Math Is Fun Forum
  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

You are not logged in.

#1 2014-11-02 03:43:29

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,829
Website

Sum of R primes?

Problem: Given a positive integer N, determine if N can be expressed as a sum of R primes (not necessarily distinct)


'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.

Offline

#2 2014-11-02 05:41:45

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Sum of R primes?

It is related to Goldbach?


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

#3 2014-11-02 12:04:48

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,829
Website

Re: Sum of R primes?

I thought it is not but they say that we can use the Goldbach to solve it in O(n)


'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.

Offline

#4 2014-11-02 12:06:03

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Sum of R primes?

An algorithm?


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

#5 2014-11-02 12:06:38

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,829
Website

Re: Sum of R primes?

I beg your pardon?


'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.

Offline

#6 2014-11-02 12:07:14

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Sum of R primes?

There is an algorithm for the problem?


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

#7 2014-11-02 12:11:00

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,829
Website

Re: Sum of R primes?

You misunderstood the question. The challenge is to find an algorithm.


'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.

Offline

#8 2014-11-02 12:12:58

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Sum of R primes?

It is easy to see that you can always decompose a number into a sum of primes.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

#9 2014-11-02 12:19:58

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,829
Website

Re: Sum of R primes?


'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.

Offline

#10 2014-11-02 12:21:36

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Sum of R primes?

Do they know about R = 2?


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

#11 2014-11-02 12:31:13

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,829
Website

Re: Sum of R primes?

How does it matter?


'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.

Offline

#12 2014-11-02 12:32:41

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Sum of R primes?

It is not known whether it can be done for R = 2 so what sense is the algorithm?


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

#13 2014-11-02 12:40:42

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,829
Website

Re: Sum of R primes?

The algorithm is supposed to be finding whether it can be done for a given R and N


'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.

Offline

#14 2014-11-02 12:42:58

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Sum of R primes?

Supposing R is 2? It is not known whether any number bigger than 2 can always be decomposed into the sum of 2 primes.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

#15 2014-11-02 12:44:49

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,829
Website

Re: Sum of R primes?

We are not talking about any number. You need to find an algorithm to determine if a given number  N  is a sum of R primes.


'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.

Offline

#16 2014-11-02 12:48:45

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Sum of R primes?

Every even integer greater than 2 can be expressed as the sum of two primes.

That is the Goldbach conjecture, we do not know if it is true.

What is R? If it is an argument of your function it had better not be equal to 2.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

#17 2014-11-02 12:50:03

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,829
Website

Re: Sum of R primes?

You still do not understand. Why not read their page?


'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.

Offline

#18 2014-11-02 12:55:41

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Sum of R primes?

I can not even see their page for one thing and I am talking with you.

If I ask you to break 1982763541552611119981001825123289617 into the sum of two primes it just might not be possible because the Goldbach conjecture might be false. Are you aware of any algorithm that would spit out false and therefore make history by disproving the Goldbach conjecture?


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

#19 2014-11-02 19:50:30

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,829
Website

Re: Sum of R primes?

It is not an even number.

Okay, here are some constraints.

1 <= N <= 10^12
1 <= R <= 10^12

Last edited by Agnishom (2014-11-02 19:58:30)


'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.

Offline

#20 2014-11-02 20:24:23

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Sum of R primes?

That is much better it is valid to 4 x 10^18 for sure.

So what is the problem, write the code.


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

#21 2014-11-02 20:30:39

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,829
Website

Re: Sum of R primes?

I have a dynamic programming code


'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.

Offline

#22 2014-11-02 20:32:58

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Sum of R primes?

What language? What are their requirements?


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

#23 2014-11-03 00:28:25

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,829
Website

Re: Sum of R primes?

There are many options but I like python


'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.

Offline

#24 2014-11-03 04:44:26

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

Re: Sum of R primes?

What have you done?


In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

Offline

#25 2014-11-03 05:10:42

Agnishom
Real Member
From: Riemann Sphere
Registered: 2011-01-29
Posts: 24,829
Website

Re: Sum of R primes?

I'll try to do the same thing in M


'And fun? If maths is fun, then getting a tooth extraction is fun. A viral infection is fun. Rabies shots are fun.'
'God exists because Mathematics is consistent, and the devil exists because we cannot prove it'
I'm not crazy, my mother had me tested.

Offline

Board footer

Powered by FluxBB