Galois Groups for a system of Linear equations?

In summary, the conversation discusses the use of Galois theory and/or number theory to solve a system of multiple equations in the form αx+βy+ζz=p_{1}, where α,β,ζ are constants, x,y,z are variables, and p is a prime. The other equations in the system can all be written in the form α_{i}x_{i}+β_{i}y_{i}+ζ_{i}z_{i}=p_{i}, with different primes and constants. The main interest is in solving the problem in the field \textbf{Z}/n\textbf{Z}, for integers less than n. The conversation suggests using arithmetic mod n to
  • #1
joebohr
57
0
If I were to solve a system of multiple equations in the form
αx+βy+ζz=p[itex]_{1}[/itex]
Where α,β,ζ are constants x,y,z are variables, and p is a prime, how would I use Galois theory and/or number theory to find the number of solutions if the other equations could all be written in the form

α[itex]_{i}[/itex]x[itex]_{i}[/itex]+β[itex]_{i}[/itex]y[itex]_{i}[/itex]+ζ[itex]_{i}[/itex]z[itex]_{i}[/itex]=p[itex]_{i}[/itex] where, once again, each α,β,ζ are constants, each p is a distinct prime, and x,y,z are all variables?

Thanks in advance.
 
Physics news on Phys.org
  • #2
You should clarify two points.

1. Are you dealing with an applied math situation where the coefficients of your equation are approximate values, such as measured temperatures etc. I don't think Galois theory (at least as it is currently practiced) is useful in such a situation. It depends on exact numerical relations.

2. Is your main interest in solving a particular problem or are you simply trying to understand Galois theory? (I won't be of much help in the latter case!)
 
  • #3
Stephen Tashi said:
You should clarify two points.

1. Are you dealing with an applied math situation where the coefficients of your equation are approximate values, such as measured temperatures etc. I don't think Galois theory (at least as it is currently practiced) is useful in such a situation. It depends on exact numerical relations.

2. Is your main interest in solving a particular problem or are you simply trying to understand Galois theory? (I won't be of much help in the latter case!)

Thanks for asking for clarification, I didn't think my question was very clear.

First off, I am not dealing with an applied problem or any particular problem with approximate coefficients. Secondly, I want to know how to use Galois Theory and/or Number Theory to solve a particular class of problems (namely linear systems of 2 or 3 variables where the sum of each variable multiplied by a certain coefficient equals a prime). I am not concerned with what the solutions are, but I though since the type of problem lends itself to number theory and permutation groups, that Galois Theory would help determine the number of solutions.
 
  • #4
The topics of primes and number theory suggest that you might be interested in the integer solutions to such equations. Is that the case? Or are you trying to count the number of solutions that involve any real numbers?
 
  • #5
Stephen Tashi said:
The topics of primes and number theory suggest that you might be interested in the integer solutions to such equations. Is that the case? Or are you trying to count the number of solutions that involve any real numbers?

Yes, of course, I should have mentioned that. I am looking for the process of solving this problem in the field [itex]\textbf{Z}[/itex]/n[itex]\textbf{Z}[/itex]. That is, I am trying to figure out how to solve this problem generally for integers less than an integer n.
 
  • #6
joebohr said:
the field [itex]\textbf{Z}[/itex]/n[itex]\textbf{Z}[/itex].
So we assume n is a prime number.

That is, I am trying to figure out how to solve this problem generally for integers less than an integer n.

Technically, that's not the same as solving in terms of residue classes of integers mod n, but I'll assume that's what you meant.

The only suggestion I have is use the usual way of operating on simultaneous equations (using arithmetic mod n) to eliminate as many variables as possible, so that you end up with a single equation in one or more unknowns. I think there is a well developed theory of solving a single linear congruence in several unknowns. I don't know that theory by memory. I'd have to look it up.

It isn't clear what kind of answer you want. Are you looking for some theorem that is more sweeping and abstract? I suggest you formulate your question precisely and post it in the forum section on number theory. (The usual application of Galois theory deals with the solution of polynomial equations in a single unknown. I'm not familiar with generalization of the idea to situations involving several variables. Any forum member who is, is welcome to chime in.)
 
