1. CJM Online first
 Dyer, Matthew

On the weak order of Coxeter groups
This paper provides some evidence for conjectural
relations between extensions of (right) weak order on Coxeter
groups, closure operators on root systems, and Bruhat order.
The conjecture
focused upon here refines an earlier question as to whether the
set of initial sections of reflection orders, ordered by inclusion,
forms a complete lattice.
Meet and join in weak order are described in terms of a suitable
closure operator. Galois connections are defined from the
power set of $W$ to itself, under which maximal subgroups of
certain groupoids correspond
to certain complete meet subsemilattices of weak order. An analogue
of weak order for standard parabolic subsets of any rank
of the root system
is defined, reducing to the usual weak order in rank zero, and
having some analogous properties in rank one (and conjecturally
in general).
Keywords:Coxeter group, root system, weak order, lattice Categories:20F55, 06B23, 17B22 

2. CJM Online first
 Handelman, David

Nearly approximate transitivity (AT) for circulant matrices
By previous work of Giordano and the author, ergodic
actions of $\mathbf Z$ (and other discrete groups) are completely classified
measuretheoretically by their dimension space, a construction
analogous to the dimension group used in C*algebras and topological
dynamics. Here we investigate how far from AT (approximately
transitive) can actions be which derive from circulant (and related)
matrices. It turns out not very: although nonAT actions can
arise from this method of construction, under very modest additional
conditions, ATness arises; in addition, if we drop the positivity
requirement in the isomorphism of dimension spaces, then all
these ergodic actions satisfy an analogue of AT. Many examples
are provided.
Keywords:approximately transitive, ergodic transformation, circulant matrix, hemicirculant matrix, dimension space, matrixvalued random walk Categories:37A05, 06F25, 28D05, 46B40, 60G50 

3. CJM 2017 (vol 70 pp. 26)
 Bosa, Joan; Petzka, Henning

Comparison Properties of the Cuntz semigroup and applications to C*algebras
We study comparison properties in the category $\mathrm{Cu}$ aiming to
lift results to the C*algebraic setting. We introduce a new
comparison property and relate it to both the CFP and $\omega$comparison.
We show differences of all properties by providing examples,
which suggest that the corona factorization for C*algebras might
allow for both finite and infinite projections. In addition,
we show that R{\o}rdam's simple, nuclear C*algebra with a finite
and an infinite projection does not have the CFP.
Keywords:classification of C*algebras, cuntz semigroup Categories:46L35, 06F05, 46L05, 19K14 

4. CJM 2015 (vol 68 pp. 675)
 MartínezdelaVega, Veronica; Mouron, Christopher

Monotone Classes of Dendrites
Continua $X$ and $Y$ are monotone equivalent
if there exist monotone onto maps $f:X\longrightarrow Y$ and
$g:Y\longrightarrow X$. A continuum $X$ is isolated with respect
to monotone maps if every continuum that is monotone equivalent
to $X$ must also be homeomorphic to
$X$. In this paper we show that a dendrite $X$ is isolated with
respect to
monotone maps if and only if the set of ramification points of
$X$ is
finite. In this way we fully characterize the classes of dendrites
that are
monotone isolated.
Keywords:dendrite, monotone, bqo, antichain Categories:54F50, 54C10, 06A07, 54F15, 54F65, 03E15 

5. CJM 2010 (vol 62 pp. 758)
 Dolinar, Gregor; Kuzma, Bojan

General Preservers of QuasiCommutativity
Let ${ M}_n$ be the algebra of all $n \times n$ matrices over $\mathbb{C}$. We say that $A, B \in { M}_n$ quasicommute if there exists a nonzero $\xi \in \mathbb{C}$ such that $AB = \xi BA$. In the paper we classify bijective not necessarily linear maps $\Phi \colon M_n \to M_n$ which preserve quasicommutativity in both directions.
Keywords:general preservers, matrix algebra, quasicommutativity Categories:15A04, 15A27, 06A99 

