A proof on interval order











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Let $X$ be a nonempty finite set and $≻$ a binary relation on X. We say that $≻$ is an interval order if $x≻y$ and $x'≻y'$ imply either $x≻y'$ or $x'≻y$, for every $x$,$y$,$x'$ and $y'$ in $X$.



Prove that $≻$ is an interval order iff there exist two real functions $f$ and $g$ on $X$ such that $x≻y$ iff $f(x)>g(y)$ for every $x$ and $y$ in $X$.










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    Let $X$ be a nonempty finite set and $≻$ a binary relation on X. We say that $≻$ is an interval order if $x≻y$ and $x'≻y'$ imply either $x≻y'$ or $x'≻y$, for every $x$,$y$,$x'$ and $y'$ in $X$.



    Prove that $≻$ is an interval order iff there exist two real functions $f$ and $g$ on $X$ such that $x≻y$ iff $f(x)>g(y)$ for every $x$ and $y$ in $X$.










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      up vote
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      down vote

      favorite









      up vote
      -1
      down vote

      favorite











      Let $X$ be a nonempty finite set and $≻$ a binary relation on X. We say that $≻$ is an interval order if $x≻y$ and $x'≻y'$ imply either $x≻y'$ or $x'≻y$, for every $x$,$y$,$x'$ and $y'$ in $X$.



      Prove that $≻$ is an interval order iff there exist two real functions $f$ and $g$ on $X$ such that $x≻y$ iff $f(x)>g(y)$ for every $x$ and $y$ in $X$.










      share|cite|improve this question







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      qwert3 is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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      Let $X$ be a nonempty finite set and $≻$ a binary relation on X. We say that $≻$ is an interval order if $x≻y$ and $x'≻y'$ imply either $x≻y'$ or $x'≻y$, for every $x$,$y$,$x'$ and $y'$ in $X$.



      Prove that $≻$ is an interval order iff there exist two real functions $f$ and $g$ on $X$ such that $x≻y$ iff $f(x)>g(y)$ for every $x$ and $y$ in $X$.







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