  • #7
Stephen Tashi said:
So we assume n is a prime number.

Didn't mean to imply that, the only primes are p, n just determines what solutions x such that x<n-1 we are concerned with. If you want a specific problem, say n=12.

Stephen Tashi said:
Technically, that's not the same as solving in terms of residue classes of integers mod n, but I'll assume that's what you meant.

I did not intend to suggest that we were working with residue classes. I know that is how it could be written and is not technically the same, but I did not mean for residue classes to have any special significance. You could consider it (for n=12) to be all of the integers mod 12, which allows for extra solutions, but I am only concerned with those that are equal to or less than 11.

Stephen Tashi said:
The only suggestion I have is use the usual way of operating on simultaneous equations (using arithmetic mod n) to eliminate as many variables as possible, so that you end up with a single equation in one or more unknowns. I think there is a well developed theory of solving a single linear congruence in several unknowns. I don't know that theory by memory. I'd have to look it up.

It isn't clear what kind of answer you want. Are you looking for some theorem that is more sweeping and abstract? I suggest you formulate your question precisely and post it in the forum section on number theory. (The usual application of Galois theory deals with the solution of polynomial equations in a single unknown. I'm not familiar with generalization of the idea to situations involving several variables. Any forum member who is, is welcome to chime in.)

I had this idea earlier, but then the equation would be in the form α[itex]_{1}[/itex]a+f=0

Where a is a variable, α[itex]_{1}[/itex] a constant, and f is a function of the different primes. This seems to be solvable by Galois theory. I got this far but I didn't know what to do with the function f(p[itex]_{i}[/itex]). I'd like a general result but maybe I could try factoring mod c and solving for c over the primes. But then how would I factor a system mod c in the primes?

Maybe the question would be more illustrative if I gave a numerical example of what I was trying to solve:

3a+2b+c=p[itex]_{1}[/itex]
2a+b+5c=p[itex]_{2}[/itex]
3c-b=p[itex]_{3}[/itex]

Where p[itex]_{i}[/itex] are all primes [not necessarily prime ideals] and a,b,c are less than 12. I just made up this problem to see if anyone could explain the process; I'm interested in how I would apply this process to any of the original class of problems (using Galois Theory or Abstract A.gebra), not with the actual solution.
 
Last edited:
  • #8
joebohr said:
3a+2b+c=p[itex]_{1}[/itex]
2a+b+5c=p[itex]_{2}[/itex]
3c-b=p[itex]_{3}[/itex]

Where p[itex]_{i}[/itex] are all primes [not necessarily prime ideals] and a,b,c are less than 12.


OK, I understand your example. You have equations (=) instead of congruences ([itex] \equiv [/itex] mod n). You're seeking non-negative integer solutions for a,b,c that are each less than 12 in the example, correct?

At the moment, I don't see how number theory adds any knowledge to the solution of the problem that isn't already present in the ordinary theory of solving simultaneous linear equations.

If the determinant of the coefficients is not zero, the equations have a unique solution and either it meets your requirements or it doesn't.

A more interesting case is when there are infinitely many solutions. Then they are a subset of [itex]R^3 [/itex]. What does this space look like? I suppose the usual way to write it is to let [itex] (a_0,b_0,c_0) [/itex] be one particular solution to the equations. Then each solution can be written as [itex] (a_0,b_0,c_0) + v [/itex] where [itex] v [/itex] is a solution to the homogenous equations

3a+2b+c=0
2a+b+5c=0
3c-b=0

The set of solutions looks like a vector subspace of [itex] R^3 [/itex] that has been translated away from the origin by adding the vector [itex] (a_0,b_0,c_0) [/itex] to each of its points. To get an answer that meets your requirements, you must determine if that set contains some member of a lattice of points.

Determining the answer to that might involve some number theory, but I'm still not sure if that's the kind of thing you have in mind.

If you were thinking about applying group theory to the problem, I assume you were thinking about permutation groups What things were you going to permute with the permutations?
 
