Formulas for full m-ary trees












0












$begingroup$


I am studying for an upcoming Discrete Math exam, and the final section is on trees. I understand the theory, but some of the questions require memorizing several formulas for calculating the number of vertices, internal vertices, and leaves.



The professor mentioned that there are maybe just 2 formulas we should learn and algebraically derive the rest, but I am unsure which 2 I should memorize. Any help would be appreciated!




n vertices has i = (n – 1)/m internal vertices and l = [(m – 1)n +
1]/m leaves i internal vertices has n = mi + 1 vertices and l = (m –
1)i + 1 leaves l leaves has n = (ml – 1)/(m – 1) vertices and i = (l –
1)/(m – 1) internal vertices




Edit:
n = vertices
m = edges










share|cite|improve this question











$endgroup$












  • $begingroup$
    Uhm... so regarding your course which include trees, you want us to give you the most important formulas... ? You will either have to provide a lot more detailed information on the content of the course or actually ask the teacher... We can guess "tree Theorems" for page up and page down, without coming close to what you want to know and even less find "the most important 2 of the course".
    $endgroup$
    – Ove Ahlman
    Dec 6 '17 at 12:35












  • $begingroup$
    Fair point, I have updated with all 6 formulas given.
    $endgroup$
    – jdc220
    Dec 6 '17 at 12:45










  • $begingroup$
    Your quote is missing context. What is $m$? Are you talking about an $m$-ary tree?
    $endgroup$
    – darij grinberg
    Feb 3 at 5:40










  • $begingroup$
    Good call. m = number of edges.
    $endgroup$
    – jdc220
    Feb 3 at 14:59
















0












$begingroup$


I am studying for an upcoming Discrete Math exam, and the final section is on trees. I understand the theory, but some of the questions require memorizing several formulas for calculating the number of vertices, internal vertices, and leaves.



The professor mentioned that there are maybe just 2 formulas we should learn and algebraically derive the rest, but I am unsure which 2 I should memorize. Any help would be appreciated!




n vertices has i = (n – 1)/m internal vertices and l = [(m – 1)n +
1]/m leaves i internal vertices has n = mi + 1 vertices and l = (m –
1)i + 1 leaves l leaves has n = (ml – 1)/(m – 1) vertices and i = (l –
1)/(m – 1) internal vertices




Edit:
n = vertices
m = edges










share|cite|improve this question











$endgroup$












  • $begingroup$
    Uhm... so regarding your course which include trees, you want us to give you the most important formulas... ? You will either have to provide a lot more detailed information on the content of the course or actually ask the teacher... We can guess "tree Theorems" for page up and page down, without coming close to what you want to know and even less find "the most important 2 of the course".
    $endgroup$
    – Ove Ahlman
    Dec 6 '17 at 12:35












  • $begingroup$
    Fair point, I have updated with all 6 formulas given.
    $endgroup$
    – jdc220
    Dec 6 '17 at 12:45










  • $begingroup$
    Your quote is missing context. What is $m$? Are you talking about an $m$-ary tree?
    $endgroup$
    – darij grinberg
    Feb 3 at 5:40










  • $begingroup$
    Good call. m = number of edges.
    $endgroup$
    – jdc220
    Feb 3 at 14:59














0












0








0





$begingroup$


I am studying for an upcoming Discrete Math exam, and the final section is on trees. I understand the theory, but some of the questions require memorizing several formulas for calculating the number of vertices, internal vertices, and leaves.



The professor mentioned that there are maybe just 2 formulas we should learn and algebraically derive the rest, but I am unsure which 2 I should memorize. Any help would be appreciated!




n vertices has i = (n – 1)/m internal vertices and l = [(m – 1)n +
1]/m leaves i internal vertices has n = mi + 1 vertices and l = (m –
1)i + 1 leaves l leaves has n = (ml – 1)/(m – 1) vertices and i = (l –
1)/(m – 1) internal vertices




Edit:
n = vertices
m = edges










share|cite|improve this question











$endgroup$




I am studying for an upcoming Discrete Math exam, and the final section is on trees. I understand the theory, but some of the questions require memorizing several formulas for calculating the number of vertices, internal vertices, and leaves.



