Linear Map = Function of degree P-1

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Homework Help Overview

The discussion revolves around proving a property of functions defined on a finite field, specifically that for a prime p, any function from Fp to Fp can be represented by a polynomial of degree at most p-1. The participants explore the implications of polynomial interpolation in this context.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants question whether polynomial interpolation is applicable, considering the finite nature of the field. There is discussion about the relationship between the number of values in Fp and the degree of polynomials.

Discussion Status

The discussion is active, with participants exploring different interpretations of polynomial interpolation and its relevance to the problem. Some express uncertainty about the connection between the function and polynomial representation.

Contextual Notes

There is a noted confusion regarding the linearity of the function f and the implications of working within a finite field. Participants are also considering the constraints of polynomial degrees in relation to the number of values in Fp.

brru25
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If p is prime, prove that for every function f: Fp -> Fp there exists a polynomial Q (depending on f) of degree at most p-1 such that f(x) = Q(x) for each x in Fp.
 
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Would polynomial interpolation work here?
 
I don't see how you could interpolate. There are only p possible values in F_p. I notice you titled this "Linear Map= Function of degree P-1". Do you understand that there is nothing said here about f being linear?
 
Yea I assumed by accident it was linear. Yea I understand that there are only p values in Fp but I don't know how to make the connection to a polynomial. I mean I know a polynomial of degree p-1 has p coefficients but for some reason I can't connect the dots.
 
brru25 said:
Would polynomial interpolation work here?
Have you tried it? What happened?


HallsofIvy said:
I don't see how you could interpolate.
Polynomial interpolation works over any field... or is there something else you see that I don't?
 
Hurkyl said:
Polynomial interpolation works over any field... or is there something else you see that I don't?
Well, I think of "interpolation" as finding values between given values. And since this is a finite field, there is nothing "between" values.
 

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