Are These Rules new Conjectures in Set Theory?

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Discussion Overview

The discussion revolves around proposed rules in set theory, specifically concerning the calculation of subsets and their sums. Participants explore whether these rules represent new conjectures in mathematics or if they are already established concepts within combinatorics and set theory.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Exploratory

Main Points Raised

  • One participant presents two rules related to subsets and their sums, using binomial coefficients to calculate the number of subsets with a specific number of members.
  • Another participant argues that the discussion is more aligned with combinatorics than set theory, emphasizing the need for clearer definitions and established set operations.
  • Some participants assert that Rule 1 is well-known and documented in combinatorial mathematics, referencing binomial coefficients and the properties of power sets.
  • There is a challenge regarding the clarity of the definitions used for set B, with calls for more precise enumeration without ellipses.
  • One participant expresses a desire for academic references to support claims made about the rules, indicating skepticism about the reliability of Wikipedia as a source.
  • Another participant provides links to academic papers as references for the established nature of the discussed rules.
  • The conversation includes a personal anecdote about applying these rules to accounting control, suggesting practical implications of the mathematical concepts discussed.

Areas of Agreement / Disagreement

Participants do not reach a consensus. There is disagreement about whether the proposed rules are new conjectures or established results in mathematics, with some asserting they are known while others seek clarification and further validation.

Contextual Notes

There are limitations in the clarity of definitions provided, particularly regarding the construction of set B and the use of ellipses in enumeration. The discussion also reflects varying levels of familiarity with combinatorial concepts and the need for precise mathematical language.

Gh. Soleimani
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We can easily find out below rules in set theory:

1. Let consider set “A” as follows:

A = {a1, a2, a3, a4… an} and also power set of A is set C:

C = {{}, {a1}, {a2}, {a3}, {a4}, {a1, a2}, {a1, a3},….{an}}

Rule 1: To find the number of subsets with precise members number, we can use Binomial Coefficient

C (n, r) = n! / r! (n-r)!


Where:

n = number of members in set A

r = number of precise member for each subset

Example:

We have set A = {1, 2, 3, 4, 5, 6, 7}

The number of subsets with no member is: C (7, 0) = 1

The number of subsets with one member is: C (7, 1) = 7

The number of subsets with two member is: C (7, 2) = 21

The number of subsets with three member is: C (7, 3) = 35

The number of subsets with four member is: C (7, 4) = 35

The number of subsets with five member is: C (7, 5) = 21

The number of subsets with six member is: C (7, 3) = 7

The number of subsets with seven member is: C (7, 3) = 1

2. Let consider set “A” and power set of A which is set “C” as follows:

A = {a1, a2, a3, a4… an}

C = {{}, {a1}, {a2}, {a3}, {a4}, {a1, a2}, {a1, a3},….{an}}

We can find set “B” below cited:

B = {x, y, z, t,…..}

Where:

x, y, z, t,… = functions of internal sum of each subset

For instance, x = a1, z = a1 + a2, t = a1 + a2 + a3 and ……..

Rule 2: If SB = total Sum of members of set B and SA = total sum of members of set A, we will have:

SB / SA = 2^ (n-1) , n = number of members set A

Example:

Assume, we have:

A = {1, 2, 3, 4} then

C = {{}, {1}, {2}, {3}, {4}, {1,2}, {1,3}, {1,4}, {2,3}, {2,4}, {3,4}, {1,2,3}, {1,2,4}, {1,3,4}, {2,3,4}, {1,2,3,4}}

SB = 0+1+2+3+4+3+4+5+5+6+7+6+7+8+9+10 = 80

SA = 1+2+3+4 = 10

SB / SA = 2^ (n-1) = 2 ^ (4-1) = 80 /10

Now, the questions is:

- Are these rules new ones in Set Theory?

- Are These Rules new Conjectures in Mathematics?
 
