diff --git a/year4/semester2/CS4423/assignments/assignment2/CS4423-HW2-1-tutorial.pdf b/year4/semester2/CS4423/assignments/assignment2/CS4423-HW2-1-tutorial.pdf new file mode 100644 index 00000000..e36eda08 Binary files /dev/null and b/year4/semester2/CS4423/assignments/assignment2/CS4423-HW2-1-tutorial.pdf differ diff --git a/year4/semester2/CS4423/assignments/assignment2/CS4423-HW2-1.pdf b/year4/semester2/CS4423/assignments/assignment2/CS4423-HW2-1.pdf new file mode 100644 index 00000000..1656f1c9 Binary files /dev/null and b/year4/semester2/CS4423/assignments/assignment2/CS4423-HW2-1.pdf differ diff --git a/year4/semester2/CS4423/materials/CS4423-W09-Part-2.pdf b/year4/semester2/CS4423/materials/CS4423-W09-Part-2.pdf new file mode 100644 index 00000000..ba431095 Binary files /dev/null and b/year4/semester2/CS4423/materials/CS4423-W09-Part-2.pdf differ diff --git a/year4/semester2/CS4423/notes/CS4423.pdf b/year4/semester2/CS4423/notes/CS4423.pdf index 957ad04a..8d273f8f 100644 Binary files a/year4/semester2/CS4423/notes/CS4423.pdf and b/year4/semester2/CS4423/notes/CS4423.pdf differ diff --git a/year4/semester2/CS4423/notes/CS4423.tex b/year4/semester2/CS4423/notes/CS4423.tex index cb31f731..6abf5bac 100644 --- a/year4/semester2/CS4423/notes/CS4423.tex +++ b/year4/semester2/CS4423/notes/CS4423.tex @@ -1078,7 +1078,19 @@ Also, the \textbf{average degree} of a randomly chosen node is \langle k \rangle = \sum^{n-1}_{k=0} kp_k = p(n-1) \end{align*} -(with standard deviation $\sigma_k = \sqrt{p(1-p)(n-1))}. +(with standard deviation $\sigma_k = \sqrt{p(1-p)(n-1))}$. +\\\\ +In general, it is not so easy to compute +\[ + \binom(n-1)(k) p^k (1-p)^{n-1-k} +\] + +However, in the limit $n \to \infty$ with $\langle k \rangle k = p(n-1)$ kept constant, the binomial distribution $\text{bin}(n-1,p,k)$ is well-approximated by the \textbf{Poisson distribution}: +\[ + p_k = e^{-\lambda} \frac{\lambda^k}{k!} = \text{Pois}(\lambda, k) +\] + +where $\lambda = p(n-1)$.