  • #9
Stephen Tashi said:
OK, I understand your example. You have equations (=) instead of congruences ([itex] \equiv [/itex] mod n). You're seeking non-negative integer solutions for a,b,c that are each less than 12 in the example, correct?
Yes, but you could easily introduce number theory by writing the specific cases and finding the number of solutions to the equations
3a+2b+c=([itex] \equiv [/itex]1 mod 4)
2a+b+5c=([itex] \equiv [/itex]1 mod 4)
3c-b=([itex] \equiv [/itex]1 mod 4)
3a+2b+c=([itex] \equiv [/itex]3 mod 4)
2a+b+5c=([itex] \equiv [/itex]3 mod 4)
3c-b=([itex] \equiv [/itex]3 mod 4)

Which reduces to the original problem, how to find the number of solutions to a system where each equation equals a distinct prime.

At the moment, I don't see how number theory adds any knowledge to the solution of the problem that isn't already present in the ordinary theory of solving simultaneous linear equations.

If the determinant of the coefficients is not zero, the equations have a unique solution and either it meets your requirements or it doesn't.

A more interesting case is when there are infinitely many solutions. Then they are a subset of [itex]R^3 [/itex]. What does this space look like? I suppose the usual way to write it is to let [itex] (a_0,b_0,c_0) [/itex] be one particular solution to the equations. Then each solution can be written as [itex] (a_0,b_0,c_0) + v [/itex] where [itex] v [/itex] is a solution to the homogenous equations

3a+2b+c=0
2a+b+5c=0
3c-b=0

The set of solutions looks like a vector subspace of [itex] R^3 [/itex] that has been translated away from the origin by adding the vector [itex] (a_0,b_0,c_0) [/itex] to each of its points. To get an answer that meets your requirements, you must determine if that set contains some member of a lattice of points.

Determining the answer to that might involve some number theory, but I'm still not sure if that's the kind of thing you have in mind.

If you solved for p in a vector subspace of the prime numbers instead of the real numbers, would that accomplish anything?
3a+2b+c-p[itex]_{1}[/itex]=0
2a+b+5c-p[itex]_{2}[/itex]=0
3c-b-p[itex]_{3}[/itex]=0
You could use your idea to solve for a,b, and c over the reals and then solve for p over the primes. The only thing is I was looking for a way of determining the number of solutions without solving explicitly.

If you were thinking about applying group theory to the problem, I assume you were thinking about permutation groups What things were you going to permute with the permutations?

Yes, I was thinking about permutation groups, which is why I though Galois Theory might be useful. My idea was that you could think of the problem as permuting the digits in a base m arithmetic to form a three digit prime. Where m= max(α[itex]_{i}[/itex],β[itex]_{i}[/itex],ζ[itex]_{i}[/itex]).
 
  • #10
joebohr said:
Yes, but you could easily introduce number theory by writing the specific cases and finding the number of solutions to the equations
3a+2b+c=([itex] \equiv [/itex]1 mod 4)
2a+b+5c=([itex] \equiv [/itex]1 mod 4)
3c-b=([itex] \equiv [/itex]1 mod 4)
3a+2b+c=([itex] \equiv [/itex]3 mod 4)
2a+b+5c=([itex] \equiv [/itex]3 mod 4)
3c-b=([itex] \equiv [/itex]3 mod 4)

Which reduces to the original problem, how to find the number of solutions to a system where each equation equals a distinct prime.

I don't see the connection between those equations and the original problem. If those are 6 simultaneous equations then they have no solution.
If you solved for p in a vector subspace of the prime numbers instead of the real numbers, would that accomplish anything?

How do you intend to define a "vector subspace of the prime numbers"?

You could use your idea to solve for a,b, and c over the reals and then solve for p over the primes.
Solve for p? In your exampe, are p1 and p2 are given primes or are they unknowns to be solved for along with a,b,c ?


My idea was that you could think of the problem as permuting the digits in a base m arithmetic to form a three digit prime. Where m= max(α[itex]_{i}[/itex],β[itex]_{i}[/itex],ζ[itex]_{i}[/itex]).

I have no idea what you mean by that.
 
