The edges $F$ and $G$ have opposite labels.
The vertex $F$ has label 1.
The point $F$ is labelled 1. [Or: labelled by 1.]
We may assume after passing to a subsequence (still labelled $v_n$) that ......
Go to the list of words starting with: a
b
c
d
e
f
g
h
i
j
k
l
m
n
o
p
q
r
s
t
u
v
w
y
z