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Feb-04-21
 | | MissScarlett: <<chessgames.com> Two moves are recorded incorectly: It should be 54...Ra7 and 62...Ra6. Can you please fix it?> Alekhine vs Duras, 1910 (kibitz #1) It's a long time ago, but can you recall what source you had for the game? As <mifralu> points out, Skinner & Verhoeven, based on the tournament book, have <54. ... Ra8> and <62. ...Ra7>. |
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Feb-05-21
 | | Gypsy: <MissScarlett> I do remember the source, it was a Czech monograph about Duras written by a team of IM's led by Josef Louma. Of the top of my head, I remember also that the team included Emil Richter. (Given that this was mainly an end-game struggle, E. Richer was likely the one who analyzed the contest.) I also have a later Duras monograph written by Jan Kalendovsky, but I acquired that one later. I would love to verify the moves I gave -- I do goof up more often than I care for -- but I am still socially distant, away from my city house and away from my book cases. |
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Feb-05-21
| | Gypsy: <Everett> Among the curves the Sweedish Covid 19 Wikipedia page https://en.wikipedia.org/wiki/COVID... displays towards the bottom is one that breaks down the all-cause-death-rate by the three largest counties: Stockholm, Skane, and Vastra Gotaland. The comparison between Stockholm and Skane is quite instructive. In particular, note that the second season of COVID in Stockholm is already much tamer than was the first COVID season there. In contrast, it looks like Skane lucked out during the first COVID season. But Skane is being hit hard now, in the second COVID season. I believe that what we see in these curves is the effect of COVID attacking an unprepared population cluster for the first time. |
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Feb-05-21
| | MissScarlett: <The first move 54...Ra7 was a part of a key trap that Duras set for Alekhine.> Did you mean by this that ...Ra7 was crucial to Alekhine's plan? If so, I don't see the significant difference between it and ...Ra8. |
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Feb-05-21
| | Gypsy: <MissScarlett> The trap got completed when Duras played <61...Kd7>. Now, AAA can play his <62.d5?!>, because after <62...exd5? 63.Bxf5+ gxf5? 64.Rg7+ ...>, the rook on a7 is lost on the account of the x-ray. (Had the rook been on a8, there would not been the temptation for AAA to play the 62.d5... because 62...exd5 is no longer a tactical error) |
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| Feb-09-21 | | Everett: <I believe that what we see in these curves is the effect of COVID attacking an unprepared population cluster for the first time.> I agree |
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Feb-27-21
| | Gypsy: The all-cause-deaths graph for Sweden has been brought up-to-date. (That presently means week 5, as the system seems to need about three weeks for reporting and processing) The numbers look very promising and the Swedish death rate is now significantly below the null-hypothesis mean for the season. https://upload.wikimedia.org/wikipe... The speed of the Swedish recovery outpaced even my personal dead-reckoning. (Trying to be slightly on the conservative side of things, I was thinking that mid-March would see us to this milestone) |
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Feb-28-21
 | | OhioChessFan: Could you translate the last graph's headers? |
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Mar-02-21
| | Gypsy: Antal Dodsfall ~= the number of death-cases
Ar och vecka ~= Year & week |
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| Aug-14-21 | | Tiggler: Hello, Gypsy, are you still there? If so, I'd like to talk to you about Hardy-Weinburg equilibrium (ask your wife), and its relevance to vaccination choices. Best regards. |
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Aug-23-21
| | Gypsy: <Tiggler> How can I help? |
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| Aug-25-21 | | Tiggler: It concerns a bit of ethnobiology that was in vogue in the 1980s. The argument was that altruistic behavior could be explained if the opposite, antisocial or selfish behavior, was penalized by others. If those who persist in selfish behavior, however, are at a low enough frequency they can enjoy most of the benefit of a socially cooperative society without much cost. Such individuals were termed 'cheaters'. The analogy to vaccination rates is obvious. It is not really Hardy-Weinberg, because that concerns genetic effects of rare heterozygotes. The analogy arises because the cost/reward depends on the population frequency, and hence an equilibrium can arise. Thoughts? |
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Aug-25-21
| | Gypsy: Let me recap in different words. That way you can check my understanding: We have two 'extreme' but opposite behaviors: extreme sacrifice and selfish cheating. We also have two explanatory mechanisms: biological fitness function and game-theoretical payoff function. ------------------
An example of a voluntary extreme sacrifice principle can be a mother [insert your species here] that tries to fight off a predator to save her young ones. Another example of extreme sacrifice, this time involuntary, could be the infamous cytokine storm, where the immune-system of an organism sacrifices the individual to protect the herd. For a paradigmatic example of cheater behavior, we can take the troubling state of measles vaccination on Vashon Island (suburb of Seattle, WA). -- Too large a number of measles vax-refusers on Vashon has created a herd-immunity issues for local schools. https://www.q13fox.com/news/vashon-... [All examples from biology. I presume You are interested in those] |
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Aug-25-21
| | Gypsy: <Hardy-Weinberg Principle>, from the standpoint of stochastic processes, says that the random-mating mechanism (uniform random mating, really) is idempotent and that it produces an equilibrium distribution of gene-pairings in one generation. (Its worth realizing though that the distribution of gene pairs is a subject of random-walk drifts and that this does not contradict the Hardy Principle. The drift can either be systematic due to changes in survival rates or be purely random) What Hardy-Weinberg Principle really explains is the math behind the original Gregor Mendel experimental result. Intuitively, one would expect additional changes, from first generation to second generation, from second to third, and so on. Yet, the distribution stays stable (modulo the drift issues) |