  • #11
Stephen Tashi said:
I don't see the connection between those equations and the original problem. If those are 6 simultaneous equations then they have no solution.

Sorry, a bit of a formatting issue. I meant to say:
3a+2b+c[itex] \equiv [/itex]1 mod 4
2a+b+5c[itex] \equiv [/itex]1 mod 4
3c-b[itex] \equiv [/itex]1 mod 4
3a+2b+c[itex] \equiv [/itex]3 mod 4
2a+b+5c[itex] \equiv [/itex]3 mod 4
3c-b[itex] \equiv [/itex]3 mod 4

Since every prime is either congruent to 1 mod 4 or 3 mod 4 (except 2). This isn't very useful solving over the reals, but since we know the solutions need to be less than n (say 12), this might help with formulating a general class of solutions.

Stephen Tashi said:
How do you intend to define a "vector subspace of the prime numbers"?

Perhaps it wasn't phrased correctly but I was asking if you could use your technique of setting the RHS equal to zero and solve for solutions of p that are elements in the set of primes. Probably not going to get anywhere with this, unless there is some technique that I cannot think of for solving within a particular set. I would assume the process wouldn't be too different from ascertaining the number of solutions in another set (such as the rationals), but I may be mistaken.

Stephen Tashi said:
Solve for p? In your example, are p1 and p2 are given primes or are they unknowns to be solved for along with a,b,c ?
p[itex]_{i}[/itex] (i abbreviated the subscript for simplification purposes) are unknown primes. However, I am not concerned with the solutions for a,b,c,p[itex]_{1}[/itex],p[itex]_{2}[/itex],p[itex]_{3}[/itex] etc. but rather with the process of using Galois Theory/Number Theory to solve a general system in the form α[itex]_{i}[/itex]x[itex]_{i}[/itex]+β[itex]_{i}[/itex]y[itex]_{i}[/itex]+ζ[itex]_{i}[/itex]z[itex]_{i}[/itex]=p[itex]_{i}[/itex] where, once again, each α,β,ζ are constants, each p is a distinct prime, and x,y,z are all variables?




Stephen Tashi said:
I have no idea what you mean by that.

I meant that each equation could be written as 3 digit primes where a,b,c are variables which could be permuted as digits rather than roots. For example, set λ equal to the coefficient of the variable y (set λ=β[itex]_{1}[/itex]) in the first system. Then the equation

xλ[itex]^{2}[/itex]+yλ+z=p[itex]_{1}[/itex]

Where λ is a constant and x,y,z are variables

Could be written in base g=λ[itex]^{2}[/itex]+1=1+max(α[itex]_{1}[/itex],β[itex]_{1}[/itex],ζ[itex]_{1}[/itex]) as

xyz

With each letter now representing a digit rather than a number.

An example is, say we are trying to solve the equation

4x+2y+z=p[itex]_{1}[/itex]

Then this can be expressed as xyz in base 5 where the digits xyz can be permuted, so long as they form a three digit prime in base 5. The same can work for any base g as long as
λ[itex]^{2}[/itex]=max(α[itex]_{1}[/itex],β[itex]_{1}[/itex],ζ[itex]_{1}[/itex]) implies that λ[itex]^{2}[/itex]=α[itex]_{1}[/itex], λ=β[itex]_{1}[/itex], 1=ζ[itex]_{1}[/itex].

I don't mean to confuse the problem here and I know I am not being consistent with my examples but I am just trying to come up with some ideas that could help find a solution.
 
  • #12
joebohr said:
Sorry, a bit of a formatting issue. I meant to say:
3a+2b+c[itex] \equiv [/itex]1 mod 4
2a+b+5c[itex] \equiv [/itex]1 mod 4
3c-b[itex] \equiv [/itex]1 mod 4
3a+2b+c[itex] \equiv [/itex]3 mod 4
2a+b+5c[itex] \equiv [/itex]3 mod 4
3c-b[itex] \equiv [/itex]3 mod 4

But pairs of equations like
3c-b[itex] \equiv [/itex]1 mod 4
3c-b[itex] \equiv [/itex]3 mod 4
are inconsistent with each other.

if you could use your technique of setting the RHS equal to zero and solve for solutions of p that are elements in the set of primes.
We're need to get straight which variables are unknowns and which are given in this problem. If we set the right hand side of the equations equal to zero, what would you mean by "solutions of p" ? Aren't the primes p what makes up the right hand side of the equations?