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What you are doing looks more like Combinatorics that Set Theory.
Gh. Soleimani said:
We can find set “B” below cited:

B = {x, y, z, t,…..}

Where:

x, y, z, t,… = functions of internal sum of each subset

For instance, x = a1, z = a1 + a2, t = a1 + a2 + a3 and ……..
This needs to be explained better, because it's not at all clear what you intend B to be. You can't define a set with a 'for instance'. You need to define it using recognised, unambiguous set operations such as powerset, union, intersection, complementation or filtering on a logical criterion. Enumeration (listing elements) is fine, as long as it's completely clear what the elements are, but it's not OK if you use ellipses (the '...' symbol) as you have above. Enumeration has to be complete, with no ellipses and no 'etc'.
 
andrewkirk said:
What you are doing looks more like Combinatorics that Set Theory.

This needs to be explained better, because it's not at all clear what you intend B to be. You can't define a set with a 'for instance'. You need to define it using recognised, unambiguous set operations such as powerset, union, intersection, complementation or filtering on a logical criterion. Enumeration (listing elements) is fine, as long as it's completely clear what the elements are, but it's not OK if you use ellipses (the '...' symbol) as you have above. Enumeration has to be complete, with no ellipses and no 'etc'.
Sorry, it is not the answer to my questions.
 
Samy_A said:
No.

Rule 1 is well known (https://en.wikipedia.org/wiki/Binomial_coefficient#Combinatorics_and_statistics)
Rule 2 (if I interpreted it correctly, @andrewkirk correctly stated that you are not very clear there), is a consequence of the well known result that the power set of a set with ##n## elements has ##2^n## elements (https://en.wikipedia.org/wiki/Power_set#Properties).

Please care again on rule1. Your answer is completely wrong. I say to you a problem: How can we find the number of subsets with precise members number? The solution is, to use Binomial Coefficient. For instance, if we have a set with 7 members, The number of subsets with four member will be 35. Have you any anouther solution for this problem? or Have you another reference which shows us this solution for this problem?
 
Gh. Soleimani said:
Please care again on rule1. Your answer is completely wrong.
Samy_A was responding to what he thought you meant. What you stated was not clear, especially the part "with precise members number":
Rule 1: To find the number of subsets with precise members number, we can use Binomial Coefficient
The binomial coefficients give the sizes of each of the subsets of a certain size.
Gh. Soleimani said:
I say to you a problem: How can we find the number of subsets with precise members number? The solution is, to use Binomial Coefficient.
Which is what Samy_A was saying.
Gh. Soleimani said:
For instance, if we have a set with 7 members, The number of subsets with four member will be 35. Have you any anouther solution for this problem? or Have you another reference which shows us this solution for this problem?
 
Mark44 said:
Samy_A was responding to what he thought you meant. What you stated was not clear, especially the part "with precise members number":

The binomial coefficients give the sizes of each of the subsets of a certain size.
Which is what Samy_A was saying.

Thank you for your reply. But I did not see your quote (The binomial coefficients give the sizes of each of the subsets of a certain size) on this link: https://en.wikipedia.org/wiki/Binomial_coefficient#Combinatorics_and_statistics whereas, I need to have official reference (academic reference) because I am willing to know if your quote had been already proved or it is a conjecture. In the meanwhile, please be informed that wikipedia is not a reference because each moment its content has been edited.
 
Gh. Soleimani said:
Thank you for your reply. But I did not see your quote (The binomial coefficients give the sizes of each of the subsets of a certain size) on this link: https://en.wikipedia.org/wiki/Binomial_coefficient#Combinatorics_and_statistics
It's in that section that Samy_A cited. For your example, with a set with 7 elements, the number of subsets with 4 elements is ##\binom{7}{4}## = 35.

If you have a set with n elements, the number of subsets with exactly k elements is ##\binom{n}{k} = \frac{n!}{k!(n - k)!}##.
Gh. Soleimani said:
whereas, I need to have official reference (academic reference) because I am willing to know if your quote had been already proved or it is a conjecture. In the meanwhile, please be informed that wikipedia is not a reference because each moment its content has been edited.
These formulas for the binomial coefficients have been around for a long time, and are very well known. Any textbook on combinatorics or probability will have this formula.
 
