of an electron in an atom, they can only come in certain discrete units.

    http://www.perimeterinstitute.ca/explore/what_we_research/quantumgravitylong.cfm [Broken]

    And along this same line where had Smolin gone? :smile: So it's good to keep in touch with the resources from the PI institute and what they have been doing. For the Arm Chair researcher of Warp Space time http://www.perimeterinstitute.ca/explore/warped_spacetime.cfm [Broken] is always interesting.

    Why the desire to combine relativity theory (i.e. gravity) with quantum theory? First, such a unified theory will be needed to answer many profound questions, including: How did the Big Bang begin? Or: What is happening deep inside a black hole? But more importantly, the history of physics has taught us again and again that successful unifications of seemingly disparate theories are a natural direction of progress in physics, invariably leading to deeper insights into—and more profound questions about—the workings of our mysterious universe. The search for a quantum theory of gravity, which strongly challenges the entire foundation of our understanding of the universe, promises to be the greatest unification of all.

    http://www.perimeterinstitute.ca/explore/what_we_research/quantum_gravity.cfm [Broken]

    Arguably the most important development in this cycle has been the birth of the new field of science called quantum information theory. It is well-known that modern computers process information based on laws of nature that date back to Galileo and Newton. Theoretical physicists such as Richard Feynman, David Deutsch and others wondered if it might be possible to build an entirely new kind of computer based, instead, on the more accurate and powerful quantum laws, i.e. a quantum computer. It was realized that such a computer would be vastly more powerful than any conventional computer could ever be. Subsequent developments have now brought us to the brink of what might be called the “quantum information age”. On the horizon are wildly fantastic possibilities, including: quantum computers, absolutely secure quantum communication systems and quantum teleportation, to name a few. A more detailed description of the ideas and future potential of quantum information theory can be found here.

    http://www.perimeterinstitute.ca/explore/what_we_research/quantum_information.cfm [Broken]
    Last edited by a moderator: Apr 20, 2017 at 9:36 PM
  15. May 30, 2004 #14


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    Hi setAI,

    So you're a physicist, right?
  16. May 30, 2004 #15
  17. May 30, 2004 #16

    nope- :smile:


    /:set\AI transmedia laboratories

    http://setai-transmedia.com [Broken]
    Last edited by a moderator: Apr 20, 2017 at 9:37 PM
  18. May 30, 2004 #17


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    Well, welcome to PF! :surprise: (Don't read anything into the smilie. I just really like this particular one.)
  19. May 31, 2004 #18


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    Let's see if this link works:

    it is for the past 12 months submissions to arxiv
    where abstract summary has the words
    string OR brane OR braneworld OR D-brane OR M-theory OR p-brane
    which database or search engine gets used at arxiv
    seems to follow a weekly cycle so there will be some variation
    in what this link gives (if it works at all) from day to day.

    I just tried it and got about a thousand stringy research papers. Monday at 10 PM or so.

    [edit: I'll repeat the same link for years 2000 up to last 12 months]
    the search engine at arxiv is a bit erratic so results can vary some from day to day

    these are for the non-string QG papers:

    Year 2000:

    Year 2001:

    Year 2002:

    Year 2003:

    Last Twelve Months:

    For Non-string QG the keyword boolean used is:
    ((abs=((loop AND quantum) AND (cosmology OR gravity)) OR abs=((quantum AND gravity) AND ((discrete OR phenomenology) OR (canonical OR nonperturbative)))) OR abs=((spin AND foam) OR (doubly AND special)))

    which covers topics like:
    loop quantum gravity
    loop quantum cosmology
    discrete quantum gravity
    canonical quantum gravity
    nonperturbative quantum gravity
    quantum gravity phenomenology
    spin foam
    doubly special relativity

    Here are similar links to the arXiv search engine for String-related:
    ( abstract summary has the keywords
    string OR brane OR braneworld OR D-brane OR M-theory OR p-brane)

    Year 2000:

    Year 2001:

    Year 2002:

    Year 2003:

    Last twelve months (e.g. 1 June 2003 to 1 June 2004):
    Last edited: Jun 9, 2004
  20. Jun 4, 2004 #19


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    the Stanford/SLAC Spires database has come out with their
    list of most-cited GRQC papers for the year 2003


    This is a good chance to see trends in what is interesting and citable in General Relativity and Quantum Cosmology (gr-qc) papers.
    To make the list short I truncated it at 25 citations----dropped the papers with less than 25.
    To focus on current work, I dropped those from 1999 and earlier ('recent' means preprint appeared in the last 4 years, 2000 thru 2003, eg a preprint with number gr-qc/9910076 would be excluded as not recent because it appeared in 1999.)
    A similar list was put out for 2002 and I thought the change was interesting so I noted change from 2002 in the number of citations. Like the top paper on the list had 58 citations which was up from zero the year before.

