Diane Donovan

Critical sets in back circulant latin squares

SummaryTo date very few families of critical sets for latin squares are known. In this paper a new family of critical sets for back circulant latin squares is identified. The proof that each element of the critical set is an essential part of the reconstruction process relies on the proof of the existence of a large number of latin interchanges.

3-Homogeneous latin trades

Let T be a partial latin square and I be a latin square with T ⊆ L. We say that T is a latin trade if there exists a partial latin square T′ with T′ ∩ T = 0 such that (L\T) ∪ T′ is a latin square. A k-homogeneous latin trade is one which intersects each row, each column and each entry either 0 or k times. In this paper, we construct 4-homogeneous latin trades from rectangular packings of the plane with circles.

Closing the feedback loop: engaging students in large first-year mathematics test revision sessions using pen-enabled screens

How can active learning, peer learning and prompt feedback be achieved in large first-year mathematics classes? Further, what technologies may support these aims? In this article, we assert that test revision sessions in first-year mathematics held in a technology-enhanced lecture theatre can be highly interactive with students solving problems, learning from each other and receiving immediate feedback. This is facilitated by pen-enabled screens and synchronization software. We argue that the educational benefits achievable through the technology do outweigh the technological distractions, and that these benefits can be achieved by focused, targeted one-off sessions and not only by a semester-long, regular approach. Repeat mid-semester test revision sessions were offered on a non-compulsory basis using pen-enabled screens for all students. Students worked practice test questions and marked solutions to mathematical problems on the screens. Students’ work was then displayed anonymously for their peers to see. Answers were discussed with the whole class. We discuss outcomes from two offerings of these sessions using student feedback and lecturer reflections and show the impact of participation on self-reported student confidence. Pedagogical approaches that the technology allowed for the first time in a large class are highlighted. Students responded uniformly positively.

Populations of models, experimental designs and coverage of parameter space by Latin Hypercube and Orthogonal sampling

In this paper we have used simulations to make a conjecture about the coverage of a t-dimensional subspace of a d-dimensional parameter space of size n when performing k trials of Latin Hypercube sampling. This takes the form P(k,n,d,t) = 1 - e^(-k/n^(t-1)). We suggest that this coverage formula is independent of d and this allows us to make connections between building Populations of Models and Experimental Designs. We also show that Orthogonal sampling is superior to Latin Hypercube sampling in terms of allowing a more uniform coverage of the t-dimensional subspace at the sub-block size level. These ideas have particular relevance when attempting to perform uncertainty quantification and sensitivity analyses.

On the distance between distinct group Latin squares

In an article in 1992, Drapal addressed the question of how far apart the multiplication tables of two groups can be? In this article we continue this investigation; in particular, we study the interaction between partial equalities in the multiplication tables of the two groups and their subgroup structure

Professional development for teaching in higher education

Due to the changing nature of learning and teaching in universities, there is a growing need for professional development for lecturers and tutors teaching in disciplines in the mathematical sciences. Mathematics teaching staff receive some training in learning and teaching but many of the courses running at university level are not tailored to the mathematical sciences. This article reports on a collaborative research project aimed at investigating the type of professional development that Australian tertiary mathematics teachers need and their preference for delivery modes. Effective teaching promotes effective learning in our students and discipline-specific professional development will enhance outcomes for teachers, students, and mathematics.

Steiner Trades That Give Rise To Completely Decomposable Latin Interchanges

In this paper we focus on the representation of Steiner trades of volume less than or equal to nine and identify those for which the associated partial latin square can be decomposed into six disjoint latin interchanges.

Single laws for sloops and squags

Abstract We give single laws for the variety of all sloops and the variety of all squags.

Mutually orthogonal Latin squares and mutually unbiased bases in dimensions of odd prime power

There has been much interest in mutually unbiased bases (MUBs) and their connections with various other discrete structures, such as projective planes, mutually orthogonal Latin squares (MOLS) etc. It has been conjectured by Saniga et al. (J Opt B Quantum Semiclass Opt 6:L19–L20, 2004) that the existence of a complete set of MUBs in ℂd is linked to the existence of a complete set of MOLS of side length d. Since more is known about MOLS than about MUBs, most research has concentrated on constructing MUBs from MOLS (Roy and Scott, J Math Phys 48:072110, 2007; Paterek et al., Phys Rev A 70:012109, 2009). This paper gives a simple algebraic construction of MOLS from two known constructions of MUBs in the odd prime power case.

On Defining Sets of Full Designs with Block Size Three

A defining set of a t-(v, k, λ) design is a subcollection of its blocks which is contained in no other t-design with the given parameters, on the same point set. A minimal defining set is a defining set, none of whose proper subcollections is a defining set. The spectrum of minimal defining sets of a design D is the set {|M| | M is a minimal defining set of D}. We show that if a t-(v, k, λ) design D is contained in a design F, then for every minimal defining set dD of D there exists a minimal defining set dF of F such that