Mark44 said:
It's in that section that Samy_A cited. For your example, with a set with 7 elements, the number of subsets with 4 elements is ##\binom{7}{4}## = 35.

If you have a set with n elements, the number of subsets with exactly k elements is ##\binom{n}{k} = \frac{n!}{k!(n - k)!}##.

These formulas for the binomial coefficients have been around for a long time, and are very well known. Any textbook on combinatorics or probability will have this formula.
Yes. Thank you. I found the proof of rule 1 on below papers:
http://www.maths.qmul.ac.uk/~pjc/notes/comb.pdf
http://math.mit.edu/~rstan/ec/ec1.pdf
 
  • #10
Let me tell you that the basic of above rules returns back to my case of accounting control such as below example:
Consider: Set A = {a1, a2, a3, a4,...} and set B = {b1, b2, b3, b4,...]
Now,we want to know: which total sum of 1 or 2 or 3 or more of members of set A are just equal to total sum of 1 or 2 or 3 or more of members of set B? For instance,
a1 = b2+b3+b4+b5 or a2+a3+a7+a12 = b2+b3 and etc. How can we find all equilibriums?
I solved this case by using of a idea of power set and posted my solution on my website. Do you have any another idea to solve this case?
 
  • #11
Gh. Soleimani said:
Rule 2: If SB = total Sum of members of set B and SA = total sum of members of set A, we will have:
SB / SA = 2^ (n-1) , n = number of members set A
Your rule doesn't work.
Counterexample :
Let A = {1, 2}
P(A) = { {}, 1, 2, {1, 2}}
Let B = { 2, 3, 5, 6}
P(B) = { {}, 2, 3, 5, 6, {2, 3}, {2, 5}, {2, 6}, {3, 5}, {3, 6}, {5, 6}, {2, 3, 5}, {2, 3, 6}, {2, 5, 6}, {3, 5, 6}, {2, 3, 5, 6}}
##\sum{P(B}## =128

##\sum{P(A}## = 1 + 2 + 3 = 6
##\frac{\sum{P(B}}{\sum{P(A}} = \frac{128}{6} \approx 21.33##. This is not a power of 2 for any integer n.
 
  • #12
It's not very clear what rule 2 exactly means.

My interpretation was as follows:
A is a finite set of integers with n elements. SA is the sum of all elements of A.
C is the power set of A.
Now, for each element of C one can compute the sum of its elements: these sums are the element of the set (actually the multiset) B.
SB is the sum of all elements of B.

Rule 2 states than SB=SA*##2^{(n-1)}##
I think that with this interpretation the rule is correct, but quite elementary.
As every element of A will be an element of exactly ##2^{(n-1)}## subsets of A, it is rather obvious that SB=SA*##2^{(n-1)}##
 
  • #13
Mark 44: Your way to get elements of B in your counterexmample is wrong. Because, we will have 0, 1, 2 and 3 for B then SB = 6 and SA = 3 , SB/SA = 2 = 2 ^ 2 -1
Samy A: you got true concept of this rule. Do you have any proof for this rule or it is a conjecture?
 
  • #14
Gh. Soleimani said:
Mark 44: Your way to get elements of B in your counterexmample is wrong.
No, it is not wrong. You have not specified that the sets have to be consecutive integers starting with 1.
Rule 2 just mentions two sets A and B, and doesn't put any further restrictions on them.
It's up to you to provide more conditions.
Gh. Soleimani said:
Because, we will have 0, 1, 2 and 3 for B then SB = 6 and SA = 3 , SB/SA = 2 = 2 ^ 2 -1
Samy A: you got true concept of this rule. Do you have any proof for this rule or it is a conjecture?
 
