Introduction to Random Graphs Flashcards

1
Q

graph

A

pair of vertex set and edge set

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2
Q

complete graph

A

n vertices and all possible edges

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3
Q

subgraph

A

subset of vertices and subset of edges

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4
Q

G(n,p) Erdos-Renyi random graph

A

random spanning subgraph of Kn
P(E(G(n,p))=s)=p^s(1-p)^{{n choose 2} - s}

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5
Q

connected

A

there is a path between any pair of vertices
//one component

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6
Q

cycle

A

sequence of distinct vertices and there is edge v_n to v_1

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7
Q

occurs with high probability

A

lim P(A_n) =1 as n tends to infinity

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8
Q

neighbour

A

(v,w) in E

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9
Q

edges in complete

A

n choose 2

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10
Q

spanning subgraph

A

V’=V

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11
Q

tree

A

connected graph with no cycles

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12
Q

component

A

maximal connected subgraph

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13
Q

Cayley’s formula/number of trees on n vertices

A

n^{n-2}

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14
Q

a_n=o(b_n)

A

a_n/b_n tends to 0 as n tends to infinity

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15
Q

a_n=O(b_n)

A

there exists C such that a_n =< Cb_n for all n

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16
Q

a_n ~ b_n

A

lim (a_n/b_n)=1

17
Q

a_n«b_n

A

a_n=o(b_n)

18
Q

a_n»b_n

A

b_n=o(a_n)

19
Q

a_n=Θ(b_n)

A

a_n=O(b_n) and b_n=O(a_n)

20
Q

union bound

A

P(unions)<=sum of Ps

21
Q

expectation

A

sum of xP(X=x)

22
Q

Var(X)

A

E(X^2)-E(X)^2

23
Q

covariance

A

E(XY)-E(X)E(Y)

24
Q

markov’s inequality

A

nonnegative RV, t>0
P[X>=t]<=E[X]/t

25
Q

tends to x in probability

A

for all ε |X_n-x|<ε with high probability//
lim P[|X_n-x|>=ε]=0

26
Q

branching process with offspring distribution q

A

sequence of RVs taking values in NN_0 representing the sizes of successive generations when each individual independently has k offspring with probability q_k

27
Q

total size

A

sum of Zs

28
Q

survives

A

if T = inf

29
Q

extinction occurs

A

T<inf