11
9
MSO
•
Two problems:
•
•
Connectivity
: given a graph G, is it fully
connected ?
•
Reachability
: given a graph G and two constants
s, t, is there a path from s to t ?
•
•
Both are expressible in
8
MSO
[
how ??? ]
•
But are they expressible in
9
MSO ?