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  • #15
Gh. Soleimani said:
Mark 44: Your way to get elements of B in your counterexmample is wrong. Because, we will have 0, 1, 2 and 3 for B then SB = 6 and SA = 3 , SB/SA = 2 = 2 ^ 2 -1
It is up to you to be clear. I was "lucky" in guessing what you meant with rule 2, mainly because I worked backward from the result.
Gh. Soleimani said:
Samy A: you got true concept of this rule. Do you have any proof for this rule or it is a conjecture?
I already stated the "proof":
Samy_A said:
As every element of A will be an element of exactly ##2^{(n-1)}## subsets of A, it is rather obvious that SB=SA*##2^{(n-1)}##
This is just a consequence of the well known result that the power set of a set with m elements has ##
2^{m}
## elements, applied to m=n-1. (As already stated in my first post in this thread, by the way.)
 
  • #16
I deleted rule 1 and edited rule 2 and also added new rule (rule 3) as follows:

1. Let consider set “A” and power set of A which is set “C” as follows:

A = {a1, a2, a3, a4… an}

C = {{}, {a1}, {a2}, {a3}, {a4}, {a1, a2}, {a1, a3},….{an}}

We can find set “B” in which each member of set B is generated by adding members of each subset of power set C below cited:

B = {{}, {a1}, {a2}, {a3}, {a4}, {a1+ a2}, {a1 + a3}, {a2 + a3 + a4)….{an}}Rule 1: If SB = total Sum of members of set B and SA = total sum of members of set A, we will have:

SB / SA = 2^ (n-1) , n = number of members set A

Example:

Assume, we have:

A = {1, 2, 3, 4} then

C = {{}, {1}, {2}, {3}, {4}, {1,2}, {1,3}, {1,4}, {2,3}, {2,4}, {3,4}, {1,2,3}, {1,2,4}, {1,3,4}, {2,3,4}, {1,2,3,4}}

B = {{}, {1}, {2}, {3}, {4}, {1+2}, {1+3}, {1+4}, {2+3}, {2+4}, {3+4}, {1+2+3}, {1+2+4}, {1+3+4}, {2+3+4}, {1+2+3+4}}

SB = 0+1+2+3+4+3+4+5+5+6+7+6+7+8+9+10 = 80

SA = 1+2+3+4 = 10

SB / SA = 2^ (n-1) = 2 ^ (4-1) = 80 /10 2. Let consider set “A” and power set of A which is set “C” as follows:

A = {a1, a2, a3, a4… an}

C = {{}, {a1}, {a2}, {a3}, {a4}, {a1, a2}, {a1, a3},….{an}}

We can find set “B” in which each member of set B is generated by multiplying members of each subset of power set C below cited:

B = {{}, {a1}, {a2}, {a3}, {a4}, {a1* a2}, {a1*a3}, {a2*a3*a4)….{an}}

Rule 2: If SB = total Sum of members of set B and SA = total sum of members of set A, we will have:

(SB+ 1)/ SA = 2n!/n , n = number of members set A

Or SB = [(2n!/n)*SA] - 1

Example:

Assume, we have:

A = {1, 2, 3, 4} then

C = {{}, {1}, {2}, {3}, {4}, {1,2}, {1,3}, {1,4}, {2,3}, {2,4}, {3,4}, {1,2,3}, {1,2,4}, {1,3,4}, {2,3,4}, {1,2,3,4}}

B = {{}, {1}, {2}, {3}, {4}, {1*2}, {1*3}, {1*4}, {2*3}, {2*4}, {3*4}, {1*2*3}, {1*2*4}, {1*3*4}, {2*3*4}, {1*2*3*4}}

SA = 1+2+3+4 = 10 , SB = 1+2+3+4+2+3+4+6+8+12+6+8+12+24+24 =119

(SB +1) / SA = (2*(1*2*3*4)/4) = 12 = (119 +1)/10 Now, the questions is:

- Are these rules new ones in Set Theory?

- Are These Rules new Conjectures in Mathematics?
 
