How much graph instances that have only three degree vertices.











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For one of my algorithms, i'm looking to know what are the graphs that have only three degree vertex.



For example here is the first graph i know, that have this property:



graph example with only 3 degree vetices



Are they other graph instances that have this criterion?



Thank you.










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  • They are called "cubic graphs" and there is tons of literature about them.
    – Michal Adamaszek
    Nov 16 at 13:34










  • @MichalAdamaszek thank you, i will google that word.
    – zak zak
    Nov 16 at 15:29















up vote
0
down vote

favorite












For one of my algorithms, i'm looking to know what are the graphs that have only three degree vertex.



For example here is the first graph i know, that have this property:



graph example with only 3 degree vetices



Are they other graph instances that have this criterion?



Thank you.










share|cite|improve this question






















  • They are called "cubic graphs" and there is tons of literature about them.
    – Michal Adamaszek
    Nov 16 at 13:34










  • @MichalAdamaszek thank you, i will google that word.
    – zak zak
    Nov 16 at 15:29













up vote
0
down vote

favorite









up vote
0
down vote

favorite











For one of my algorithms, i'm looking to know what are the graphs that have only three degree vertex.



For example here is the first graph i know, that have this property:



graph example with only 3 degree vetices



Are they other graph instances that have this criterion?



Thank you.










share|cite|improve this question













For one of my algorithms, i'm looking to know what are the graphs that have only three degree vertex.



For example here is the first graph i know, that have this property:



graph example with only 3 degree vetices



Are they other graph instances that have this criterion?



Thank you.







graph-theory






share|cite|improve this question













share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Nov 16 at 13:06









zak zak

1033




1033












  • They are called "cubic graphs" and there is tons of literature about them.
    – Michal Adamaszek
    Nov 16 at 13:34










  • @MichalAdamaszek thank you, i will google that word.
    – zak zak
    Nov 16 at 15:29


















  • They are called "cubic graphs" and there is tons of literature about them.
    – Michal Adamaszek
    Nov 16 at 13:34










  • @MichalAdamaszek thank you, i will google that word.
    – zak zak
    Nov 16 at 15:29
















They are called "cubic graphs" and there is tons of literature about them.
– Michal Adamaszek
Nov 16 at 13:34




They are called "cubic graphs" and there is tons of literature about them.
– Michal Adamaszek
Nov 16 at 13:34












@MichalAdamaszek thank you, i will google that word.
– zak zak
Nov 16 at 15:29




@MichalAdamaszek thank you, i will google that word.
– zak zak
Nov 16 at 15:29










1 Answer
1






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If such a graph has $V$ vertices and $E$ edges then



$2E = 3V$



so $V$ must be a multiple of $2$ and $E$ must be a multiple of $3$.



Draw two cyclic graphs, each with $n$ vertices. Each vertex has degree $2$. Now create a one-to-one mapping between the vertices in one cycle and the vertices in the other cycle. Add edges linking each vertex in one cycle to the corresponding vertex in the other cycle. Now you have a graph with $2n$ vertices and $3n$ edges where each vertex has degree $3$.






share|cite|improve this answer





















  • Thank you, so there is an infinity of graph instances with that criterion.
    – zak zak
    Nov 16 at 15:44










  • Yes, that is correct.
    – gandalf61
    Nov 16 at 15:58











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1 Answer
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active

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up vote
0
down vote



accepted










If such a graph has $V$ vertices and $E$ edges then



$2E = 3V$



so $V$ must be a multiple of $2$ and $E$ must be a multiple of $3$.



Draw two cyclic graphs, each with $n$ vertices. Each vertex has degree $2$. Now create a one-to-one mapping between the vertices in one cycle and the vertices in the other cycle. Add edges linking each vertex in one cycle to the corresponding vertex in the other cycle. Now you have a graph with $2n$ vertices and $3n$ edges where each vertex has degree $3$.






share|cite|improve this answer





















  • Thank you, so there is an infinity of graph instances with that criterion.
    – zak zak
    Nov 16 at 15:44










  • Yes, that is correct.
    – gandalf61
    Nov 16 at 15:58















up vote
0
down vote



accepted










If such a graph has $V$ vertices and $E$ edges then



$2E = 3V$



so $V$ must be a multiple of $2$ and $E$ must be a multiple of $3$.



Draw two cyclic graphs, each with $n$ vertices. Each vertex has degree $2$. Now create a one-to-one mapping between the vertices in one cycle and the vertices in the other cycle. Add edges linking each vertex in one cycle to the corresponding vertex in the other cycle. Now you have a graph with $2n$ vertices and $3n$ edges where each vertex has degree $3$.






share|cite|improve this answer





















  • Thank you, so there is an infinity of graph instances with that criterion.
    – zak zak
    Nov 16 at 15:44










  • Yes, that is correct.
    – gandalf61
    Nov 16 at 15:58













up vote
0
down vote



accepted







up vote
0
down vote



accepted






If such a graph has $V$ vertices and $E$ edges then



$2E = 3V$



so $V$ must be a multiple of $2$ and $E$ must be a multiple of $3$.



Draw two cyclic graphs, each with $n$ vertices. Each vertex has degree $2$. Now create a one-to-one mapping between the vertices in one cycle and the vertices in the other cycle. Add edges linking each vertex in one cycle to the corresponding vertex in the other cycle. Now you have a graph with $2n$ vertices and $3n$ edges where each vertex has degree $3$.






share|cite|improve this answer












If such a graph has $V$ vertices and $E$ edges then



$2E = 3V$



so $V$ must be a multiple of $2$ and $E$ must be a multiple of $3$.



Draw two cyclic graphs, each with $n$ vertices. Each vertex has degree $2$. Now create a one-to-one mapping between the vertices in one cycle and the vertices in the other cycle. Add edges linking each vertex in one cycle to the corresponding vertex in the other cycle. Now you have a graph with $2n$ vertices and $3n$ edges where each vertex has degree $3$.







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered Nov 16 at 13:51









gandalf61

7,207623




7,207623












  • Thank you, so there is an infinity of graph instances with that criterion.
    – zak zak
    Nov 16 at 15:44










  • Yes, that is correct.
    – gandalf61
    Nov 16 at 15:58


















  • Thank you, so there is an infinity of graph instances with that criterion.
    – zak zak
    Nov 16 at 15:44










  • Yes, that is correct.
    – gandalf61
    Nov 16 at 15:58
















Thank you, so there is an infinity of graph instances with that criterion.
– zak zak
Nov 16 at 15:44




Thank you, so there is an infinity of graph instances with that criterion.
– zak zak
Nov 16 at 15:44












Yes, that is correct.
– gandalf61
Nov 16 at 15:58




Yes, that is correct.
– gandalf61
Nov 16 at 15:58


















 

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