6. CJM 2003 (vol 55 pp. 3)
 Baake, Michael; Baake, Ellen

An Exactly Solved Model for Mutation, Recombination and Selection
It is well known that rather general mutationrecombination models can be
solved algorithmically (though not in closed form) by means of Haldane
linearization. The price to be paid is that one has to work with a
multiple tensor product of the state space one started from.
Here, we present a relevant subclass of such models, in continuous time,
with independent mutation events at the sites, and crossover events
between them. It admits a closed solution of the corresponding
differential equation on the basis of the original state space, and
also closed expressions for the linkage disequilibria, derived by means
of M\"obius inversion. As an extra benefit, the approach can be extended
to a model with selection of additive type across sites. We also derive
a necessary and sufficient criterion for the mean fitness to be a Lyapunov
function and determine the asymptotic behaviour of the solutions.
Keywords:population genetics, recombination, nonlinear $\ODE$s, measurevalued dynamical systems, MÃ¶bius inversion Categories:92D10, 34L30, 37N30, 06A07, 60J25 

7. CJM 2002 (vol 54 pp. 757)
 Larose, Benoit

Strongly Projective Graphs
We introduce the notion of strongly projective graph, and characterise
these graphs in terms of their neighbourhood poset. We describe certain
exponential graphs associated to complete graphs and odd cycles. We
extend and generalise a result of Greenwell and Lov\'asz \cite{GreLov}:
if a connected graph $G$ does not admit a homomorphism to $K$, where $K$
is an odd cycle or a complete graph on at least 3 vertices, then the
graph $G \times K^s$ admits, up to automorphisms of $K$, exactly $s$
homomorphisms to $K$.
Categories:05C15, 06A99 

8. CJM 2001 (vol 53 pp. 592)
 Perera, Francesc

Ideal Structure of Multiplier Algebras of Simple $C^*$algebras With Real Rank Zero
We give a description of the monoid of Murrayvon Neumann equivalence
classes of projections for multiplier algebras of a wide class of
$\sigma$unital simple $C^\ast$algebras $A$ with real rank zero and stable
rank one. The lattice of ideals of this monoid, which is known to be
crucial for understanding the ideal structure of the multiplier
algebra $\mul$, is therefore analyzed. In important cases it is shown
that, if $A$ has finite scale then the quotient of $\mul$ modulo any
closed ideal $I$ that properly contains $A$ has stable rank one. The
intricacy of the ideal structure of $\mul$ is reflected in the fact
that $\mul$ can have uncountably many different quotients, each one
having uncountably many closed ideals forming a chain with respect to
inclusion.
Keywords:$C^\ast$algebra, multiplier algebra, real rank zero, stable rank, refinement monoid Categories:46L05, 46L80, 06F05 

9. CJM 1999 (vol 51 pp. 792)
 Grätzer, G.; Wehrung, F.

Tensor Products and Transferability of Semilattices
In general, the tensor product, $A \otimes B$, of the lattices $A$ and
$B$ with zero is not a lattice (it is only a joinsemilattice with
zero). If $A\otimes B$ is a {\it capped\/} tensor product, then
$A\otimes B$ is a lattice (the converse is not known). In this paper, we
investigate lattices $A$ with zero enjoying the property that $A\otimes
B$ is a capped tensor product, for {\it every\/} lattice $B$ with zero;
we shall call such lattices {\it amenable}.
The first author introduced in 1966 the concept of a {\it sharply
transferable lattice}. In 1972, H.~Gaskill defined,
similarly, sharply transferable semilattices, and characterized them
by a very effective condition (T).
We prove that {\it a finite lattice $A$ is\/} amenable {\it if{}f it is\/}
sharply transferable {\it as a joinsemilattice}.
For a general lattice $A$ with zero, we obtain the result: {\it $A$ is
amenable if{}f $A$ is locally finite and every finite sublattice of $A$
is transferable as a joinsemilattice}.
This yields, for example, that a finite lattice $A$ is amenable
if{}f $A\otimes\FL(3)$ is a lattice if{}f $A$ satisfies (T), with
respect to join. In particular, $M_3\otimes\FL(3)$ is not a lattice.
This solves a problem raised by R.~W.~Quackenbush in 1985 whether
the tensor product of lattices with zero is always a lattice.
Keywords:tensor product, semilattice, lattice, transferability, minimal pair, capped Categories:06B05, 06B15 
