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Topic: Exponential generating function


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In the News (Mon 16 Nov 09)

  
  "Glossary of Terms in Combinatorics"
Boolean function - function from subset lattice to {0,1} (False/True)
Characteristic polynomial \phi - 1) for a graph, the characteristic polynomial of the adjacency matrix (roots are the eigenvalues); 2) for a poset, the generating function of the Möbius function by co-rank
Möbius function - the inverse of \zeta in the incidence algebra, defined on intervals of P by \mu(x,x)=1 and \mu(x,y)=-\sum
www.math.uiuc.edu /~west/openp/gloss.html   (11773 words)

  
  Generating function - Wikipedia, the free encyclopedia
The particular generating function that is most useful in a given context will depend upon the nature of the sequence and the details of the problem being addressed.
Generating functions are often expressed in closed form as functions of a formal argument x.
The exponential generating function of a sequence a
en.wikipedia.org /wiki/Generating_function   (600 words)

  
 Generating function -- Facts, Info, and Encyclopedia article   (Site not responding. Last check: 2007-10-23)
is the (additional info and facts about probability mass function) probability mass function of a (additional info and facts about discrete random variable) discrete random variable, then its ordinary generating function is called a (additional info and facts about probability-generating function) probability-generating function.
Dirichlet series generating functions are especially useful for (additional info and facts about multiplicative function) multiplicative functions, when they have an (additional info and facts about Euler product) Euler product expression.
Generating functions for the sequence of (additional info and facts about square number) square numbers a
www.absoluteastronomy.com /encyclopedia/g/ge/generating_function.htm   (583 words)

  
 Symbolic Enumerative Combinatorics and Complex Asymptotic Analysis*
To avoid it, the crucial observation is that most of the generating functions that occur in combinatorial enumerations are also analytic functions: their expansions converge in a neighborhood of the origin and Cauchy's integral formula expresses Taylor coefficients of such analytic functions as contour integrals.
This section is dedicated to a short presentation of analytic functions, then to the determination of the exponential growth of the counting sequence, and finally to the subexponential factors.
If the location of the singularities of a function determines the exponential rate of growth of its coefficients, the nature of the singularities determines the way the dominant exponential term in coefficients is modulated by a subexponential factor.
algo.inria.fr /seminars/sem00-01/flajolet.html   (2980 words)

  
 Combinatorics   (Site not responding. Last check: 2007-10-23)
In some cases, a simple asymptotic function may be preferable to a horribly complicated closed formula that yields no insight to the behaviour of the counted objects.
Once determined, the generating function may allow one to extract all the information given by the previous approaches.
In addition, the various natural operations on generating functions such as addition, multiplication, differentiation, etc., have a combinatorial significance; and this allows one to extend results from one combinatorial problem in order to solve others.
www.sciencedaily.com /encyclopedia/combinatorics_1   (971 words)

  
 Wolfram Research, Inc.
and the exponential generating function of the constant sequence
This exponential generating function is simply the Taylor series for the exponential.
Here is the exponential generating function of the sequence of squares of integers.
documents.wolfram.com /v3/AddOns/DscM_RSolve-.html   (769 words)

  
 schroeder.html
We express that the function ceases to be differentiable at its singularity.
Random generation is easy and the experiments lead to new conjectures (like the degree distribution) and even theorems (like the analysis of the number of classification stages).
General observations of this type may be used to help distinguish classification trees without informational content ("random" trees) from meaningful ones.
algo.inria.fr /libraries/autocomb/schroeder-html/schroeder1.html   (1075 words)

  
 Transcendental Functions
In each of the functions below, the precision of the result will be approximately equal to the precision of the argument if that is finite; otherwise it will be approximately equal to the default precision of the parent of the argument.
We then create the denominator D = e^x - 1 of the exponential generating function to precision n + 2 (we need n + 2 since we lose precision when we divide by the denominator and the valuation changes).
We finally compute the Laplace transform of E (which multiplies the coefficient of x^i by i!) to yield the generating function of the Bernoulli numbers up to the x^n term.
www.math.lsu.edu /magma/text770.htm   (660 words)

  
 MathLinks Math Forum :: View topic - Dice   (Site not responding. Last check: 2007-10-23)
One is of the form :Sigma: a_i x^i which is the basic generating function, and another is of the form :Sigma: a_i x^i/i!, which is the exponential generating function.
I'd say generating functions is the way to go for these sorts of problems if the numbers aren't very small.
They key is not the value of the function for different values in domain, but the coefficient of x^k.
www.mathlinks.ro /Forum/post-39963.html   (951 words)