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| Aug-26-21 | | Tiggler: In your last message (to take that one first) you fail to mention selection: the bias for or against survival of one type over another. The original work was specifically for diploid sexually breeding populations. Diploid means that each individual gets two copies of the gene at every locus. The resulting phenotype depends, when the two copies are different, on which of the two is dominant. H-D arises at a gene locus if heterozygotes are selectively favored over either of two homozygous types. This prevents the less fit gene from being driven from the population (over many generations). The effect is dependent on prevalence: a rare gene is seldom found in homozygous individuals, so even if it is fatal in homozygotes it can remain in the population if the hetrozygotes are advantaged over homozygotes of the "good" gene. The equilibrium frequency (prevalence in population) depends on the fitnesses of the three diploid types. |
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| Aug-26-21 | | Tiggler: An example is sickle cell anemia: the homozygotes are severely disadvantaged but the heterozygotes have a slightly favored response to malaria. Thus in populations where malaria is endemic, the rare genotype survives at low frequency. |
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| Aug-26-21 | | Tiggler: On Vashion Island there are two issues that prevent selection from solving the problem:
1. the population is not isolated in mating patterns, and 2. good medical care prevents cheaters from suffering the full cost of their vax-refusal. |
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Aug-28-21
| | Gypsy: In my view, the Vashon Island case is really a problem of game theory, not of natural selection. People are minimizing the threat to themselves, or to their children. Under a rational-decision hypothesis, one would probably formulate the problem as each choosing the strategy that minimizes the probability that they will come down with the disease. (In reality, people minimize their fear. They chose intuitively, without tabulating the probabilities. Modeling subjective freakouts is too nebulous/dicey, however, so lets use probability as auxiliary objective.) If everyone in the community is vaxed, the herd is safe and the only risk to an individual comes from that individual's potentially bad reaction to the vaccine itself. This probability is positive, not zero. Thus the everyone-vaccinated-state is not really a Nash point: Locally, people can further reduce their risk by refusing the vaccination, as long as the herd remains immune. Prisoner's Dilemma arises: If too many people act 'smart' and refuse the shot, the whole herd loses its immunity and the disease resurfaces. That motivates the people to return to vaccinating. When using probabilities as proxy, one can expect an equilibrium of sorts to form, where the expected harm from vaccine malfunction sort of equals to the expected harm from a wild, unprotected encounter with the disease. Knowing how irrationally people freak out about things, however, even this equilibrium is unlikely to be achieved in real life over protracted time. |
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| Aug-29-21 | | Tiggler: Your preference for a game theory formulation is a valid choice, but I would argue that, so far as equilibria are concerned, it makes no difference to the outcome. In one case all individuals are rational (!) and make a random choice with a fixed probability, whereas in the other the individuals are predisposed to make different choices and the frequency of different types in the population determines the probability of each choice. Of course the attainment of equilibrium will not occur in practice in either case, but it is interesting to know the direction towards which the selective pressure (again a biological metaphor) operates. |
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Sep-04-21
| | Gypsy: Key facts about competitive Fixed-Points in Game Theory: (1) Existence of a fixed-point is often proved by indirect means, usually via the Brouwer's Fixed-Point theorem. (2) The natural process of all players repeatedly optimizing their individual utility function may not ever find a fixed-point; examples of circulations in games have been constructed. (3) Many cases of competitive fixed-points produce globally sub-optimal results. The most infamous of these is found in the Prisoner's Dilemma paradox. (4) Computational methods to find equilibrium are usually based on piecewise-linear homotopy methods, a generalization of Lemke's Algorithm for solving general quadratic optimization problems. (From a given start, PL-homotopy algorithm also may but may not find an equilibrium along its path.) (5) An extraordinarily useful notion is that of Nash Equlibrium, namely of a point where no player can improve their own utility function by acting alone. (6) This leads to the notion of cooperative games. (Most of the fundamental theoretical work there was done by Lloyd Shapley, often in a partnership with Martin Shubik) |
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| Sep-09-21 | | Tiggler: I don't think any of those theories deals with domestic terrorism. That is a component of the problem in the US, perhaps less so in the EU. |
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Sep-09-21
| | Gypsy: From the philosophical standpoint, Game Theory is successful where the game's players are essentially automatons. They have little or none of "free will" and their behavior or playing strategy is dictated by their utility function, payoffs, forces of optimal solutions, and so on. In a sense, the Game Theory framework here is a modeling artifice and, no matter how useful, Lloyd Shapley called these "Nonessential Games". Real life is much more complicated than that. (I sincerely hope!) |
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| Sep-10-21 | | Tiggler: <(I sincerely hope!)> Well, be careful what you wish for! |
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Sep-10-21
| | Gypsy: <Tiggler: ... Well, be careful what you wish for!> I understand your concern, I think. However, having spent 1/3 of my life on the receiving end of a totalitarian regime's 'wisely dished out bliss', I put my trust in the complexity of each person's individual decision making. It is a sort of religion with me. |
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Sep-10-21
| | Gypsy: It is interesting to speculate where on the scale of non-essential games is chess. It seems too me that the more forced are the variations the more 'non-essential' we are, as players. That is, as long as we do find the non-blunder moves. That is kind of essential, but in a different sense of the term. |
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