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Difference between revisions of "Frobenius problem"

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''coin-change problem''
 
''coin-change problem''
  
Given <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/f/f110/f110200/f1102001.png" /> natural numbers <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/f/f110/f110200/f1102002.png" /> with greatest common divisor <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/f/f110/f110200/f1102003.png" />, find the largest natural number that is not expressible as a linear non-negative integer combination of the <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/f/f110/f110200/f1102004.png" />.
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Given $n$ natural numbers $a_1,\ldots,a_n$ with greatest common divisor $1$, find the largest natural number that is not expressible as a linear non-negative integer combination of the $a_1,\ldots,a_n$.
  
For <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/f/f110/f110200/f1102005.png" /> the answer is given by <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/f/f110/f110200/f1102006.png" />. The general problem is <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/f/f110/f110200/f1102008.png" />-hard.
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For $n=2$ the answer is given by $a_1a_2-a_1-a_2$. The general problem is $\mathcal{NP}$-hard.
  
For a fixed <img align="absmiddle" border="0" src="https://www.encyclopediaofmath.org/legacyimages/f/f110/f110200/f1102009.png" /> there is a polynomial-time algorithm to solve the Frobenius problem, [[#References|[a1]]].
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For a fixed $n$ there is a polynomial-time algorithm to solve the Frobenius problem, [[#References|[a1]]].
  
The Frobenius problem is related to the study of maximal lattice-point-free convex bodies (in the [[Geometry of numbers|geometry of numbers]]), [[#References|[a2]]].
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The Frobenius problem is related to the study of maximal lattice-point-free convex bodies (in the [[geometry of numbers]]), [[#References|[a2]]].
  
 
====References====
 
====References====
<table><TR><TD valign="top">[a1]</TD> <TD valign="top">  R. Kannan,  "Lattice translates of a polytope and the Frobenius problem"  ''Combinatorica'' , '''12'''  (1992)  pp. 161–172</TD></TR><TR><TD valign="top">[a2]</TD> <TD valign="top">  L. Lovász,  "Geometry of numbers and integer programming"  M. Iri (ed.)  K. Tanabe (ed.) , ''Mathematical Programming'' , Kluwer Acad. Publ.  (1989)  pp. 177–202</TD></TR></table>
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<table>
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<TR><TD valign="top">[a1]</TD> <TD valign="top">  R. Kannan,  "Lattice translates of a polytope and the Frobenius problem"  ''Combinatorica'' , '''12'''  (1992)  pp. 161–172</TD></TR>
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<TR><TD valign="top">[a2]</TD> <TD valign="top">  L. Lovász,  "Geometry of numbers and integer programming"  M. Iri (ed.)  K. Tanabe (ed.) , ''Mathematical Programming'' , Kluwer Acad. Publ.  (1989)  pp. 177–202</TD></TR>
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</table>

Latest revision as of 21:17, 8 April 2018

2020 Mathematics Subject Classification: Primary: 11D07 [MSN][ZBL]

coin-change problem

Given $n$ natural numbers $a_1,\ldots,a_n$ with greatest common divisor $1$, find the largest natural number that is not expressible as a linear non-negative integer combination of the $a_1,\ldots,a_n$.

For $n=2$ the answer is given by $a_1a_2-a_1-a_2$. The general problem is $\mathcal{NP}$-hard.

For a fixed $n$ there is a polynomial-time algorithm to solve the Frobenius problem, [a1].

The Frobenius problem is related to the study of maximal lattice-point-free convex bodies (in the geometry of numbers), [a2].

References

[a1] R. Kannan, "Lattice translates of a polytope and the Frobenius problem" Combinatorica , 12 (1992) pp. 161–172
[a2] L. Lovász, "Geometry of numbers and integer programming" M. Iri (ed.) K. Tanabe (ed.) , Mathematical Programming , Kluwer Acad. Publ. (1989) pp. 177–202
How to Cite This Entry:
Frobenius problem. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Frobenius_problem&oldid=16167
This article was adapted from an original article by M. Hazewinkel (originator), which appeared in Encyclopedia of Mathematics - ISBN 1402006098. See original article