The professor mentioned that there are maybe just 2 formulas we should learn and algebraically derive the rest, but I am unsure which 2 I should memorize. Any help would be appreciated!




n vertices has i = (n – 1)/m internal vertices and l = [(m – 1)n +
1]/m leaves i internal vertices has n = mi + 1 vertices and l = (m –
1)i + 1 leaves l leaves has n = (ml – 1)/(m – 1) vertices and i = (l –
1)/(m – 1) internal vertices




Edit:
n = vertices
m = edges







discrete-mathematics graph-theory trees






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Feb 3 at 14:57







jdc220

















asked Dec 6 '17 at 12:32









jdc220jdc220

287




287












  • $begingroup$
    Uhm... so regarding your course which include trees, you want us to give you the most important formulas... ? You will either have to provide a lot more detailed information on the content of the course or actually ask the teacher... We can guess "tree Theorems" for page up and page down, without coming close to what you want to know and even less find "the most important 2 of the course".
    $endgroup$
    – Ove Ahlman
    Dec 6 '17 at 12:35












  • $begingroup$
    Fair point, I have updated with all 6 formulas given.
    $endgroup$
    – jdc220
    Dec 6 '17 at 12:45










  • $begingroup$
    Your quote is missing context. What is $m$? Are you talking about an $m$-ary tree?
    $endgroup$
    – darij grinberg
    Feb 3 at 5:40










  • $begingroup$
    Good call. m = number of edges.
    $endgroup$
    – jdc220
    Feb 3 at 14:59


















  • $begingroup$
    Uhm... so regarding your course which include trees, you want us to give you the most important formulas... ? You will either have to provide a lot more detailed information on the content of the course or actually ask the teacher... We can guess "tree Theorems" for page up and page down, without coming close to what you want to know and even less find "the most important 2 of the course".
    $endgroup$
    – Ove Ahlman
    Dec 6 '17 at 12:35












  • $begingroup$
    Fair point, I have updated with all 6 formulas given.
    $endgroup$
    – jdc220
    Dec 6 '17 at 12:45










  • $begingroup$
    Your quote is missing context. What is $m$? Are you talking about an $m$-ary tree?
    $endgroup$
    – darij grinberg
    Feb 3 at 5:40










  • $begingroup$
    Good call. m = number of edges.
    $endgroup$
    – jdc220
    Feb 3 at 14:59
















$begingroup$
Uhm... so regarding your course which include trees, you want us to give you the most important formulas... ? You will either have to provide a lot more detailed information on the content of the course or actually ask the teacher... We can guess "tree Theorems" for page up and page down, without coming close to what you want to know and even less find "the most important 2 of the course".
$endgroup$
– Ove Ahlman
Dec 6 '17 at 12:35






$begingroup$
Uhm... so regarding your course which include trees, you want us to give you the most important formulas... ? You will either have to provide a lot more detailed information on the content of the course or actually ask the teacher... We can guess "tree Theorems" for page up and page down, without coming close to what you want to know and even less find "the most important 2 of the course".
$endgroup$
– Ove Ahlman
Dec 6 '17 at 12:35














$begingroup$
Fair point, I have updated with all 6 formulas given.
$endgroup$
– jdc220
Dec 6 '17 at 12:45




$begingroup$
Fair point, I have updated with all 6 formulas given.
$endgroup$
– jdc220
Dec 6 '17 at 12:45












$begingroup$
Your quote is missing context. What is $m$? Are you talking about an $m$-ary tree?
$endgroup$
– darij grinberg
Feb 3 at 5:40




$begingroup$
Your quote is missing context. What is $m$? Are you talking about an $m$-ary tree?
$endgroup$
– darij grinberg
Feb 3 at 5:40












$begingroup$
Good call. m = number of edges.
$endgroup$
– jdc220
Feb 3 at 14:59




$begingroup$
Good call. m = number of edges.
$endgroup$
– jdc220
Feb 3 at 14:59










1 Answer
1






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oldest

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1












$begingroup$

Just memorise $n=mi+1$ and $l=(m-1)i+1$. The other formulae are just re-arrangements of these two.



