# Tagged Questions

The study of probability distributions over graphs. For example, the Erdős–Rényi model where each edge occurs independently with equal probability.

1answer
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### Length of longest directed circuit in random tournament

Build a random tournament $T=(V,E)$ on $V=\{1,\ldots, n\}$ in the following fashion: for $i < j\in \{1,\ldots, n\}$ let the probability be $0.5$ whether $(i,j)\in E$ or $(j,i)\in E$ (in a ...
0answers
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### Drawing graph with some different metric values [closed]

I have some metrics but all of them have different values. Some are decimals, some are integers and some are large numbers. Assume the metrics are (average values): - metric1 - 1500 - metric2 - 0....
1answer
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### Existence of a Connectivity Polynomial for a simple graph?

I try to find a polynomial for an arbitrary simple graph $G$ that tells whether the graph is connected or not. A graph is st-connected if you can find a path between a vertex $s$ and a vertex $t$ -- ...
1answer
287 views

### Question on a paper by Benjamini/Kozma/Wormald about a “well known fact”

In "The mixing time of the giant component of a random graph" by the aforementioned authors, in the last proof on page 19 it says something along the lines of "It is well known and easy to verify ...
0answers
66 views

### How are Polynomials of Toric ideals Studied with Exponents as ST-cuts?

Topic: Toric ideals on Expected value of Structure Functions in Random Graphs Goal: to understand the toric ideal where the exponents $h_i$ and $s_j$ are st-vertex-cuts of a digraph ...
0answers
81 views

### Fraction of vertices in ER random graphs not in giant or tiny components

ER random graphs in $G(n,m)$ model are known to have a giant component when $m>n/2$ which grows to a value of $\Theta(n)$ very abruptly. Also the size of the second largest component is known to ...
1answer
105 views

1answer
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### Random Walk 2D with dependent weights [closed]

I have spent a lot of time trying to solve this problem but have had no luck so far! Any help would be highly appreciated! Suppose I have a 3x3 grid as shown below. (3,1) (3,2) (3,3) (2,1) (2,2) (...
1answer
83 views

### Vertex cover of regular graph

(1.) How small can set $S$ of vertices in any regular undirected graph $G$ on $n$ vertices with degree $\Omega(n^\alpha)$ where $\alpha\in(0,1)$ can be such that every edge in the graph is incident on ...
0answers
39 views

### Critical probability, bond percolation on triangular lattice

Let G a graph and $p_c(G)$ the critical probability of bond percolation. Let G be a triangular lattice then $p_c(G) = 2\sin(\frac{\pi}{18})$ (Grimmett, Percolation p.65). Ramanujan find this formula : ...
0answers
114 views

### Ramanujan graphs and stable real polynomials

I have a problem with the lemma 6.5 and the theorems 5.1, 6.6 in the paper of Adam Marcus, Daniel Spielman and Nikhil Srivastava. http://arxiv.org/pdf/1304.4132.pdf I do not understand how they use ...
2answers
158 views

### first order languages over graphs (and other discrete models)

A lot of research has been devoted to the study of first order language of graphs (FO). Formulas in this language are constructed using variables $x, y,\dots$ ranging over the vertices of a graph, the ...
1answer
155 views

### Proofs of inequalities used by Erdos-Renyi in their Random Graphs Paper 1

Please refer to this, it is Erdos-Renyi 1959 paper 1 on Random Graphs. I am currently working on this, but I am stuck on the fifth page, where they use two estimates. More specifically, here's the ...
3answers
137 views

### Repository of graph classes that are tough to test non-isomorphic pairs from isomorphic pairs

(1) Which graph classes are extremely tough to test for graph non-isomorphic pairs from isomorphic pairs? (2) Is there a repository of adjacencies from such classes?
2answers
160 views

### Database of adjacency matrices on cospectral non-isomorphic graph pairs

Is there a repository of cospectral non-isomorphic graphs available somewhere? I am looking for list of $0/1$ adjacency matrix pairs that can be input data in tools such as MATLAB.
0answers
127 views

### In a random graph which one is more probable, $k$-clique or $k$-core?

Recall that the $k$-core of a graph $G$ is the unique maximal subgraph of $G$ with minimum degree at least $k$. In an Erdos-Renyi random graph, where the edge selection is independent with ...
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58 views

### What is the gap between the two defined distances from node to node in a random graph?

Give a sparse random graph $G=(V,E)$, every edge $(u,v)\in E$ is associated with a weight $w(u,v)$. We assume each $w(u,v)$ is geometrically distributed with parameter $p_{u,v}$. The weight of a path ...
0answers
138 views

### Edit distance vs. canonical adjacency matrix distance

Let $G$ and $G'$ be two simple random graphs on the same set of nodes. Let $d_{edit}$ be the edit distance between $G$ and $G'$. Let $\mathbf{A}$ and $\mathbf{A'}$ be the adjacency matrices of the ...
0answers
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### Full distribution of FPTs in random walks on graphs

There is a lot of published research on the mean passage passage time (FPT) for random walks on various types of graphs. How about the variance of the FPT and higher momenta? In fact, I would be ...
1answer
171 views

### Number of nodes in a given distance in (random) regular graph

Given a d-regular graph $G=<V,E>$ (connected, unweighted & simple), and a node $v$. denote all nodes with distance $k$ from $v$ $$L_k=\{u\in V : dis(v,u) = k\}$$ Let's call it "the k-th ...
1answer
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### Independent Sets in random geometric graphs

I was wondering if a lot is known about independent sets in Random Geometric graphs? Most google searches don't bring up much. In addition I'm interested in any algorithms used for finding independent ...