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Choice, Chance and Sensible Logic
Dhamnekar Win,odd replied to Dhamnekar Win,odd's topic in Homework Help
SOLVED -
a) In how many parts, we can divide an infinite plane by n straight lines of which no two lines are parallel and no three lines are concurrent? b) In how many parts, we can divide an infinite space by n planes of which no four planes meets in a point and no two planes are parallel? How to answer both these questions? What are the answers to these questions? I am working on these questions. Any math help, problem solving hint will be accepted.
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Elements of Combinatorial Analysis
Dhamnekar Win,odd replied to Dhamnekar Win,odd's topic in Analysis and Calculus
This problem is " SOLVED" -
Elements of Combinatorial Analysis
Dhamnekar Win,odd replied to Dhamnekar Win,odd's topic in Analysis and Calculus
Thanks for your reply. I am working on the question 9 and statement in your reply to prove it practically as well as theoretically. -
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Elements of Combinatorial Analysis
Dhamnekar Win,odd replied to Dhamnekar Win,odd's topic in Homework Help
I tag this question as "SOLVED" -
So, Eventually I did it. Using formula (1) we get [math] A(4,2)= \displaystyle\sum_{k=1}^{3}\binom{4}{k}\cdot \displaystyle\sum_{v=0}^{1}(-1)^v\cdot \binom{1}{v}\cdot (1-v)^{4-k}=14[/math] Using formula (1)we get[math] A(4,3)=\displaystyle\sum_{k=1}^{2}\binom{4}{k}\cdot\displaystyle\sum_{v=0}^{2}(-1)^v\cdot \binom{2}{v} \cdot (2-v)^{4-k}=36[/math] Using formula (2) we get [math]A(4,2)=\displaystyle\sum_{v=0}^{2}(-1)^v \cdot \binom{2}{v}\cdot (2-v)^{4}=14[/math] as expected Using formula (2) we get [math] A(4,3)=\displaystyle\sum_{v=0}^{3}(-1)^v\cdot \binom{3}{v}\cdot(3-v)^{4}=36 [/math] as expected. Thanks for your guidance.
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I changed the order of summation and the expressed A(4,1+1=2)as the difference of two simple sums [math]\displaystyle\sum_{k=1}^{4}\binom{4}{k} \cdot\displaystyle\sum_{v=0}^{1}(-1)^v\cdot \binom{1}{v}\cdot(1-v)^{4-k}-\displaystyle\sum_{v=0}^{1}(-1)^v\cdot \binom{1}{v}\cdot(1-v)[/math] Now, what we can do?
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Using formula (2), we get [math] A(4,2)= \displaystyle\sum_{v=0}^{2}(-1)^v\cdot \binom{2}{v}(2-v)^4=14[/math] Using formula (1), we get [math]A(4,2)=\displaystyle\sum_{k=1}^{4} \binom{4}{k}\cdot\displaystyle\sum_{v=0}^{1}(-1)^v \binom{1}{v}(1-v)^{4-k}=15[/math] Now, how can we remove the difference of one between these two answers?
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I am trying to derive the formula (1) by combinatorial argument, but I didn't succeed. My difficulty to understand the Author's suggestions: 1) This is a classical occupancy problem. Assuming that all [math]n^r[/math] possible placements are equally probable, the probability to obtain the given occupancy numbers [math]r_1,...r_n[/math] equals [math] \frac{r!}{r_1! r_2!...r_n!} n^{-r}[/math] Here, we are concerned with only indistinguishable particles or objects. In Physics, this probability is known as Maxwell-Boltzmann statistics. Now, suppose, we have to put 4 objects in 2 cells. The number of distinguishable distributions of 4 identical objects into 2 cells is [math]\binom{3}{1}=3[/math].|***|*|, |*|***| or |**|**| But if we use formula (2) we get 14 as answer |**|**|, |**|**|, |**|**|, |**|**|, |**|**|, |**|**|, |***|*|,|***|*|,|***|*|, |***|*|, |*|***|, |*|***|, |*|***|, |*|***| . In case of A,B,C,D objects, we get |AB|CD|,|AC|BD|,|AD|BC|,|BC|AD|,|BD|AC|,|CD|AC|,|ABC|D|,|ACD|B|,|ABD|C|,|BCD|A|,|A|BCD|,|B|ACD|,|C|ABD|,|D|ABC| Using formula (1), we get [math]A(4,3)=\displaystyle\sum_{k=1}^{4}\binom{4}{k}*\displaystyle\sum_{v=0}^{2}(-1)^v*\binom{2}{v}*(2-v)^{4-k}=35[/math] I think this answer assumes distinguishable cells as well as objects. Now I don't understand , on what basis , we can say that this formula is derived assuming indistinguishable objects?