Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with
Search options not deleted user 54239

Enumerative combinatorics, graph theory, order theory, posets, matroids, designs and other discrete structures. It also includes algebraic, analytic and probabilistic combinatorics.

1 vote
0 answers
139 views

bounded degree graph colouring.

I was wondering if anyone could provide references on the following: Is determining the chromatic number of a bounded degree graph APX-complete? 2.I've seen the result that states it is NP-hard t …
Pavan Sangha's user avatar
3 votes
0 answers
180 views

Hypergraph edge colouring

I'm interested in knowing if finding the edge-chromatic number of a $k$-uniform $k$-partite hypergraph is NP-hard for $k\geq 3$ Could anyone provide a reference for the result? By edge-chromatic numbe …
Pavan Sangha's user avatar
0 votes
0 answers
61 views

Approximation to colouring for bounded degree graphs

I have already asked one question on colouring, this question is more specific. Given a bounded degree graph $G$ with $\Delta(G)=2d$, is there a well know algorithm to achieve an approximation ratio …
Pavan Sangha's user avatar
1 vote
1 answer
322 views

Graph colouring for bounded degree graphs

I'm fairly new to colourings on bounded degree graphs i'm interested in the following questions, For planar graphs with bounded degree $4$ is finding the colouring number $NP$-hard? So is essential …
Pavan Sangha's user avatar
2 votes
1 answer
93 views

Directed edge-colouring

I'm interested to know whether the following problem is NP-complete or if there is an algorithm to solve it. Suppose we are given a directed graph $G=(V,E^{\rightarrow})$ and we want to colour the e …
Pavan Sangha's user avatar
2 votes
1 answer
121 views

Orthogonal embeddings and edge lengths

I'm interested in orthogonal embeddings of graphs into the 2-dimensional, i.e where vertices are placed at integer co-ordinates and edges are routed along the grid lines and are not allowed to interse …
Pavan Sangha's user avatar
1 vote
0 answers
121 views

Building an orthogonal embedding for a 4-planar graph

I'm interested in the following paper http://www.computer.org/csdl/trans/tc/1981/02/06312176.pdf In particular i'm interested in the construction Valiant describes to prove that it is possible to em …
Pavan Sangha's user avatar
2 votes
1 answer
134 views

VLSI circuit embeddings

In the following paper by Valiant http://www.computer.org/csdl/trans/tc/1981/02/06312176.pdf He shows under theorem 2 (at the bottom of the second page) that any planar graph $G$ of degree 3 or 4 w …
Pavan Sangha's user avatar
3 votes
1 answer
213 views

Construction of planar embedding

I'm reading the following paper on universality considerations in VLSI circuits http://www.computer.org/csdl/trans/tc/1981/02/06312176.pdf In Theorem 2 On the second page it states there exists cons …
Pavan Sangha's user avatar
9 votes
3 answers
1k views

Embedding planar graphs into the grid

I've seen the following lemma in a paper. The result is by Valiant. A planar graph $G$ with maximum degree $4$ can be embedded in the plane using $O(|V|)$ area in such a way that its vertices are at …
Pavan Sangha's user avatar
6 votes
1 answer
200 views

Modification of matching

Suppose i have an $n \times n$ random bipartite graph and suppose that i repeat the following process $n$ times. At the start (stage 1) each edge is selected independently with probability $p(n)$, and …
Pavan Sangha's user avatar
0 votes
1 answer
811 views

Edge-disjoint cycles in graphs

Given a graph $G=(V,E)$ and a fixed integer $k$ are there any algorithms known which would find the maximum number of edge-disjoint cycles of length $k$ in $G$? If not is there a proof that this probl …
Pavan Sangha's user avatar
1 vote
0 answers
251 views

Multiple Bipartite graphs and matchings

I've been told recently that it's better i just for help regarding my 'specific' problem rather than lots of little questions around the same topic which appear somewhat unclear. I would first like to …
Pavan Sangha's user avatar
1 vote
2 answers
2k views

Expected matching in a bipartite graph

Consider a random bipartite graph constructed on vertex classes of size $n$ with each edge present independently with probability $p$. How could I go about calculating the size of the expected matchin …
Pavan Sangha's user avatar
3 votes
2 answers
466 views

Hamming graph and independent sets

I'm defining the Hamming graph $H(d,q)$ in the usual way, so we have a set $S$ of $q$ elements, the hamming graph $H(d,q)$ has vertex set $S^{d}$ (the set of all ordered $d$-tuples of elements of $S$) …
Pavan Sangha's user avatar

15 30 50 per page