Solution to Frobenius Problem for N=2: Proof?

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Discussion Overview

The discussion revolves around the Frobenius problem for two integers, specifically seeking a proof for the assertion that the smallest non-expressible number as a linear combination of two integers \(a\) and \(b\) is \((a-1)(b-1)\). Participants explore related concepts and clarify terms used in the problem.

Discussion Character

  • Debate/contested

Main Points Raised

  • One participant questions the validity of the original statement regarding the expressibility of numbers as linear combinations of \(a\) and \(b\), citing an example where 1 is not expressible as a combination of 2 and 4.
  • Another participant references a source that may contain relevant information about the Frobenius problem, suggesting it could provide the proof sought.
  • A different participant asserts that the smallest positive integer expressible as a linear combination of \(a\) and \(b\) is their greatest common divisor (gcd), indicating a potential misunderstanding in the original claim.
  • Clarification is made regarding the terminology used, specifically the distinction between "not expressible" and "positive linear combination."

Areas of Agreement / Disagreement

Participants do not appear to reach a consensus, as there are competing views regarding the original claim and the definitions involved in the discussion.

Contextual Notes

There are unresolved issues regarding the definitions of expressibility and the conditions under which numbers can be expressed as linear combinations of \(a\) and \(b\). The discussion also highlights the importance of distinguishing between positive and non-positive combinations.

adamg
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does anyone know a proof for the solution to the frobenius problem for n=2? that is, that the smallest not possible number expressable as a linear combination of a and b is (a-1)(b-1)??
 
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Are you sure about that (slightly ungrammatical) statement? 1 is not expressible as a linear combination of 2 and 4?
 
This might be what you're looking for: http://www.math.swt.edu/~haz/prob_sets/notes/node11.html (Theorem 1.15)
 
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the smallest positive integer expressible as a linear combination of a and b is their gcd. this is in euclid. oh you had the essential word backwards. and also you seem to have meant positive inear combination.
 
Last edited:

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