For example, if you know $l$ and $m$ and you want to find $i$ and $n$ then



$l=(m-1)i+1 Rightarrow i=dfrac{l-1}{m-1}$



and



$n=mi+1 Rightarrow n=dfrac{m(l-1)}{m-1}+1=dfrac{ml-m+m-1}{m-1}=dfrac{ml-1}{m-1}$






share|cite|improve this answer









$endgroup$













  • $begingroup$
    thank you! This is exactly what I was trying to figure out.
    $endgroup$
    – jdc220
    Dec 6 '17 at 13:18












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1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

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active

oldest

votes









1












$begingroup$

Just memorise $n=mi+1$ and $l=(m-1)i+1$. The other formulae are just re-arrangements of these two.



For example, if you know $l$ and $m$ and you want to find $i$ and $n$ then



$l=(m-1)i+1 Rightarrow i=dfrac{l-1}{m-1}$



and



$n=mi+1 Rightarrow n=dfrac{m(l-1)}{m-1}+1=dfrac{ml-m+m-1}{m-1}=dfrac{ml-1}{m-1}$






share|cite|improve this answer









$endgroup$













  • $begingroup$
    thank you! This is exactly what I was trying to figure out.
    $endgroup$
    – jdc220
    Dec 6 '17 at 13:18
















1












$begingroup$

Just memorise $n=mi+1$ and $l=(m-1)i+1$. The other formulae are just re-arrangements of these two.



For example, if you know $l$ and $m$ and you want to find $i$ and $n$ then



$l=(m-1)i+1 Rightarrow i=dfrac{l-1}{m-1}$



and



$n=mi+1 Rightarrow n=dfrac{m(l-1)}{m-1}+1=dfrac{ml-m+m-1}{m-1}=dfrac{ml-1}{m-1}$






share|cite|improve this answer









$endgroup$













  • $begingroup$
    thank you! This is exactly what I was trying to figure out.
    $endgroup$
    – jdc220
    Dec 6 '17 at 13:18














1












1








1





$begingroup$

Just memorise $n=mi+1$ and $l=(m-1)i+1$. The other formulae are just re-arrangements of these two.



For example, if you know $l$ and $m$ and you want to find $i$ and $n$ then



$l=(m-1)i+1 Rightarrow i=dfrac{l-1}{m-1}$



and



$n=mi+1 Rightarrow n=dfrac{m(l-1)}{m-1}+1=dfrac{ml-m+m-1}{m-1}=dfrac{ml-1}{m-1}$






share|cite|improve this answer









$endgroup$



Just memorise $n=mi+1$ and $l=(m-1)i+1$. The other formulae are just re-arrangements of these two.



For example, if you know $l$ and $m$ and you want to find $i$ and $n$ then



$l=(m-1)i+1 Rightarrow i=dfrac{l-1}{m-1}$



and



$n=mi+1 Rightarrow n=dfrac{m(l-1)}{m-1}+1=dfrac{ml-m+m-1}{m-1}=dfrac{ml-1}{m-1}$







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered Dec 6 '17 at 13:06









gandalf61gandalf61

9,293825




9,293825












  • $begingroup$
    thank you! This is exactly what I was trying to figure out.
    $endgroup$
    – jdc220
    Dec 6 '17 at 13:18


















  • $begingroup$
    thank you! This is exactly what I was trying to figure out.
    $endgroup$
    – jdc220
    Dec 6 '17 at 13:18
















$begingroup$
thank you! This is exactly what I was trying to figure out.
$endgroup$
– jdc220
Dec 6 '17 at 13:18




$begingroup$
thank you! This is exactly what I was trying to figure out.
$endgroup$
– jdc220
Dec 6 '17 at 13:18


















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