A copy of this issue can also be found on the
MetaPress server (with DOI names of articles).
Artur Korni{\l}owicz.
Cayley's Theorem,
Formalized Mathematics 19(4),
pages 223-225, 2011. MML Identifier:
CAYLEY Summary:
The article formalizes the Cayley's theorem saying that every group $G$ is
isomorphic to a subgroup of the symmetric group on $G$.
Peter Jaeger.
{B}orel-{C}antelli Lemma,
Formalized Mathematics 19(4),
pages 227-232, 2011. MML Identifier:
BOR_CANT Summary:
This article is about the Borel-Cantelli Lemma in probability theory.
Necessary definitions and theorems are
given in \cite{klenke:2006}
and \cite{georgii:2004}.
Keiko Narita, Artur Kornilowicz, Yasunari Shidama.
More on the Continuity of Real Functions,
Formalized Mathematics 19(4),
pages 233-239, 2011. MML Identifier:
NFCONT_4 Summary:
In this article we demonstrate basic properties of the continuous functions
from $\mathbb{R}$ to ${\cal R}^{n}$
which correspond to state space equations in control engineering.
Grzegorz Bancerek.
Representation Theorem for Stacks,
Formalized Mathematics 19(4),
pages 241-250, 2011. MML Identifier:
STACKS_1 Summary:
In the paper the concept of stacks is formalized.
As the main result the Theorem of Representation
for Stacks is given. Formalization is done according to \cite{Salwicki}.