Recent content by Kolmin

  1. K

    AM-GM Inequality - Troubles with an example

    Ok, correct me if I am wrong. I think I see now what's going on here. 1) we build up that trick I couldn't see to get rid of everything under the root in the GM side; 2) we have a 3 in the LHS cause it comes from the AM in the RHS; 3) yeah, we do need three elements to implement that trick on...
  2. K

    AM-GM Inequality - Troubles with an example

    Jeez. That's really bad... completely mathematically blind. I am quite ashamed of myself. :redface: Now that I see that 2+2=4, I have some problems that I am afraid will be challenging like 3+3=?. There are some questions I have related with other things I don't understand. 1) Why do...
  3. K

    AM-GM Inequality - Troubles with an example

    Homework Statement Let ##a## and ##b## real numbers such that ##a>b>0##. Determine the least possible value of ##a+ \frac{1}{b(a-b)}## I took this example from page 3 of this paper Homework Equations In the article previously linked, explaining the example, the author writes...
  4. K

    A proof of Dilworth Theorem? - Looking for feedbacks

    Theorem (Dilworth, 1950): Every poset whose width is ##n## is equal to the union of ##n## chains. Proof: We let ##R## be a partial order relation over a set and we let ##P## be an arbitrary poset with width ##w(P)## equal to ##n##. We proceed on induction over ##w(P)##. i) Base case: We...
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    A proof of Dilworth Theorem? - Looking for feedbacks

    It is the very first time I try such a long shot, attempting to prove a well-known theorem (small one, but still not completely obvious). I would be really grateful to anyone ready to give a feedback (contents or style doesn't matter - they are both important). PS: Obviously I am not sure...
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    Solve Card Probability: King of Hearts in Deck

    My two cents: Jim McNamara logic is sound. The problem with your logic is that - if you assume that the tricky side of your problem is not in the way in which it is written, but in some mathematical content - then you have to consider the possibility that you take the 16 face cards from the...
  7. K

    Posets and minimal elements - Looking for an inductive proof

    I don't enter in the discussion about "same size" because my mathematical skills are not that advanced, even if basing on my limited knowledge I would agree with Michael Redei. Btw, going back to my original Case 3 of the proof, I think that this example based on fractions supports exactly my...
  8. K

    Posets and minimal elements - Looking for an inductive proof

    To me even that one looks redundant for the reasons I specified.
  9. K

    Posets and minimal elements - Looking for an inductive proof

    Is it not a bit redundant? My line of reasoning is more or less the same of that I wrote down in my last reply to Michael Redei. I add an element to ##B## and I come out with ##B'##. Now, I assume that ##B## has a minimal element. So, if the new element and the minimal element of ##B## bear...
  10. K

    Posets and minimal elements - Looking for an inductive proof

    Well, don't worry. I appreciate the fact that you had this thought, but it's really not a problem and I didn't feel it. Actually, to be honest, when I started to read your post and I saw "base case" with the inverted commas, at the beginning I thought you wanted to be sarchastic and I kinda...
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    Posets and minimal elements - Looking for an inductive proof

    The server stop gave me enough time to get something hopefully decent that should work. :smile: Still, I have some doubts. Can I prove the result without going backward to the singleton cases? Or, in other words, is there a way to prove it having as a base case the two elements one I...
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    Posets and minimal elements - Looking for an inductive proof

    Statement: Suppose R is a partial order on a set A. Then every finite, nonempty set B \subseteq A has an R-minimal element. Proof: Let B be an arbitrary subset of A. We prove the statement by induction on the cardinality of B. i) Base step: Assume that B is a singleton. Then the only...
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    Posets and minimal elements - Looking for an inductive proof

    Huge mistake..I completely forgot that the notion of set implies that. For a second, I thought that I was implicity assuming that it was a loset and not a poset. So, here we are: indeed I assumed completeness. I don't see why it is the case. This. I was looking for that word! :smile...
  14. K

    Posets and minimal elements - Looking for an inductive proof

    Non native writer... :blushing: BTW, thanks a lot. I really felt it was too wordly.
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