How many matchings does a cycle on n vertices have?












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$begingroup$


how many matchings does a cycle on n vertices have?



this is graph theory.



If n = 3, matching would be 3? and



If n = 4, matching should be 4 and



If n = 5, matching would be 10?



It seems there is no pattern










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$endgroup$








  • 1




    $begingroup$
    How do you get $4$ matchings for a cycle on $4$ vertices? I get $2$ matchings of size $2$, and $4$ matchings of size $1$, and . . . does the empty matching count? I get $7$ matchings, or $6$ nonempty matchings, or $2$ maximum matchings, or $2$ maximal matchings. How do you get $4$?
    $endgroup$
    – bof
    Dec 7 '18 at 3:39












  • $begingroup$
    My guess is that they want you to count all matchings of any size, including the empty matching. In that case there seems to be a nice pattern. I get $4$ matchings for $n=3$, $7$ matchings for $n=4$, $11$ matchings for $n=5$, ...
    $endgroup$
    – bof
    Dec 7 '18 at 3:53
















0












$begingroup$


how many matchings does a cycle on n vertices have?



this is graph theory.



If n = 3, matching would be 3? and



If n = 4, matching should be 4 and



If n = 5, matching would be 10?



It seems there is no pattern










share|cite|improve this question









$endgroup$








  • 1




    $begingroup$
    How do you get $4$ matchings for a cycle on $4$ vertices? I get $2$ matchings of size $2$, and $4$ matchings of size $1$, and . . . does the empty matching count? I get $7$ matchings, or $6$ nonempty matchings, or $2$ maximum matchings, or $2$ maximal matchings. How do you get $4$?
    $endgroup$
    – bof
    Dec 7 '18 at 3:39












  • $begingroup$
    My guess is that they want you to count all matchings of any size, including the empty matching. In that case there seems to be a nice pattern. I get $4$ matchings for $n=3$, $7$ matchings for $n=4$, $11$ matchings for $n=5$, ...
    $endgroup$
    – bof
    Dec 7 '18 at 3:53














0












0








0





$begingroup$


how many matchings does a cycle on n vertices have?



this is graph theory.



If n = 3, matching would be 3? and



If n = 4, matching should be 4 and



If n = 5, matching would be 10?



It seems there is no pattern










share|cite|improve this question









$endgroup$




how many matchings does a cycle on n vertices have?



this is graph theory.



If n = 3, matching would be 3? and



If n = 4, matching should be 4 and



If n = 5, matching would be 10?



It seems there is no pattern







graph-theory matching-theory






share|cite|improve this question













share|cite|improve this question











share|cite|improve this question




share|cite|improve this question










asked Dec 7 '18 at 2:30









Jace ChoJace Cho

1




1








  • 1




    $begingroup$
    How do you get $4$ matchings for a cycle on $4$ vertices? I get $2$ matchings of size $2$, and $4$ matchings of size $1$, and . . . does the empty matching count? I get $7$ matchings, or $6$ nonempty matchings, or $2$ maximum matchings, or $2$ maximal matchings. How do you get $4$?
    $endgroup$
    – bof
    Dec 7 '18 at 3:39












  • $begingroup$
    My guess is that they want you to count all matchings of any size, including the empty matching. In that case there seems to be a nice pattern. I get $4$ matchings for $n=3$, $7$ matchings for $n=4$, $11$ matchings for $n=5$, ...
    $endgroup$
    – bof
    Dec 7 '18 at 3:53














  • 1




    $begingroup$
    How do you get $4$ matchings for a cycle on $4$ vertices? I get $2$ matchings of size $2$, and $4$ matchings of size $1$, and . . . does the empty matching count? I get $7$ matchings, or $6$ nonempty matchings, or $2$ maximum matchings, or $2$ maximal matchings. How do you get $4$?
    $endgroup$
    – bof
    Dec 7 '18 at 3:39












  • $begingroup$
    My guess is that they want you to count all matchings of any size, including the empty matching. In that case there seems to be a nice pattern. I get $4$ matchings for $n=3$, $7$ matchings for $n=4$, $11$ matchings for $n=5$, ...
    $endgroup$
    – bof
    Dec 7 '18 at 3:53








1




1




$begingroup$
How do you get $4$ matchings for a cycle on $4$ vertices? I get $2$ matchings of size $2$, and $4$ matchings of size $1$, and . . . does the empty matching count? I get $7$ matchings, or $6$ nonempty matchings, or $2$ maximum matchings, or $2$ maximal matchings. How do you get $4$?
$endgroup$
– bof
Dec 7 '18 at 3:39






$begingroup$
How do you get $4$ matchings for a cycle on $4$ vertices? I get $2$ matchings of size $2$, and $4$ matchings of size $1$, and . . . does the empty matching count? I get $7$ matchings, or $6$ nonempty matchings, or $2$ maximum matchings, or $2$ maximal matchings. How do you get $4$?
$endgroup$
– bof
Dec 7 '18 at 3:39














$begingroup$
My guess is that they want you to count all matchings of any size, including the empty matching. In that case there seems to be a nice pattern. I get $4$ matchings for $n=3$, $7$ matchings for $n=4$, $11$ matchings for $n=5$, ...
$endgroup$
– bof
Dec 7 '18 at 3:53




$begingroup$
My guess is that they want you to count all matchings of any size, including the empty matching. In that case there seems to be a nice pattern. I get $4$ matchings for $n=3$, $7$ matchings for $n=4$, $11$ matchings for $n=5$, ...
$endgroup$
– bof
Dec 7 '18 at 3:53










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