Projects per year

## Personal profile

### Biography

**The puzzling mathematician **

They say Sudoku puzzles require no mathematics to solve. Australian Mathematical Society 2009 medal winner Dr Ian Wanless disagrees. He views Sudoku as an example of a branch of mathematics called combinatorics. Its outstanding feature is Sunday-afternoon surface simplicity. But mathematical solutions to these puzzles hold surprising conceptual depth and applications in information and communication technology (ICT).

Dr Wanless has always loved solving puzzles and the field of combinatorics mathematics allows him to do just that. The problems he solves resemble those found in puzzle books, including anagrams and crosswords. They tend to involve permutations, combinations and rearrangement of symbols.

Much of the motivation for studying combinatorics comes from ICT and includes applications such as coding mobile phone signals or writing music on a CD. Ultimately, this is where a lot of his work finds application. Personally, he is not interested in applying his solutions.

'I like the problems for their elegance as an intellectual puzzle,' Ian says. The problems he finds most attractive are those that can be stated so simply that a child can understand them. Yet some deep mathematics are needed to arrive at a solution that works for every permutation.

The classic combinatorics example is the four-colour map problem. The problem seems simple. It asks how many colours are needed to colour regions on a map so that no two adjacent regions have the same colour. It was posed in the 19th century but took more than 100 years to solve.

'As mathematicians we are trying to find universal, absolute solutions, with the added bonus that nobody has done it before. You need an inescapable reason why whatever example of a puzzle you tried, the solution you propose would always work.

'A mathematical argument has to be general and cover every contingency,' he says. 'That is the idea of proof and it is very important. Certain things that appear to be obvious can be extremely difficult to prove.'

His current favourite questions deal with Latin squares. A finished Sudoku puzzle is an example of a Latin square. These are problems in which symbols fit in a matrix and each symbol occurs once in each row and column.

'Latin squares arise in the design of statistical experiments in agriculture and psychology,' Ian says. 'They are used to decide in which order to do experiments and they are useful in designing code for communication. I'm interested in basic properties like how many there are. Again, they are problems you can explain to a child yet some tricky math is needed to solve them.'

Contrary to stereotypes of the lone wolf intellectual, Ian enjoys collaborating. He has a dozen projects in the works, many involving colleagues in the US, Europe and Asia.

'I'm very much of the opinion that mathematics is a team sport,' he says. 'I do write papers on my own. But it is more fun to collaborate. A lot of the best projects come from cross-fertilisation from different branches, as is the case in all science. You get surprising results when working between fields rather than in a field.'

### Research area keywords

- Latin Squares
- Combinatorial Designs
- Combinatorial Enumeration
- Matrix Permanents
- Graph Theory

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Network
Recent external collaboration on country level. Dive into details by clicking on the dots.

## Projects

## Matchings in Combinatorial Structures

Wanless, I., Bryant, D. & Horsley, D.

Australian Research Council (ARC), Monash University, University of Queensland , University of Melbourne

1/01/15 → 10/10/20

Project: Research

## Towards the prime power conjecture

Australian Research Council (ARC), Monash University

27/02/12 → 31/12/16

Project: Research

## Extremal Problems in Hypergraph Matchings

Wanless, I., Greenhill, C. & Aharoni, R.

Australian Research Council (ARC), University of New South Wales

3/01/12 → 31/12/14

Project: Research

## Permanents, permutations and polynomials

Wanless, I. & McKay, B.

Australian Research Council (ARC), Monash University, Australian National University

4/01/10 → 31/12/13

Project: Research

## Research Output

## Covering radius in the Hamming permutation space

Hendrey, K. & Wanless, I. M., 1 Feb 2020, In : European Journal of Combinatorics. 84, p. 1-9 9 p., 103025.Research output: Contribution to journal › Article › Research › peer-review

## Multidimensional permanents of polystochastic matrices

Child, B. & Wanless, I. M., 1 Feb 2020, In : Linear Algebra and Its Applications. 586, p. 89-102 14 p.Research output: Contribution to journal › Article › Research › peer-review

## Perfect 1-factorisations of *K*_{16}

Gill, M. J. & Wanless, I. A. N. M., Apr 2020, In : Bulletin of the Australian Mathematical Society. 101, 2, p. 177-185 9 p.Research output: Contribution to journal › Article › Research › peer-review

## Covers and partial transversals of Latin squares

Best, D., Marbach, T., Stones, R. J. & Wanless, I. M., 2019, In : Designs Codes and Cryptography. 87, 5, p. 1109-1136 28 p.Research output: Contribution to journal › Article › Research › peer-review

## The existence of square integer Heffter arrays

Dinitz, J. H. & Wanless, I. M., 1 Jan 2019, In : Ars Mathematica Contemporanea. 16, 1, p. 81-93 13 p.Research output: Contribution to journal › Article › Research › peer-review