Department of Mathematics and Statistics
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COVID19’s Second Wave: How are teachers faring with the return to physical schools?
(Canadian Education Network, 20201120) 
Opportunity solving: Ordinary people doing extraordinary things, every day
(Canadian Education Network, 20201016) 
It’s okay to be okay too. Why calling out teachers’ “toxic positivity” may backfire
(Canadian Education Network, 2020) 
Canadian teachers' attitudes toward change, efficacy, and burnout during the COVID19 pandemic
(Elsevier, 20201119)Canadian teachers (N = 1626) took part in a longitudinal, national survey conducted at two points early in the COVID19 pandemic. Results indicated that teacher efficacy, attitudes toward change, and perceptions of ... 
Characterization of the lengths of binary circular words containing no squares other than 00, 11, and 0101
(20200519)We characterize exactly the lengths of binary circular words containing no squares other than 00, 11, and 0101. 
On avoidability of formulas with reversal
(EDP Sciences, 20180213)While a characterization of unavoidable formulas (without reversal) is wellknown, little is known about the avoidability of formulas with reversal in general. In this article, we characterize the unavoidable formulas ... 
Squares and overlaps in the ThueMorse sequence and some variants
(EDP Sciences, 2006)We consider the position and number of occurrences of squares in the ThueMorse sequence, and show that the corresponding sequences are 2regular. We also prove that changing any finite but nonzero number of bits in the ... 
Avelines's Hole: An Unexpected Twist in the Tale
(University of Bristol Spelaeological Society, 2019)Aveline’s Hole is the largest known Early Mesolithic cemetery in Britain, previously thought to have no evidence for subsequent burial activity. Thus, it came as some surprise when the results of a recent ancient human DNA ... 
Supporting Teachers in Times of Change: The Job Demands Resources Model and Teacher Burnout During the COVID19 Pandemic
(RedFame, 202010)Burnout in teachers has been broadly investigated, but no studies have investigated burnout in teachers during a pandemic. The current study is based on a survey of 1278 Canadian teachers and examined whether the Job ... 
Extremal words in morphic subshifts
(Elsevier, 20140122)Given an infinite word x over an alphabet A, a letter b occurring in x, and a total order \sigma on A, we call the smallest word with respect to \sigma starting with b in the shift orbit closure of x an extremal word of ... 
Unary patterns under permutations
(Elsevier, 20180604)Thue characterized completely the avoidability of unary patterns. Adding function variables gives a general setting capturing avoidance of powers, avoidance of patterns with palindromes, avoidance of powers under coding, ... 
Avoiding three consecutive blocks of the same size and same sum
(Association of Computing Machinery, 201404)We show that there exists an inﬁnite word over the alphabet {0,1,3,4} containing no three consecutive blocks of the same size and the same sum. This answers an open problem of Pirillo and Varricchio from1994. 
Growth rate of binary words avoiding xxxR
(Elsevier, 201601)Abstract Consider the set of those binary words with no nonempty factors of the form xxx^R. Du, Mousavi, Schaeffer, and Shallit asked whether this set of words grows polynomially or exponentially with length. In this ... 
Abelian complexity of fixed point of morphism 0 > 012, 1 > 02, 2 > 1
(20160214)We study the combinatorics of vtm, a variant of the ThueMorse word generated by the nonuniform morphism 0 > 012,1 > 02,2 > 1 starting with 0. This inﬁnite ternary sequence appears a lot in the literature and ﬁnds ... 
Binary Words Avoiding xxRx and Strongly Unimodal Sequences
(20150914)In previous work, Currie and Rampersad showed that the growth of the number of binary words avoiding the pattern xxxR was intermediate between polynomial and exponential. We now show that the same result holds for the ... 
A family of formulas with reversal of high avoidability index
(World Scientific, 2017)We present an infinite family of formulas with reversal whose avoidability index is bounded between 4 and 5, and we show that several members of the family have avoidability index 5. This family is particularly interesting ... 
Avoidability index for binary patterns with reversal
(2017)For every pattern p over the alphabet {x,x^R,y,y^R}, we specify the least k such that p is kavoidable. 
Attainable lengths for circular binary words avoiding kpowers
(The Belgian Mathematical Society, 2005)We show that binary circular words of length n avoiding 7/3+ powers exist for every sufficiently large n. This is not the case for binary circular words avoiding k+ powers with k < 7/3 
The Number of Ternary Words Avoiding Abelian Cubes Grows Exponentially
(20040619)We show that the number of ternary words of length n avoiding abelian cubes grows faster than r^n, where r = 2^{1/24} 
The metric dimension and metric independence of a graph
(The Charles Babbage Research Centre, 2001)A vertex x of a graph G resolves two vertices u and v of G if the distance from x to u does not equal the distance from x to v. A set S of vertices of G is a resolving set for G if every two distinct vertices of G are ...