The test will consist of definitions, examples, algorithms, and proofs,
in some combination
which seems possible to do in 75 minutes.
This is more like a reminder of what we've done than a review sheet...but
anyway here it is.
I'm just going to list some things. First, terms you should know
how to define and use in a
sentence; second, the major theorems and facts that we've discussed;
and third, algorithms
that you should be able to execute.
Terms you should know: this is a long list. At the beginning,
most of them are completely
straightforward. There are some, however, which are more conceptual.
You might have
different opinions about which ones, but the ones that I thought required
some thinking to
digest I marked with a *.
Graph, vertex, edge, adjacent, incident
Multiple edge, loop, simple graph
Degree, end-vertex, isolated vertex, degree sequence
*Isomorphism: this is a kind of function
*Isomorphic: a relation which may or may not hold
between TWO graphs
(the sentence "G is isomorphic"
makes no sense)
Connected graph, connected components of a graph
Subgraph, G-v, G-e, G\e
*Complement of a graph
Adjacency matrix
Path graph, cycle graph
*Bipartite graph
Complete graph, complete bipartite graph
Cube graph
Regular graph
Platonic graphs, Petersen graph
*Walk, length of a walk, trail, path, cycle
Cutset, bridge, *edge-connectivity
Separating set, cut-vertex, *vertex-connectivity
*Eulerian and semi-Eulerian graphs: remember the difference
between the definition and
the theorem...the definition
is that there's a certain kind of trail in the graph
*Hamiltonian and semi-Hamiltonian graphs
Tree, forest
*Spanning tree of a graph
*Planar graph, planar drawing of a graph
*Homeomorphism, contraction: think of each of these
as a process
*Homeomorphic, contractible: relations which may
or may not hold between TWO graphs
Note that if G and H are
homeomorphic, then H and G are homeomorphic. HOWEVER,
If G is contractible to
H, it does not mean that H is contractible to G.
*Genus of a graph
Crossing number of a graph
Major theorems and facts you should know how to prove:
The handshaking lemma
A graph is bipartite if and only if all its cycles
have even length
A graph is Eulerian if and only if all its vertices
have even degree (This isn't a definition, it's
a theorem)
A graph is semi-Eulerian if and only if exactly
two vertices have odd degree (same here)
Ore's theorem: a sufficient condition for
a graph to be Hamiltonian
Various characterizations of trees: see Theorem
9.1 in the book
How many labeled trees on n vertices are there?
n(n-2)
A graph is planar if and only if it contains no
subgraph homeomorphic to K5 or K3,3
Above is true if "homeomorphic" is replaced by "contractible"
Euler's formula: v-e+f=2 for any planar drawing
of a connected (planar) graph
Euler's formula for surfaces: v-e+f=2-2g (where
g is the genus)
For any graph G, its genus is less than or equal
to its crossing number
There are only five Platonic solids
Algorithms you should be able to implement:
Given an Eulerian graph, find an Eulerian cycle
In a weighted graph, find the shortest path from
one vertex to another
The Chinese postman problem: find the shortest
walk which uses every edge at least once
You should be able to do
this in some simple cases
The travelling salesman problem: find the
shortest path which uses every vertex at least once
Again, you should be able
to do this in some simple cases
Given a weighted graph, find a minimal weight spanning
tree (the greedy algorithm works)
I think that's about it. There are some minor lemmas too, like
the one that says that if a graph has
no vertices of degree 1 then it must contain a cycle, and things like
that.