    It is interesting to see what topics had a rapid growth in citation-frequency.
    I get the impression it was oftentimes where there is a connection with Quantum Gravity.

    --------quote, non-recent removed, change from 2002 noted------

    2003 highly cited gr-qc papers

    0058 up from zero
    By Olaf Dreyer (Perimeter Inst. Theor. Phys.).
    Published in Phys.Rev.Lett.90:081301,2003 [PS file for arXiv: gr-qc/0211076]

    0057 up from 27
    By Alexander Yu. Kamenshchik (Landau Inst. & Landau Network Centro Volta), Ugo Moschella (Insubria U., Como & INFN, Milan), Vincent Pasquier (Saclay).
    Published in Phys.Lett.B511:265-268,2001 [PS file for arXiv: gr-qc/0103004]

    0055 up from 31
    By Clifford M. Will (Washington U., St. Louis).
    Published in Living Rev.Rel.4:4,2001 [PS file for arXiv: gr-qc/0103036]

    0052 up from zero
    By Lubos Motl (Harvard U., Phys. Dept.).
    Published in Adv.Theor.Math.Phys.6:1135-1162,2003 [PS file for arXiv: gr-qc/0212096]

    0052 down from 57
    By Giovanni Amelino-Camelia (Rome U.).
    Published in Int.J.Mod.Phys.D11:35-60,2002 [PS file for arXiv: gr-qc/0012051]

    0049 up from 36
    By Thomas Thiemann (Potsdam, Max Planck Inst.). [PS file for arXiv: gr-qc/0110034]

    0043 up from 16
    By M.C. Bento, O. Bertolami, A.A. Sen (Lisbon, IST).
    Published in Phys.Rev.D66:043507,2002 [PS file for arXiv: gr-qc/0202064]

    0038 up from zero
    By Vitor Cardoso, Jose P.S. Lemos (Lisbon, IST).
    Published in Phys.Rev.D67:084020,2003 [PS file for arXiv: gr-qc/0301078]

    0036 up from 19
    By Joao Magueijo (Imperial Coll., London), Lee Smolin (Perimeter Inst. Theor. Phys. & Waterloo U.).
    Published in Phys.Rev.D67:044017,2003 [PS file for arXiv: gr-qc/0207085]

    0033 up from 21
    By A. Ashtekar (Penn State U. & Santa Barbara, KITP), John C. Baez (UC, Riverside & Penn State U.), Kiriil Krasnov (UC, Santa Barbara & Santa Barbara, KITP).
    Published in Adv.Theor.Math.Phys.4:1-94,2000 [PS file for arXiv: gr-qc/0005126]

    0030 down from 54
    By Douglas M. Eardley, Steven B. Giddings (UC, Santa Barbara).
    Published in Phys.Rev.D66:044011,2002 [PS file for arXiv: gr-qc/0201034]

    0029 up from zero
    By Gabor Kunstatter (Winnipeg U.).
    Published in Phys.Rev.Lett.90:161301,2003 [PS file for arXiv: gr-qc/0212014]

    0027 up from zero
    By Alejandro Corichi (Mexico U., ICN).
    Published in Phys.Rev.D67:087502,2003 [PS file for arXiv: gr-qc/0212126]

    0026 up from zero
    By R.A. Konoplya (Dnepropetrovsk Natl. U.).
    Published in Phys.Rev.D68:024018,2003 [PS file for arXiv: gr-qc/0303052]

    0026 up from around 10
    By Vitor Cardoso, Jose P.S. Lemos (Lisbon, IST).
    Published in Phys.Rev.D63:124015,2001 [PS file for arXiv: gr-qc/0101052]
    -------I dropped off the tail of the list, those with less than 25 citations-----
    Last edited: Jun 4, 2004
  21. Jun 4, 2004 #20


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    That list is a super way to illustrate how totally dead lqg is. Thanks marcus!
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