However, I am not concerned with the solutions for a,b,c,p[itex]_{1}[/itex],p[itex]_{2}[/itex],p[itex]_{3}[/itex] etc. but rather with the process of using Galois Theory/Number Theory to solve a general system in the form α[itex]_{i}[/itex]x[itex]_{i}[/itex]+β[itex]_{i}[/itex]y[itex]_{i}[/itex]+ζ[itex]_{i}[/itex]z[itex]_{i}[/itex]=p[itex]_{i}[/itex] where, once again, each α,β,ζ are constants, each p is a distinct prime, and x,y,z are all variables?
Is the condition that "each p is a distinct prime" a new requirement? You need to make a precise statement of the problem that you want to solve, including a statement of exactly which things in the problem are variables and which are known constants.

An example is, say we are trying to solve the equation

4x+2y+z=p[itex]_{1}[/itex]

Then this can be expressed as xyz in base 5 where the digits xyz can be permuted, so long as they form a three digit prime in base 5. The same can work for any base g as long as
λ[itex]^{2}[/itex]=max(α[itex]_{1}[/itex],β[itex]_{1}[/itex],ζ[itex]_{1}[/itex]) implies that λ[itex]^{2}[/itex]=α[itex]_{1}[/itex], λ=β[itex]_{1}[/itex], 1=ζ[itex]_{1}[/itex].

I still don't understand. To me, the sequence of digits xyz in base 5 represents the number 25x + 5y + z and I don't see what that has to do with the original equation
 
  • #13
Stephen Tashi said:
But pairs of equations like
3c-b[itex] \equiv [/itex]1 mod 4
3c-b[itex] \equiv [/itex]3 mod 4
are inconsistent with each other.

Yes, I thought the OR was implied, but I probably should have specified that since I wanted to know the number of solutions that I would account for
3c-b[itex] \equiv [/itex]1 mod 4 Or 3c-b[itex] \equiv [/itex]3 mod 4 being true.

Stephen Tashi said:
We're need to get straight which variables are unknowns and which are given in this problem. If we set the right hand side of the equations equal to zero, what would you mean by "solutions of p" ? Aren't the primes p what makes up the right hand side of the equations?

The coefficients α,β,ζ are given but the variables a,b,c (or x,y,z as I used earlier) as well as the primes p are unknown. I thought that by subtracting p from each side and merging it with the term with a coefficient of 1, since this would not change the number of solutions in Galois Theory since it would then be in the form (using the base 2 example mentioned below)
4a+2b+d=0
Where d is a constant formed by the sum of c and p, which does not change the number of solutions.


Stephen Tashi said:
Is the condition that "each p is a distinct prime" a new requirement? You need to make a precise statement of the problem that you want to solve, including a statement of exactly which things in the problem are variables and which are known constants.

Pretty sure that "each p is a distinct prime" is not a new requirement since I copy pasted from an earlier post:
joebohr said:
Which reduces to the original problem, how to find the number of solutions to a system where each equation equals a distinct prime.

I thought I made it pretty clear which were variables and which were constants, but I understand that there was some confusion about whether p was known or not and I hope I have cleared that up.

Stephen Tashi said:
I still don't understand. To me, the sequence of digits xyz in base 5 represents the number 25x + 5y + z and I don't see what that has to do with the original equation

Sorry, I meant to say base 2, my bad.

Also, I just decided to look into something you said earlier:
Stephen Tashi said:
So we assume n is a prime number.
I think there is a well developed theory of solving a single linear congruence in several unknowns. I don't know that theory by memory. I'd have to look it up.

This might be on to something, using the number theory technique of writing equations that are equivalent to a prime as congruences, one could use this: https://en.wikipedia.org/wiki/Linear_congruence_theorem to determine the possible solutions.