  • #17
Gh. Soleimani said:
Now, the questions is:

- Are these rules new ones in Set Theory?

- Are These Rules new Conjectures in Mathematics?
You have already been shown that Rule 1 (your former Rule 2) is a trivial consequence of an elementary fact about power sets.

Rule 2 is wrong without further conditions on A.
Example:
n=2
A={2,5}
SA=7
C={{},{2},{5},{2,5}}
B={0,2,5,10}
SB=17
(SB+ 1)/ SA =18/7
2n!/2=2
 
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  • #18
Yes. You are true.
A = a set of Natural number
Of Course, I do not consider zero as Natural number. I will say it Whole number if we consider zero.
 
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  • #19
Gh. Soleimani said:
Yes. You are true.
A = a set of Natural number
Of Course, I do not consider zero as Natural number. I will say it Whole number if we consider zero.
My counterexample A={2,5} is a set of natural numbers, and doesn't contain 0. So your new rule 2 is still wrong.
 
  • #20
I did not tell you that A is a subset of natural number. It is ok. Let us consider N instead of A. It means that set of natural number. and then we have:
(SB+1) / SN = 2n!/n
 
  • #21
Gh. Soleimani said:
I did not tell you that A is a subset of natural number. It is ok. Let us consider N instead of A. It means that set of natural number. and then we have:
(SB+1) / SN = 2n!/n
Can you please state clearly the conditions that the set A (or whatever you want to call it, the name of the set is irrelevant) has to satisfy in order for your rule 2 to be valid?

Clearly rule 2 is not valid for the set {2,5}.

If you don't state all the conditions for your rule 2 clearly, it is meaningless.
 
  • #22
please wait. I am busy now
 
  • #23
Samy_A said:
Can you please state clearly the conditions that the set A (or whatever you want to call it, the name of the set is irrelevant) has to satisfy in order for your rule 2 to be valid?

Clearly rule 2 is not valid for the set {2,5}.

If you don't state all the conditions for your rule 2 clearly, it is meaningless.
I agree completely. If we decide to try your (Gh. Soleimani) rule on, say A = {1, 3, 5} and B = {2}, and find that it doesn't work, you can't come back and tell us we are wrong. As Samy_A said, if you don't specify clearly any and all conditions on the sets involved, the rules are meaningless.
 
  • #24
I edited my article and my assumtions as follows:

2. Let consider A as set of Arithmetic Progression where:

d = 1, a1 = 1 and an = a1 + (n - 1)d, n = 1, 2, 3,…..

In this case, we have:

A = {a1, (a1+1), (a2 +1),……. (a1 + (n - 1)d)}

And power set of A which is set “C” as follows:

C = {{}, {a1}, {a2}, {a3}, {a4}, {a1, a2}, {a1, a3},….{an}}

We can find set “B” in which each member of set B is generated by multiplying members of each subset of power set C below cited:

B = {{}, {a1}, {a2}, {a3}, {a4}, {a1* a2}, {a1*a3}, {a2*a3*a4)….{an}}

Rule 2: If SB = total Sum of members of set B and SA = total sum of members of set A, we will have:

(SB+ 1)/ SA = 2n!/n , n = number of members set A

Or SB = [(2n!/n)*SA] - 1

Example:

Assume, we have:

A = {1, 2, 3, 4} then

C = {{}, {1}, {2}, {3}, {4}, {1,2}, {1,3}, {1,4}, {2,3}, {2,4}, {3,4}, {1,2,3}, {1,2,4}, {1,3,4}, {2,3,4}, {1,2,3,4}}

B = {{}, {1}, {2}, {3}, {4}, {1*2}, {1*3}, {1*4}, {2*3}, {2*4}, {3*4}, {1*2*3}, {1*2*4}, {1*3*4}, {2*3*4}, {1*2*3*4}}

SA = 1+2+3+4 = 10 , SB = 1+2+3+4+2+3+4+6+8+12+6+8+12+24+24 =119

(SB +1) / SA = (2*(1*2*3*4)/4) = 12 = (119 +1)/10Now, the questions is:

- Are these rules new ones in Set Theory?

