How to reduce 3-COLOR to 42-COLOR?

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1














The requirement is that two adjacent vertices have different colors, and max. 42 colors.



I show that $ text42-COLOR $ is in NP and then I must reduce it from $ text3-COLOR $. Here it becomes complicated.



Is it similar to $ ktext-COLOR $ for any $k$?










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  • Do you want to reduce 42-COLOR to 3-COLOR, or the other way around?
    – Juho
    Dec 16 at 12:00










  • The other way around. $ 3-COLOR propto 42-COLOR $. Now i noticed my mistake.
    – gil
    Dec 16 at 12:27















1














The requirement is that two adjacent vertices have different colors, and max. 42 colors.



I show that $ text42-COLOR $ is in NP and then I must reduce it from $ text3-COLOR $. Here it becomes complicated.



Is it similar to $ ktext-COLOR $ for any $k$?










share|cite|improve this question























  • Do you want to reduce 42-COLOR to 3-COLOR, or the other way around?
    – Juho
    Dec 16 at 12:00










  • The other way around. $ 3-COLOR propto 42-COLOR $. Now i noticed my mistake.
    – gil
    Dec 16 at 12:27













1












1








1







The requirement is that two adjacent vertices have different colors, and max. 42 colors.



I show that $ text42-COLOR $ is in NP and then I must reduce it from $ text3-COLOR $. Here it becomes complicated.



Is it similar to $ ktext-COLOR $ for any $k$?










share|cite|improve this question















The requirement is that two adjacent vertices have different colors, and max. 42 colors.



I show that $ text42-COLOR $ is in NP and then I must reduce it from $ text3-COLOR $. Here it becomes complicated.



Is it similar to $ ktext-COLOR $ for any $k$?







graphs graph-theory np-complete reductions colorings






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share|cite|improve this question













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edited Dec 16 at 14:51









xskxzr

3,4321730




3,4321730










asked Dec 16 at 11:37









gil

62




62











  • Do you want to reduce 42-COLOR to 3-COLOR, or the other way around?
    – Juho
    Dec 16 at 12:00










  • The other way around. $ 3-COLOR propto 42-COLOR $. Now i noticed my mistake.
    – gil
    Dec 16 at 12:27
















  • Do you want to reduce 42-COLOR to 3-COLOR, or the other way around?
    – Juho
    Dec 16 at 12:00










  • The other way around. $ 3-COLOR propto 42-COLOR $. Now i noticed my mistake.
    – gil
    Dec 16 at 12:27















Do you want to reduce 42-COLOR to 3-COLOR, or the other way around?
– Juho
Dec 16 at 12:00




Do you want to reduce 42-COLOR to 3-COLOR, or the other way around?
– Juho
Dec 16 at 12:00












The other way around. $ 3-COLOR propto 42-COLOR $. Now i noticed my mistake.
– gil
Dec 16 at 12:27




The other way around. $ 3-COLOR propto 42-COLOR $. Now i noticed my mistake.
– gil
Dec 16 at 12:27










1 Answer
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For an instance of 3-COLOR, try to add a complete graph of size $k-3$, and add an edge between each new vertex and each old vertex. Now you can prove the new graph is $k$-colorable iff the old graph is 3-colorable.






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    1 Answer
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    1 Answer
    1






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    5














    For an instance of 3-COLOR, try to add a complete graph of size $k-3$, and add an edge between each new vertex and each old vertex. Now you can prove the new graph is $k$-colorable iff the old graph is 3-colorable.






    share|cite|improve this answer

























      5














      For an instance of 3-COLOR, try to add a complete graph of size $k-3$, and add an edge between each new vertex and each old vertex. Now you can prove the new graph is $k$-colorable iff the old graph is 3-colorable.






      share|cite|improve this answer























        5












        5








        5






        For an instance of 3-COLOR, try to add a complete graph of size $k-3$, and add an edge between each new vertex and each old vertex. Now you can prove the new graph is $k$-colorable iff the old graph is 3-colorable.






        share|cite|improve this answer












        For an instance of 3-COLOR, try to add a complete graph of size $k-3$, and add an edge between each new vertex and each old vertex. Now you can prove the new graph is $k$-colorable iff the old graph is 3-colorable.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Dec 16 at 14:55









        xskxzr

        3,4321730




        3,4321730



























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