Wikipedia also says that: "In particular, there will be exactly d = gcd(a,n) solutions in the set of residues {0,1,2,...,n-1}," referring to the equation ax[itex]\equiv[/itex]b mod n.

The bottom of the page explains how to solve a system of linear congruences, but this technique would only get me the number of solutions to the system of congruences in the form αx+βb+ζc[itex]\equiv[/itex]3 mod 4 or αx+βb+ζc[itex]\equiv[/itex]1 mod 4, without regard for the fact that these congruences don't necessarily define the original problem precisely (because not all numbers k such that k [itex]\equiv[/itex]3 mod 4 or k[itex]\equiv[/itex]1 mod 4 are necessarily prime numbers). This definitely helps narrow down the solutions and make some progress, but I don't know what to do from there.
 
Last edited:
  • #14
A significant aspect of the permutations in the groups that arise in Galois theory is that the leave some important quantities unchanged. I don't see how your example of permuting digits of a number leaves any important quantity in the problem unchanged.

It's probably best to analyze the specific example. That may clarify the generalities.

Check my work, it probably needs some correction.


3a+2b+c=p1
2a+b+5c=p2
3c-b=p3

----

3a + 2b + c - p1 = 0
2a + b + 5c - p2 = 0
3c - b - p3 = 0

----

6a + 4b + 2c - 2p1 = 0
6a + 3b + 15c - 3p2 = 0
-b + 3c - p3 = 0

-----

b - 13c -2p1 + 3p2 = 0
-b + 3c - p3 = 0

-----

16c - 2p1 + 3p2 - p3 = 0


------

So if we pick any 3 distinct primes p1,p2,p3
then solutions for a,b,c are given by:

c = (1/16)(2p1 - 3p2 + p3) = ((1/8)p1 - (3/16)p2 + (1/16)p3

b = 3c - p3 = (3/16)(2p1 - 3p2 + p3) - p3 = (6/16)p1 - (9/16)p2 - (13/16)p3

a = (1/2)( -b - 5c - p2) = (1/2)(-3c + p3 - 5c - p2) = (1/2)(-8c - p2 + p3)
= (1/2) ( (-8)(1/16)(2p1 - 3p2 + p3 ) - p2 + p3)
= (1/2)( (-1/2)(2p1 - 3p2 + p3) - p2 + p3
= (1/2) (-p1 + (3/2)p2 - (1/2)p3) - p2 + p3
= (-1/2)p1 + (3/4)p2 (-1/4)p3 - p2 + p3
= (-1/2)p1 -(1/4)p2 + (3/4)p3

If we require each of a,b,c to be one of the integers {1,2,3...12}, we have:

[tex] 0 \le (1/8)p1 - (3/16)p2 + (1/16) p3 \le 12 [/tex]
[tex] 0 \le (6/16)p1 - (9/16)p2 - (13/16)p3 \le 12 [/tex]
[tex] 0 \le (-1/2)p1 - (1/4)p2 + (3/4)p3 \le 12 [/tex]

So the theory of solving simultaneous linear inequalties (I assume there is such a theory) is relevant.

The requirement that a,b,c be integers may introduce some number theory.

For example what kind of p1,p2,p3 will make a = (-1/2)p1 - (1/4)p2 + (3/4)p3 an integer?

4a = -2p1 - p2 + 3p3 So -2p1 - p2 + 3p3 is divisible by 4.

We get simultaneous linear congruences

[tex] -2p1 - p2 + 3p3 \equiv 0 (mod 4) [/tex]
[tex] 6p1 - 9p2 - 12p3 \equiv 0 (mod 16) [/tex]
[tex] 2p1 - 3p2 + p3 \equiv 0 (mod 16) [/tex]

There are a limited number of possibilties for the results of things like ( p1 mod 16) since p1 is prime. It looks like an interesting combinatorial problem to try the various combinations and see which ones are feasible in those equations.
 
  • #15
Stephen Tashi said:
A significant aspect of the permutations in the groups that arise in Galois theory is that the leave some important quantities unchanged. I don't see how your example of permuting digits of a number leaves any important quantity in the problem unchanged.