- Are These Rules new Conjectures in Mathematics?
 
  • #25
Gh. Soleimani said:
I edited my article and my assumtions as follows:

2. Let consider A as set of Arithmetic Progression where:

d = 1, a1 = 1 and an = a1 + (n - 1)d, n = 1, 2, 3,…..

In this case, we have:

A = {a1, (a1+1), (a2 +1),……. (a1 + (n - 1)d)}

And power set of A which is set “C” as follows:

C = {{}, {a1}, {a2}, {a3}, {a4}, {a1, a2}, {a1, a3},….{an}}

We can find set “B” in which each member of set B is generated by multiplying members of each subset of power set C below cited:

B = {{}, {a1}, {a2}, {a3}, {a4}, {a1* a2}, {a1*a3}, {a2*a3*a4)….{an}}

Rule 2: If SB = total Sum of members of set B and SA = total sum of members of set A, we will have:

(SB+ 1)/ SA = 2n!/n , n = number of members set A

Or SB = [(2n!/n)*SA] - 1

Example:

Assume, we have:

A = {1, 2, 3, 4} then

C = {{}, {1}, {2}, {3}, {4}, {1,2}, {1,3}, {1,4}, {2,3}, {2,4}, {3,4}, {1,2,3}, {1,2,4}, {1,3,4}, {2,3,4}, {1,2,3,4}}

B = {{}, {1}, {2}, {3}, {4}, {1*2}, {1*3}, {1*4}, {2*3}, {2*4}, {3*4}, {1*2*3}, {1*2*4}, {1*3*4}, {2*3*4}, {1*2*3*4}}

SA = 1+2+3+4 = 10 , SB = 1+2+3+4+2+3+4+6+8+12+6+8+12+24+24 =119

(SB +1) / SA = (2*(1*2*3*4)/4) = 12 = (119 +1)/10Now, the questions is:

- Are these rules new ones in Set Theory?

- Are These Rules new Conjectures in Mathematics?
Thanks.

Let's simplify this for starters.
For a given n, A is simply the set of all integers from 1 to n: A={1,2,...,n}
So, SA=n(n+1)/2

Your rule then simplifies to ##SB=\frac{2n!}{n}*\frac{n(n+1)}{2} - 1=n!(n+1)-1=(n+1)!-1##

So, for a given n, the rule states: SB=(n+1)!-1

I'm not immediately aware of this rule being known (someone else may be, of course), but it can be proven easily. I did it by mathematical induction, by the way.
 
  • #26
Thank you to simply this rule. Then you say that this rule is not a conjecture.
 
  • #27
Gh. Soleimani said:
Thank you to simply this rule. Then you say that this rule is not a conjecture.
A conjecture is a mathematical statement for which no proof is known. Fermat's Last Theorem was a conjecture for centuries, but now is a (proven) theorem.
Your rule is not a conjecture, as it can be proven.
Whether it is new or not, whether it is useful or not, I can't really say.
 
  • #28
I think the last conjecture is referred to Beal Conjecture and I remember AMS awarded $1000000 prize for someone who presented a proof or counterexample.
Anyway, here is another new rule:3. Let consider set “A” as subset of R and power set of A which is set “C” as follows:
A ⊂ R
C = {{}, {a1}, {a2}, {a3}, {a4}, {a1, a2}, {a1, a3},….{an}}

We can find set “B” in which each member of set B is generated by average of members of each subset of power set C below cited:

B = {{}, {a1}, {a2}, {a3}, {a4}, {(a1+ a2)/2}, {(a1 + a3)/2}, {(a2 + a3 + a4)/3}….{an}}Rule 3: If SB = total Sum of members of set B:

Then: SB = ((2^n)-1)*Average (A) , n = number of members set A

Example:

Assume, we have:

