111 research outputs found
Hedge Hog! by A. Anstee
No full textAnstee, Ashlyn. Hedge Hog! Illustrated by Ashlyn Anstee. Tundra Books, 2018.After Are We There, Yeti? and No, No, Gnome!, Canadian born author/illustrator/animator Ashlyn Anstee presents us with the delightfully punny Hedge Hog!. In this story, our titular main character Hedgehog tries to keep all the other yard animals away from his hedge. Can the other animals convince him to open up his doors before winter comes? Not if Hedgehog has anything to say about it. The author tells a simple, yet charming story that can be used to teach a young reader about the importance of sharing and caring for your neighbours or as a political allegory dealing with immigration. Some readers will also enjoy the tale for what it is, a fun and entertaining story. The art is the real strong point of this story. The charming and pleasant looking characters, and the world of the yard that the author creates are sure to appeal to anyone reading through this book. Just the cover art alone is likely to pique anyone's interest. The illustrations are not only cute, but they also do a wonderful job of conveying the story. Regardless of the reader's reading level, they are sure to get something out of this tale.With strong, yet easily digestible writing and charming illustrations, this story is perfect for new readers. Whether they are reading by themselves or along with their parents, there is lots to fall in love with here.Highly Recommended: 4 out of 4 starsReviewer: Adam CohenAdam has his BSc in archaeology from the University of Calgary and is a current graduate student in the University of Alberta’s Masters of Library and Information Studies program. He is also a member of Future Librarians for Intellectual Freedom, and works as a metadata assistant at the University of Alberta Libraries. </jats:p
Matrices with forbidden subconfigurations
No full textAbstractWe consider matrices with entries from the set {0, 1, …, q−1}. Suppose that Sk is a k×qk matrix having all possible k-tuples as columns. We determine the best possible bound f(m, k) with the property that if A is any m×(f(m, k)+1) matrix of distinct columns, then some row and column permutation of A contains Sk as a submatrix. Our result generalizes a number of the results for q = 2 due to Anstee, Füredi, Quinn, Sauer, Perles and Shelah, and is obtained by means of a simple inductive argument. Interesting matrices meeting the bound are constructed
Properties of (0, 1)-matrices without certain configurations
No full textAbstractWe generalize results of Ryser on (0, 1)-matrices without triangles, 3 × 3 submatrices with row and column sums 2. The extremal case of matrices without triangles was previously studied by the author. Let the row intersection of row i and row j (i ≠ j) of some matrix, when regarded as a vector, have a 1 in a given column if both row i and row j do not 0 otherwise. For matrices satisfying some conditions on forbidden configurations and column sums ⩾ 2, we find that the number of linearly independent row intersections is equal to the number of distinct columns. The extremal matrices with m rows and (m2) distinct columns have a unique SDR of pairs of rows with 1's. A triangle bordered with a column of 0's and its (0, 1)-complement are also considered as forbidden configurations. Similar results are obtained and the extremal matrices are closely related to the extremal matrices without triangles
Pairwise intersections and forbidden configurations
Get PDFLet fm(a, b, c, d) denote the maximum size of a family F of subsets of an m-element set for which there is no pair of subsets A, B ∈ F with |A ∩ B | ≥a, |Ā ∩ B | ≥b, |A ∩ ¯B | ≥c, and |Ā ∩ ¯B | ≥d. By symmetry we can assume a ≥ d and b ≥ c. We show that fm(a, b, c, d) is Θ(m a+b−1) if either b> c or a, b ≥ 1. We also show that fm(0, b, b, 0) is Θ(m b) and fm(a, 0, 0, d) is Θ(m a). The asymptotic results are as m →∞for fixed non-negative integers a, b, c, d. This can be viewed as a result concerning forbidden configurations and is further evidence for a conjecture of Anstee and Sali. Our key tool is a strong stability version of the Complete Intersection Theorem of Ahlswede and Khachatrian, which is of independent interest
LARGE FORBIDDEN CONFIGURATIONS AND DESIGN THEORY
Get PDFLet forb(m, F) denote the maximum number of columns possible in a (0, 1)-matrix A that has no repeated columns and has no submatrix which is a row and column permutation of F. We consider cases where the configuration F has a number of columns that grows with m. For a k x l matrix G, define s . G to be the concatenation of s copies of G. In a number of cases we determine forb(m, m(alpha).G) is Theta(m(k+alpha)). Results of Keevash on the existence of designs provide constructions that can be used to give asymptotic lower bounds. An induction idea of Anstee and Lu is useful in obtaining upper bounds
Forbidden configurations and repeated induction