I thought that since permuting the digits leaves the fact that the number is prime the same makes Galois theory relevant. I may have been wrong in hindsight...

Stephen Tashi said:
It's probably best to analyze the specific example. That may clarify the generalities.

Check my work, it probably needs some correction.


3a+2b+c=p1
2a+b+5c=p2
3c-b=p3

----

3a + 2b + c - p1 = 0
2a + b + 5c - p2 = 0
3c - b - p3 = 0

----

6a + 4b + 2c - 2p1 = 0
6a + 3b + 15c - 3p2 = 0
-b + 3c - p3 = 0

-----

b - 13c -2p1 + 3p2 = 0
-b + 3c - p3 = 0

-----

16c - 2p1 + 3p2 - p3 = 0


------

So if we pick any 3 distinct primes p1,p2,p3
then solutions for a,b,c are given by:

c = (1/16)(2p1 - 3p2 + p3) = ((1/8)p1 - (3/16)p2 + (1/16)p3

b = 3c - p3 = (3/16)(2p1 - 3p2 + p3) - p3 = (6/16)p1 - (9/16)p2 - (13/16)p3

a = (1/2)( -b - 5c - p2) = (1/2)(-3c + p3 - 5c - p2) = (1/2)(-8c - p2 + p3)
= (1/2) ( (-8)(1/16)(2p1 - 3p2 + p3 ) - p2 + p3)
= (1/2)( (-1/2)(2p1 - 3p2 + p3) - p2 + p3
= (1/2) (-p1 + (3/2)p2 - (1/2)p3) - p2 + p3
= (-1/2)p1 + (3/4)p2 (-1/4)p3 - p2 + p3
= (-1/2)p1 -(1/4)p2 + (3/4)p3

Not sure, but I think you made an error somewhere. Maybe at the first substitution? I got
a = 1/10 (8p1-7p2+9p3)
b = 1/10 (9p2-6p1-13p3)
and c = 1/10 (3p2-2p1-p3)

Stephen Tashi said:
If we require each of a,b,c to be one of the integers {1,2,3...12}, we have:

[tex] 0 \le (1/8)p1 - (3/16)p2 + (1/16) p3 \le 12 [/tex]
[tex] 0 \le (6/16)p1 - (9/16)p2 - (13/16)p3 \le 12 [/tex]
[tex] 0 \le (-1/2)p1 - (1/4)p2 + (3/4)p3 \le 12 [/tex]

So the theory of solving simultaneous linear inequalties (I assume there is such a theory) is relevant.

It's the same as with linear equalities, we subtract, substitute, and find that the solutions satisfy

(1/9)*(7p2-8p1)<=p3<=(1/9)*(-8p1+7p2+120)

Stephen Tashi said:
The requirement that a,b,c be integers may introduce some number theory.

For example what kind of p1,p2,p3 will make a = (-1/2)p1 - (1/4)p2 + (3/4)p3 an integer?

4a = -2p1 - p2 + 3p3 So -2p1 - p2 + 3p3 is divisible by 4.

We get simultaneous linear congruences

[tex] -2p1 - p2 + 3p3 \equiv 0 (mod 4) [/tex]
[tex] 6p1 - 9p2 - 12p3 \equiv 0 (mod 16) [/tex]
[tex] 2p1 - 3p2 + p3 \equiv 0 (mod 16) [/tex]

There are a limited number of possibilties for the results of things like ( p1 mod 16) since p1 is prime. It looks like an interesting combinatorial problem to try the various combinations and see which ones are feasible in those equations.

Would I be correct in assuming that [tex] -2p1 - p2 + 3p3 \equiv 0 (mod 4) [/tex] has r solutions in the residue class mod 12 where r=gcd{-2p1 - p2 + 3p3,12}=gcd{-2,-1,3,12}=1? That would mean that the entire system has no more than 1 solution in the residue class mod 12. Is this reasoning effective, or even correct?
 
  • #16
joebohr said:
Would I be correct in assuming that [tex] -2p1 - p2 + 3p3 \equiv 0 (mod 4) [/tex] has r solutions in the residue class mod 12

I don't know what it means for a congruence mod 4 to have "solutions in the residue class mod 12". Can you give a numerical example of that?
 