A = {1, 2, 3, 4} then

C = {{}, {1}, {2}, {3}, {4}, {1,2}, {1,3}, {1,4}, {2,3}, {2,4}, {3,4}, {1,2,3}, {1,2,4}, {1,3,4}, {2,3,4}, {1,2,3,4}}

B = {{}, {1}, {2}, {3}, {4}, {(1+2)/2}, {(1+3)/2}, {(1+4)/2}, {(2+3)/2}, {(2+4)/2}, {(3+4)/2}, {(1+2+3)/3}, {(1+2+4)3}, {(1+3+4)/3}, {(2+3+4)/3}, {(1+2+3+4)/4}

SB = 0+1+2+3+4+1.5+2+2.5+2.5+3+3.5+2+2.333333+2.6666666+3+2.5 = 37.5

Average (A) = (1+2+3+4)/4 = 2.5

SB = ((2^ 4) -1)*2.5 = 37.5
 
  • #29
Gh. Soleimani said:
I think the last conjecture is referred to Beal Conjecture and I remember AMS awarded $1000000 prize for someone who presented a proof or counterexample.
I don't understand what all this has to do with Beal's conjecture.
Gh. Soleimani said:
Anyway, here is another new rule:3. Let consider set “A” as subset of R and power set of A which is set “C” as follows:
A ⊂ R
C = {{}, {a1}, {a2}, {a3}, {a4}, {a1, a2}, {a1, a3},….{an}}

We can find set “B” in which each member of set B is generated by average of members of each subset of power set C below cited:

B = {{}, {a1}, {a2}, {a3}, {a4}, {(a1+ a2)/2}, {(a1 + a3)/2}, {(a2 + a3 + a4)/3}….{an}}Rule 3: If SB = total Sum of members of set B:

Then: SB = ((2^n)-1)*Average (A) , n = number of members set A

Example:

Assume, we have:

A = {1, 2, 3, 4} then

C = {{}, {1}, {2}, {3}, {4}, {1,2}, {1,3}, {1,4}, {2,3}, {2,4}, {3,4}, {1,2,3}, {1,2,4}, {1,3,4}, {2,3,4}, {1,2,3,4}}

B = {{}, {1}, {2}, {3}, {4}, {(1+2)/2}, {(1+3)/2}, {(1+4)/2}, {(2+3)/2}, {(2+4)/2}, {(3+4)/2}, {(1+2+3)/3}, {(1+2+4)3}, {(1+3+4)/3}, {(2+3+4)/3}, {(1+2+3+4)/4}

SB = 0+1+2+3+4+1.5+2+2.5+2.5+3+3.5+2+2.333333+2.6666666+3+2.5 = 37.5

Average (A) = (1+2+3+4)/4 = 2.5

SB = ((2^ 4) -1)*2.5 = 37.5
Nice one.

The proof is straightforward using the well known identity ##\sum_{k=0}^n \binom{n}{k}=2^n##.
 
  • #30
The Beal Conjecture states that the only solutions to the equation A^x + B^y = C^z, when A, B and C are positive integers, and x, y and z are positive integers greater than two, are those in which A, B and C have a common factor. The American Mathematical Society in Providence, Rhode Island, said that typical of many statements in number theory, they're "easy to say but extremely difficult to prove.” The Beal Prize is funded by D. Andrew Beal, a prominent banker who is also a mathematics enthusiast. An AMS-appointed committee, the Beal Prize Committee, will recommend awarding this prize for either a proof or a counterexample of the Beal Conjecture published in a refereed and respected mathematics publication. The prize money—now US$1,000,000—is being held by the AMS until it is awarded. The spendable income from investment of the prize money is used to fund the annual Erdős Memorial Lecture and other activities of the Society that benefit early-career mathematicians.

A valid counterexample needs to satisfy all four conditions—don't leave one out:

A,B,C,x,y,z are positive integers
x,y,z>2
A^x+B^y=C^z
A
,B,C have no common prime factor.
 

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