  
 6   (Site not responding. Last check: 2007-10-23)
(Assume a general form for the terms of the sequence, using the most obvious choice of such a sequence.) References I used: table 1 and the solutions manual number 3 for these problems.
For each of these generating functions, provide a closed formula for the sequence it determines.
What is the generating function for the sequence{c_k}, where c_k represents the number of ways to make change for k pesos using bills worth 10 pesos, 20 pesos, 50 pesos and 100 pesos?
home.hawaii.rr.com /nel/Ajimura_Janel.Week5.htm   (405 words)

  
 Math 3022   (Site not responding. Last check: 2007-10-23)
Use a generating function approach to answer the question of how many ways you can roll m dice, remove the lowest die, and obtain a total of n.
Once you have the knack of exponential generating functions you will see that they give a relatively easy way to solve these sorts of questions (although the first part should convince you that they are not always the right tool to use).
by counting the number of functions from a set of m elements to a set of n elements using exponential generating functions, but terminate the sums after m terms.
www.math.gatech.edu /~monteneg/3022/homework.html   (1324 words)

  
 Trucks, Convoys and Fleets
The reloading of (C,M) induced by f is a new reloaded truck (C',M') whose cargo manifest M' is the image of M under f, and whose cargo configuration C' is the graph C with any integer label n replaced by f(n).
Let c(n,k) be the number of convoys of total cargo capacity n made up of k trucks, each of which is a reloading of a truck in the fleet.
For the general case, compare coefficients on both sides of the equation and by examining any one particular coefficient argue that the finite case suffices.
www.math.toronto.edu /~jjchew/math/trucks.html   (834 words)

  
 321 Course Info S95
For problems #1-4, construct an appropriate exponential generating function, and calculate the desired coefficient without the aid of Maple.
Use an exponential generating function to find the number of ways to distribute n different objects into 5 different boxes so that there is an even number of objects in box #5.
Use an exponential generating function to find the number of ways to make a single stack of n poker chips (of three possible colors—red, white or blue) that contains an odd number of red chips and at least one blue chip.
people.uncw.edu /spackmank/mat375/375hw9.htm   (209 words)

  
 COCS5313TEST-1   (Site not responding. Last check: 2007-10-23)
Derive the generating function for the number of ways to pick a sample of k people, for k=0,1,2,3,4,5,...
The average-case algorithm analysis is, in general, more difficult as we need to account for all possible expected inputs without having to know their distribution probabilities, among others.
It is also the (regular) Generating function of the sequence, (C(n,k)), k=0,1,2,...,n.
hal.lamar.edu /~KOH/5313/5313T1.HTML   (624 words)

  
 Math Forum - Ask Dr. Math
prove that its exponential generating function is 1/sqrt(1-2*x).
Date: 05/06/2000 at 16:33:23 From: Doctor Anthony Subject: Re: Exponential Generating Functions Expand using the binomial theorem.
has coefficient: (1)(3)(5) and so this expansion is the exponential generating function for the series: 1, (1)(3), (1)(3)(5),...
mathforum.org /library/drmath/view/56964.html   (93 words)

  
 UMTYMP Advanced Topics – Introduction to Combinatorics
n!, we need to use an exponential generating function.
x = 0 and we will not be able to find a closed-form formula for the generating function.
The exponential generating function for the number of permutations is
www.math.umn.edu /~jhall/courses/2474/hw11sol.htm   (220 words)

  
 Table of Contents
Its approach blends combinatorial and algebraic ideas to offer insights into a wide variety of problems, and each section of the book focuses on a specific discrete structure, advancing from elementary (often classical) results to those at research level.
Subjects include the combinatorics of the ordinary generating function and the exponential generating function, the combinatorics of sequences, and the combinatorics of paths.
The Combinatorics of the Ordinary Generating Function 3.
www.doverpublications.com /cgi-bin/toc.pl/0486435970   (118 words)

  
 [No title]
More Illustrations and Applications THE "POSET CONJECTURE" Recall that OmegaGF[P,q] is the rational generating function for the order polynomial of P. Conjecture: For any poset P, the numerator of OmegaGF[p,q] has only real roots, and they are all negative.
These are the number whose exponential generating function is Tan[x] + Sec[x].
Done -Graphics- MaximalChainsDown[weaks4] {1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 2, 2, 1, 3, 3, 3, 2, 3, 5, 6, 5, 16} It turns out to be a theorem that, in general, the number of maximal chains in these two posets is the same.
www.haverford.edu /math/cgreene/pd/pd6more.html   (856 words)

  
 eishelp2.html
The ordinary generating function (G.f.) for a sequence a(0), a(1), a(2),...
Usually one can think of an ordinary generating function as a Taylor series, and extract the nth coefficient by differentiating A(x) n times, setting x = 0, and dividing by n!.
The exponential generating function (E.g.f.) for a sequence a(0), a(1), a(2),...
www.research.att.com /~njas/sequences/eishelp2.html   (1663 words)

  
 week190
The exponential generating function applies to structure types, and is defined as above.
It has many of the same nice properties as the exponential generating function, as long as we careful to adapt everything to the category D. You can read all about this in the book by Bergeron et al cited in "week185".
confusion), there are some formulas relating the exponential generating functions of the former to the ordinary generating functions of the latter.
math.ucr.edu /home/baez/week190.html   (3419 words)

