Department of Mathematics Elementary Graph Theory Lecture 3
Subgraphs
A subgraph of G is a graph having all of its vertices and edges in G. If G1 is a
subgraph of G, then G is a supergraph of G1.
G1 is a subgraph of G
In other words.
If G and H are two graphs with vertex sets V(H), V(G) and edge sets E(H)
and E(G) respectively such that V(H) V(G) and E(H) E(G) then we call H as a
subgraph of G or G is a supergraph of H.
1. Spanning subgraph
A spanning subgraph is a subgraph containing all the vertices of G ( if
V(H) V(G) ) then we say that H is a spanning subgraph of G ).
The graphs F1 and H1 are spanning subgraphs of a graph G1, but J1 is not a
spanning subgraph of G1.
2. Removal of a vertex and an edge
The removal of a vertex vi from a graph G result is that subgraph G – vi of G
containing of all vertices in G except vi and all edges not incident with vi .
Dr. Didar A. Ali 1
, Department of Mathematics Elementary Graph Theory Lecture 3
Thus G – vi is the maximal subgraph of G not containing vi .
On the otherhand, the removal of an edge xi from G yields the spanning
subgraph G – xi containing all edges of G except xi . Thus G – xi is the
maximal subgraph of G not containing xi .
The addition of an edge vi v j to a graph G is G vi v j where vi and v j are
non-adjacent in G.
Deleting vertices from a graph G.
Deleting edges from a graph G
Dr. Didar A. Ali 2
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller bilal-guma. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $2.99. You're not tied to anything after your purchase.