implemented on the Pointer Machine in constant amortized time.
\proof
-We create a~``yardstick'' --- a~double linked list whose elements represent the possible
+We will recycle the idea of ``yardsticks'' from Section \ref{bucketsort}.
+We create a~yardstick --- a~doubly linked list whose elements represent the possible
values of a~rank. Every vertex of a~queue will store its rank as a~pointer to
the corresponding ``tick'' of the yardstick. We will extend the list as necessary.
The combined graph~$G_B$ has~$n$ vertices, but less than~$n$ edges from the
individual spanning trees and at most~$m/4$ additional edges which were
-corrupted. The iterations of the Bor\o{u}vka's algorithm on~$G_B$ take $\O(m)$
+corrupted. The Bor\o{u}vka steps on~$G_B$ take $\O(m)$
time by Lemma \ref{boruvkaiter} and they produce a~graph~$G_C$ with at most~$n/4$
vertices and at most $n/4 + m/4 \le m/2$ edges. (The $n$~tree edges in~$G_B$ are guaranteed
to be reduced by the Bor\o{u}vka's algorithm.) It is easy to verify that this