I have two inequalities to show, both of which describe some probabilities. First I know how to handle, and it follows from applying arithmetic-harmonic mean inequality:

consider 9 numbers $a_1,a_2,a_3,b_1,b_2,b_3,c_1,c_2,c_3$, sum of $a$'s is at most 1, and the same with $b$ and $c$. first inequality is $\sum_{i\neq j\neq k \in \{1,2,3\}} \frac{a_ib_jc_k}{3- b_i - c_i - a_j - c_j - a_k - b_k}\left( \frac{2}{2-b_k-c_j}+ \frac{2}{2-a_k-c_i} + \frac{2}{2-a_j-b_i}\right) \leq (a_1+a_2+a_3)(b_1+b_2+b_3)(c_1+c_2+c_3)$

The second I don't know how to show yet. I've written a program checking it for all possible configurations of numbers, and it seems like it also should be true. Still, I don't know how to get a hold on it because here i have terms once negative and once positive and thus i cannot use AM-HM anymore to split terms nicely. Can someone point me to similar inequalities that resemble the inclusion exclusion formula? Any help would be much appreciated. Here's the inequality: $1-\sum a_i -\sum b_j -\sum c_k + \sum_{i\neq j \in\{1,2,3\}} \frac{2a_ib_j}{2-b_i - a_j} + \sum_{j\neq k \in\{1,2,3\}} \frac{2b_jc_k}{2-c_j - b_k} + \sum_{i\neq k \in\{1,2,3\}} \frac{2a_ic_k}{2-c_i - a_k} - \sum_{i\neq j\neq k \in \{1,2,3\}} \frac{a_ib_jc_k}{3- b_i - c_i - a_j - c_j - a_k - b_k}\left( \frac{2}{2-b_k-c_j}+ \frac{2}{2-a_k-c_i} + \frac{2}{2-a_j-b_i}\right) \leq (1-a_1-a_2-a_3)(1-b_1-b_2-b_3)(1-c_1-c_2-c_3)$

  • $\begingroup$ Is this research or math competition? $\endgroup$ – Per Alexandersson Jun 27 '15 at 0:05
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    $\begingroup$ research. inequality comes from trying to prove negative correlation of three 0-1 random variables. I would be glad even to see some references that might resemble the second inequality. so far googling inequalities + inclusion exclusion didn't give anything that could give me a hold on this $\endgroup$ – Marek Adamczyk Jun 27 '15 at 0:09
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    $\begingroup$ If you reformulate it in terms of polynomial inequalities, this can be solved by computer algebra if I am not mistaken. $\endgroup$ – Per Alexandersson Jun 27 '15 at 1:11
  • $\begingroup$ Here is an example: en.wikipedia.org/wiki/… $\endgroup$ – Max Alekseyev Jun 27 '15 at 12:01
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    $\begingroup$ That's very interesting Per. could you point me to some resource that would outline the method? $\endgroup$ – Marek Adamczyk Jun 27 '15 at 13:58

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