  
 Exponential.html
Recall the moment generating function of a random variable
The moment generating function provides us alternative ways to calculate the mean and variance by way of the formula:
See, for example, Mathematical Statistics and Data Analysis by John A. Rice for more on the moment generating function.
www2.kenyon.edu /People/hartlaub/MellonProject/Exponential4.html   (125 words)

  
 [No title]   (Site not responding. Last check: 2007-10-23)
Prove that the sequence $a_n=S(n,k)$ has exponential generating function \[ \frac{1}{k!}\left(e^x-1\right)^k \] \noindent {\bf NOTE:} This one is difficult, I wouldn't recommend it.
\begin{itemize} \item[(a)] Prove that \[ S(n,k)=\frac{1}{k!}\sum_{i=0}^k(-1)^{k-i}{k\choose i}i^n \] (Yes, this is the same as another homework, but this time you must use exponential generating functions for your proof.) \item[(b)] Let $B(0), B(1), \ldots$ be the Bell numbers.
Prove the exponential generating function of $\{B(n)\}_{n=0}^{\infty}$ is \[ \exp\left(e^x-1\right)=e^{e^x-1}.
orion.math.iastate.edu /rymartin/CMU301/hw8.texx   (366 words)

  
 Citations: An Introduction to Combinatorial Analysis - Riordan (ResearchIndex)   (Site not responding. Last check: 2007-10-23)
Thus every theorem about Xi D can be specialized to a theorem in rook theory, and we can also try to generalize every theorem in rook theory to a theorem about Xi D.
....of the exponential integral Ei (x) and the incomplete gamma function (z;x) by A z = L[1; t 1 ] e(z 2) z 1; 1) 1) eEi (1) 1) 11 4.
, of which the exponential generating function is This and the exponential formula [18, 30] imply that fi Comparing the above identity with (2.
citeseer.ist.psu.edu /context/23602/0   (1651 words)

  
 Derangements and Generalizations
But then we need to subtract the number of arrangements that leave THREE objects unmoved, and so on.
The Encyclopedia of Integer Sequences (Sloane & Plouffe) lists the values up to D(17), and also notes the exponential generating function 1 inf x^n --------- = SUM D(n) --- (1-x) e^x n=0 n!
Now suppose that, instead of being given just a single arrangement of objects, we specify TWO arrangements (not necessarily distinct), and consider the number of permutations that have no object in the same position as it occupies in EITHER of the two given arrangements.
www.mathpages.com /home/kmath430.htm   (821 words)

  
 Problem Set 4   (Site not responding. Last check: 2007-10-23)
Use the Transfer Matrix Method to determine the generating function for the number of permutations
Define F(t) to be the ordinary generating function for rooted plane trees in which each vertex with i children is assigned the weight tz
Show that the exponential generating function for the number of distinct monomials that appear in the expansion of is
web.mit.edu /aram/www/math/315-web/node93.html   (294 words)

  
 [No title]
I f the balls are indistinguishable, then we simply regard them as anony mous unlabelled atoms (generically called " }{HYPERLNK 17 "Z" 2 "combs truct[specification]" "" }{TEXT -1 143 ", by a global convention of Co mbstruct).
The reason for doin g this is a simpler form of generating functions (as we do not have to go unnecessarily through Polya operators) as well as faster computati ons.
A molecule has \+ n modes, and I need to generate every possible combination which place s up to m quanta in each mode.
algo.inria.fr /libraries/autocomb/balls.mws   (1891 words)

  
 [No title]
… If a sequence has no zeroeth term, its generating function usually starts with constant term 0.
That is, if g(x) is the ordinary generating function for the sequence h_0, h_1, h_2, h_3, …, then g(cx) is the ordinary generating function for the sequence h_0, c h_1, c^2 h_2, c^3 h_3, ….
That is, if g(x) is the exponential generating function for the sequence h_0, h_1, h_2, h_3, …, then g(cx) is the exponential generating function for the sequence h_0, c h_1, c^2 h_2, c^3 h_3, ….
www.math.wisc.edu /~propp/475/Apr13.doc   (367 words)

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