Dude the word 'Pittel' doesnt have no meaning, and doesnt exist according to the internet!Originally posted by John C
Pinchy you are a hero.
Consider a digital search tree (DST) built over $m$
independently generated binary strings with ''$0$'' occurring with`
probability $p$ and ''$1$'' with probability
$q=1-p$.
Limiting Distribution of the Profile.
Let us fixed $k$ (that may depend on $m$), and define
$B_m^k$ as the number of nodes in the DST at level $k$.
This is called the profile of DST.
We are interested in obtaining the limiting distribution of
$B_m^k$ for any $k$.
Aldous and Shields [AS] established it for the symmetric case.
In the asymmetric case the limiting distribution is unknown.
It is easy to derive a recurrence for $B_m^k$.
Define $B_m^k(u)=Eu^{B_m^k}$. Then
$$
B_{m+1}^k(u)=\sum_{l=0}^m {m \choose l} p^lq^{m-l} B_l^{k-1}(u)
B_{m-l}^{k-1}(u)~,
$$
with $B_0^0(u)=1$. Let now $B^k(z,u)=\sum_{m=0}^\infty B_m^k(u)
{z^m \over m!}$. Then, the above becomes
$$
{\partial B^k(z,u) \over \partial z} =
B^{k-1}(pz,u) B^{k-1}(qz,u)
$$
with $B^0(z,u)=u(e^z-1)+1$. We conjecture that for
$k=O(\log m)$ the limiting distribution of $B_m^k$ is normal.
The average profile was established in [LS]
Limiting Distribution of the Height.
Let $H_n^k$ denote the probability that the {\it height} in a DST
with $m$ nodes is smaller equal to $k$. Define
$H^k(z)=\sum_{m\geq 0} H_m^k {z^m \over m!}$. Then, one
easily see that for $k\geq 1$
$$
{d H^k(z) \over d z} = H^{k-1}(zp) H^{k-1}(zq)
$$
with $H^0(z)=1+z$. What is the limiting distribution of
the height? From [Pittel] we only know
that $H_m /\log m \to 1/\log (\min\{1/p, 1/q\})$
almost surely.
Ill give you half an hour...
Originally posted by John C
Pinchy you are a hero.
Consider a digital search tree (DST) built over $m$
independently generated binary strings with ''$0$'' occurring with`
probability $p$ and ''$1$'' with probability
$q=1-p$.
Limiting Distribution of the Profile.
Let us fixed $k$ (that may depend on $m$), and define
$B_m^k$ as the number of nodes in the DST at level $k$.
This is called the profile of DST.
We are interested in obtaining the limiting distribution of
$B_m^k$ for any $k$.
Aldous and Shields [AS] established it for the symmetric case.
In the asymmetric case the limiting distribution is unknown.
It is easy to derive a recurrence for $B_m^k$.
Define $B_m^k(u)=Eu^{B_m^k}$. Then
$$
B_{m+1}^k(u)=\sum_{l=0}^m {m \choose l} p^lq^{m-l} B_l^{k-1}(u)
B_{m-l}^{k-1}(u)~,
$$
with $B_0^0(u)=1$. Let now $B^k(z,u)=\sum_{m=0}^\infty B_m^k(u)
{z^m \over m!}$. Then, the above becomes
$$
{\partial B^k(z,u) \over \partial z} =
B^{k-1}(pz,u) B^{k-1}(qz,u)
$$
with $B^0(z,u)=u(e^z-1)+1$. We conjecture that for
$k=O(\log m)$ the limiting distribution of $B_m^k$ is normal.
The average profile was established in [LS]
Limiting Distribution of the Height.
Let $H_n^k$ denote the probability that the {\it height} in a DST
with $m$ nodes is smaller equal to $k$. Define
$H^k(z)=\sum_{m\geq 0} H_m^k {z^m \over m!}$. Then, one
easily see that for $k\geq 1$
$$
{d H^k(z) \over d z} = H^{k-1}(zp) H^{k-1}(zq)
$$
with $H^0(z)=1+z$. What is the limiting distribution of
the height? From [Pittel] we only know
that $H_m /\log m \to 1/\log (\min\{1/p, 1/q\})$
almost surely.
Ill give you half an hour...
Damn it, i just tried to cheat and put all that into google.......and my p.c just threw upOriginally posted by John C
Pinchy you are a hero.
Consider a digital search tree (DST) built over $m$
independently generated binary strings with ''$0$'' occurring with`
probability $p$ and ''$1$'' with probability
$q=1-p$.
Limiting Distribution of the Profile.
Let us fixed $k$ (that may depend on $m$), and define
$B_m^k$ as the number of nodes in the DST at level $k$.
This is called the profile of DST.
We are interested in obtaining the limiting distribution of
$B_m^k$ for any $k$.
Aldous and Shields [AS] established it for the symmetric case.
In the asymmetric case the limiting distribution is unknown.
It is easy to derive a recurrence for $B_m^k$.
Define $B_m^k(u)=Eu^{B_m^k}$. Then
$$
B_{m+1}^k(u)=\sum_{l=0}^m {m \choose l} p^lq^{m-l} B_l^{k-1}(u)
B_{m-l}^{k-1}(u)~,
$$
with $B_0^0(u)=1$. Let now $B^k(z,u)=\sum_{m=0}^\infty B_m^k(u)
{z^m \over m!}$. Then, the above becomes
$$
{\partial B^k(z,u) \over \partial z} =
B^{k-1}(pz,u) B^{k-1}(qz,u)
$$
with $B^0(z,u)=u(e^z-1)+1$. We conjecture that for
$k=O(\log m)$ the limiting distribution of $B_m^k$ is normal.
The average profile was established in [LS]
Limiting Distribution of the Height.
Let $H_n^k$ denote the probability that the {\it height} in a DST
with $m$ nodes is smaller equal to $k$. Define
$H^k(z)=\sum_{m\geq 0} H_m^k {z^m \over m!}$. Then, one
easily see that for $k\geq 1$
$$
{d H^k(z) \over d z} = H^{k-1}(zp) H^{k-1}(zq)
$$
with $H^0(z)=1+z$. What is the limiting distribution of
the height? From [Pittel] we only know
that $H_m /\log m \to 1/\log (\min\{1/p, 1/q\})$
almost surely.
Ill give you half an hour...