No full textAbstractFor a given k×ℓ matrix F, we say a matrix A has no configuration F if no k×ℓ submatrix of A is a row and column permutation of F. We say a matrix is simple if it is a (0,1)-matrix with no repeated columns. We define forb(m,F) as the maximum number of columns in an m-rowed simple matrix which has no configuration F. A fundamental result of Sauer, Perles and Shelah, and Vapnik and Chervonenkis determines forb(m,Kk) exactly, where Kk denotes the k×2k simple matrix. We extend this in several ways. For two matrices G,H on the same number of rows, let [G∣H] denote the concatenation of G and H. Our first two sets of results are exact bounds that find some matrices B,C where forb(m,[Kk∣B])=forb(m,Kk) and forb(m,[Kk∣Kk∣C])=forb(m,[Kk∣Kk]). Our final result provides asymptotic boundary cases; namely matrices F for which forb(m,F) is O(mp) yet for any choice of column α not in F, we have forb(m,[F∣α]) is Ω(mp+1). This is evidence for a conjecture of Anstee and Sali. The proof techniques in this paper are dominated by repeated use of the standard induction employed in forbidden configurations. Analysis of base cases tends to dominate the arguments. For a k-rowed (0,1)-matrix F, we also consider a function req(m,F) which is the minimum number of columns in an m-rowed simple matrix for which each k-set of rows contains F as a configuration
Multivalued matrices and forbidden configurations
No full textAn r-matrix is a matrix with symbols in {0, 1, . . . , r − 1}. A matrix is simple if
it has no repeated columns. Let F be a finite set of r-matrices. Let forb(m, r, F)
denote the maximum number of columns possible in a simple r-matrix A that
has no submatrix which is a row and column permutation of any F ∈ F. Many
investigations have involved r = 2. For general r, forb(m, r, F) is polynomial in
m if and only if for every pair i, j ∈ {0, 1, . . . , r − 1} there is a matrix in F whose
entries are only i or j. Let T l (r) denote the following r-matrices. For a pair
i, j ∈ {0, 1, . . . , r − 1} we form four l × l matrices namely the matrix with i’s on
the diagonal and j’s off the diagonal and the matrix with i’s on and above the
diagonal and j’s below the diagonal and the two matrices with the roles of i, j
reversed. Anstee and Lu determined that forb(m, r, T l (r)) is a constant. Let F be
a finite set of 2-matrices. We ask if forb(m, r, T l (3)\T l (2) ∪ F) is Θ(forb(m, 2, F))
and settle this in the affirmative for some cases including most 2-columned F
Evidence for a forbidden configuration conjecture: One more case solved
No full textAbstractA simple matrix is a (0,1)-matrix with no repeated columns. Let F and A be (0,1)-matrices. We say that A avoids F if there is no submatrix of A which is a row and column permutation of F. Let ‖A‖ denote the number of columns of A. We define forb(m,F)=max{‖A‖:A is an m-rowed simple matrix which avoids F}.For two matrices H and K, define [H∣K] as the concatenation of H and K. Let t⋅H denote the concatenation of t copies of H. Given a number t with t≥1, define F8(t)=[1010010111001100t⋅[10011100]].We are able to show that forb(m,F8(t)) is Θ(m2) and that this matrix is “maximal” (in some sense) with respect to this property. A conjecture of Anstee and Sali predicts three “maximal” 4-rowed cases to consider with quadratic bounds, and F8(t) is one of them. Establishing the quadratic upper bounds for all three cases would establish the veracity of the conjecture for all 4-rowed configurations
Properties of (0, 1)-matrices with no triangles
No full textAbstractWe study (0, 1)-matrices which contain no triangles (submatrices of order 3 with row and column sums 2) previously studied by Ryser. Let the row intersection of row i and row j of some matrix, when regarded as a vector, have a 1 in a given column if both row i and row j do and a zero otherwise. For matrices with no triangles, columns sums ⩾2, we find that the number of linearly independent row intersections is equal to the number of distinct columns. We then study the extremal (0, 1)-matrices with no triangles, column sums ⩾2, distinct columns, i.e., those of size mx(m2). The number of columns of column sum l is m − l + 1 and they form a (l − 1)-tree. The ((m2)) columns have a unique SDR of pairs of rows with 1's. Also, these matrices have a fascinating inductive buildup. We finish with an algorithm for constructing these matrices
Aquatic Substrate Library - Wallis Lake 2001
No full textMaintenance and Update Frequency: asNeededStatement: This dataset is part of the NSD Aquatic Spectral Library<b>Purpose</b><br/>Application of spectral data to plant physiology studies, geological sciences, soil sciences, limnology, oceanography and atmospheric chemistry, and other research.Record for source data hosted in the National Spectral Database (NSD) Aquatic Library<br/><br/>Citation:<br/>Dekker, A. G., Anstee, J. M., and Brando, V. E. (2002) Seagrass change assessment using satellite data for Wallis lake. Canberra, ACT, Australia, CSIRO Land & Water. Technical Report 13/04<br/>Publication:<br/>Dekker, A. G., Anstee, J. M., and Brando, V. E. (2005) Retrospective seagrass change detection in a shallow coastal tidal Australian lake, Rem. Sens. Environm. Vol. 97 (4), pp. 415-433. https://doi.org/10.1016/j.rse.2005.02.017<br/><br/>For further information and instructions to access the database go to the following URL:<br/>https://cmi.ga.gov.au/data-products/dea/643/australian-national-spectral-databas
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