  • #17
Stephen Tashi said:
I don't know what it means for a congruence mod 4 to have "solutions in the residue class mod 12". Can you give a numerical example of that?

What I meant (and I was probably using incorrect terminology) was that the congruence has 1 solution that is less than 12.
 
  • #19
I don't know why I put a 12 either; you're right, it's obviously supposed to be a 4. The GCD would still be 1, though.

More info about Florentin Smarandache and Linear Bialgebra

http://translate.google.com/translate?hl=en&sl=ro&u=http://ro.wikipedia.org/wiki/Florentin_Smarandache&ei=XpQUT6jNC-nf0QG_9fj_Ag&sa=X&oi=translate&ct=result&resnum=4&ved=0CEoQ7gEwAw&prev=/search%3Fq%3DFlorentin%2BSmarandache%26hl%3Den%26client%3Dsafari%26sa%3DX%26rls%3Den%26biw%3D1024%26bih%3D887%26prmd%3Dimvnso

http://en.wikipedia.org/wiki/Bialgebra

"arxiv.org/pdf/math/0508260"
 
Last edited by a moderator:
  • #20
According to Theorem 3 of the Samarandache paper, −2p1−p2+3p3≡0(mod4) has [itex] (1)(4^{2}) [/itex] solutions. To this, we are adding the condition that the p's be distinct primes. So there might be zero solutions. We'll have to work it out to see.
 
  • #21
Stephen Tashi said:
According to Theorem 3 of the Samarandache paper, −2p1−p2+3p3≡0(mod4) has [itex] (1)(4^{2}) [/itex] solutions. To this, we are adding the condition that the p's be distinct primes. So there might be zero solutions. We'll have to work it out to see.

Ok, if we started at
a = 1/10 (8p1-7p2+9p3)
b = 1/10 (9p2-6p1-13p3)
and c = 1/10 (3p2-2p1-p3)

Then what would these congruences look like and how many solutions would they have?

Ultimately, we're going to get a large number (the sum of six numbers each that represent the number of solutions to the 6 congruences), but we need to narrow down the number of solutions to account for the fact that not every x that is congruent to 1 mod 4 or 3 mod 4 is a prime. Then we have to test for 2, which should be easy (equate each of the 3 primes to 2 and see if the simultaneous equations have a solution.
 

1. What is a Galois group for a system of linear equations?

A Galois group for a system of linear equations is a mathematical group that represents the symmetries of the roots of the system of equations. It helps to understand the structure and solutions of the system of equations.

2. How is a Galois group calculated for a system of linear equations?

The Galois group for a system of linear equations is calculated by finding the roots of the equations and then determining the automorphisms, or symmetries, of these roots. These automorphisms form the Galois group, and can be represented using permutation matrices.

3. What information can a Galois group provide about a system of linear equations?

A Galois group can provide information about the solvability of the system of linear equations, as well as the number of distinct solutions. It can also help to determine the degree of the field extension that is needed to find these solutions.

4. Can a Galois group be used to solve a system of linear equations?

No, a Galois group is not directly used to solve a system of linear equations. It is primarily used to understand the structure and properties of the solutions of the equations.

5. Are there any real-world applications of Galois groups for systems of linear equations?

Yes, Galois groups have applications in cryptography, specifically in public key encryption algorithms such as RSA. They are also used in algebraic geometry and number theory to study the structure of polynomial equations.

Similar threads

  • Linear and Abstract Algebra
Replies
3
Views
923
  • Linear and Abstract Algebra
Replies
17
Views
4K
  • Linear and Abstract Algebra
Replies
5
Views
1K
  • Linear and Abstract Algebra
Replies
4
Views
2K
  • Linear and Abstract Algebra
Replies
9
Views
1K
  • Linear and Abstract Algebra
Replies
6
Views
1K
  • Linear and Abstract Algebra
Replies
9
Views
2K
  • Linear and Abstract Algebra
Replies
1
Views
883
  • Linear and Abstract Algebra
Replies
1
Views
2K
Replies
4
Views
620
Back
Top