1,724,811 research outputs found
Income Distribution and Poverty in a CGE Framework: A Proposed Methodology
Get PDFThe paper discusses methodologies addressing income distribution and poverty in a Computable General Equilibrium (CGE) model framework, by describing how to link CGE results with household survey data to analyze income distribution and poverty implications. The most basic approach is simply to fit the household income/expenditure to the survey data by suitable parametric distribution functions. The post-simulation poverty indices can be estimated by either assuming that the income of each individual household within the group moves proportionally with the group's mean income, or by our proposed elasticity method. In our proposed method, we use the elasticity estimated from existing surveys to calculate the change in expenditure of each subgroup category in response to change in the household category's mean consumption, supplied by the core model's simulation, to derive post-simulation poverty indices. Our approach may better capture intra-group income distribution of households and moderate gains or losses in welfare from economic growths.Computable General Equilibrium, Income Distribution, Poverty.
Finding branch-decompositions and rank-decompositions
No full textAccepted to SIAM J. Comput., 2008.We present a new algorithm that can output the rank-decomposition of width at most k of a graph if such exists. For that we use an algorithm that, for an input matroid represented over a fixed finite field, outputs its branch-decomposition of width at most k if such exists. This algorithm works also for partitioned matroids. Both of these algorithms are fixed-parameter tractable, that is, they run in time O(n(3)) where n is the number of vertices / elements of the input, for each constant value of k and any fixed finite field. The previous best algorithm for construction of a branch-decomposition or a rank-decomposition of optimal width due to Oum and Seymour [J. Combin. Theory Ser. B, 97 (2007), pp. 385 - 393] is not fixed-parameter tractable.The first author: Supported by Czech research grant GAČR 201/08/0308 and by Research intent MSM0021622419 of the
Czech Ministry of Education.
The second author:
This research was done while the second author was at Georgia Institute of Technology and
University of Waterloo. Partially supported by NSF grant DMS 0354742 and the SRC Program
of Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea government
(MOST) (No. R11-2007-035-01002-0)
IPD-OUM Certificate Presentation Ceremony
Get PDFSpeech of the President/Vice-Chancellor OUM, Prof Tan Sri Anuwar Ali on collaborative programme with Jaya Jusco at PWTC. 12 December 2003
Approximating Rank-Width and Clique-Width Quickly
No full textRank-width was defined by Oum and Seymour [ 2006] to investigate clique-width. They constructed an algorithm that either outputs a rank-decomposition of width at most f(k) for some function f or confirms that rank-width is larger than k in time O(vertical bar V vertical bar(9) log vertical bar V vertical bar) for an input graph G = (V, E) and a fixed k. We develop three separate algorithms of this kind with faster running time. We construct an O(vertical bar V vertical bar(4))-time algorithm with f(k) = 3k + 1 by constructing a subroutine for the previous algorithm; we avoid generic algorithms minimizing submodular functions used by Oum and Seymour. Another one is an O(vertical bar V vertical bar(3))-time algorithm with f(k) = 24k, achieved by giving a reduction from graphs to binary matroids; then we use an approximation algorithm for matroid branch-width by Hlineny [2005]. Finally we construct an O(vertical bar V vertical bar(3))-time algorithm with f(k) = 3k - 1 by combining the ideas of the two previously cited papers
Rank-width and well-quasi-ordering
No full textRobertson and Seymour [J. Combin. Theory Ser. B, 48 (1990), pp. 227-254] proved that graphs of bounded tree-width are well-quasi-ordered by the graph minor relation. By extending their arguments, Geelen, Gerards, and Whittle [J. Combin. Theory Ser. B, 84 (2002), pp. 270-290] proved that binary matroids of bounded branch-width are well-quasi-ordered by the matroid minor relation. We prove another theorem of this kind in terms of rank-width and vertex-minors. For a graph G = (V, E) and a vertex v of G, a local complementation at v is an operation that replaces the subgraph induced by the neighbors of v with its complement graph. A graph H is called a vertex-minor of G if H can be obtained from G by applying a sequence of vertex deletions and local complementations. Rank-width was defined by Oum and Seymour [J. Combin. Theory Ser. B, 96 (2006), pp. 514-528] to investigate clique-width; they showed that graphs have bounded rank-width if and only if they have bounded clique-width. We prove that graphs of bounded rank-width are well-quasi-ordered by the vertex-minor relation; in other words, for every infinite sequence G(1), G(2),... of graphs of rank-width (or clique-width) at most k, there exist i < j such that G(i) is isomorphic to a vertex-minor of G(j). This implies that there is a finite list of graphs such that a graph has rank-width at most k if and only if it contains no one in the list as a vertex-minor. The proof uses the notion of isotropic systems defined by Bouchet.This work was performed while the author was at the Pro-
gram in Applied and Computational Mathematics, Princeton University, Princeton,
New Jersey and partially supported by the SRC program of Korea Science and Engi-
neering Foundation grant funded by Korea government (MOST)(No. R11-2007-035-
01002-0)
Conference address by YBhg President/Vice-Chancellor OUM, Prof Tan Sri Anuwar Ali at National Institute of Accountants Conference
No full textSpeech of the President/Vice-Chancellor OUM, Prof Tan Sri Anuwar Ali at National Institute of Accountants Conference
International Collaborations in Higher Education - A Case Study of OUM Business School and HUTECH, Vietnam
No full textGovernments all over the world generally recognise the important role that higher education
(HE) plays in meeting the challenges borne by globalisation. Australia, Europe, Singapore,
Malaysia, Saudi Arabia and Dubai have all recognised the importance of internationalisation of
HE and universities are turning towards franchising due to increased financial pressure, higher
autonomy and an increasingly competitive market. As part of its efforts to widen access to
education, OUM has ventured overseas and is currently working with many overseas partners
and collaborators. This research focuses on the OUM Business School (OUMBS) which
currently offers its programmes overseas through various collaborative partners. The case in
hand focuses on the international collaborative partnership between OUMBS and Ho Chi Minh
University of Technology (HUTECH) and discusses the current experiences faced by the two
partners. Findings from the case highlight the advantages and disadvantages of a collaborative
partnership plus the lessons that could be learnt. (Abstract by authors
Finding branch-decompositions of matroids, hypergraphs, and more
Get PDFGiven subspaces of a finite-dimensional vector space over a fixed finite
field , we wish to find a "branch-decomposition" of these subspaces
of width at most that is a subcubic tree with leaves mapped
bijectively to the subspaces such that for every edge of , the sum of
subspaces associated to the leaves in one component of and the sum of
subspaces associated to the leaves in the other component have the intersection
of dimension at most . This problem includes the problems of computing
branch-width of -represented matroids, rank-width of graphs,
branch-width of hypergraphs, and carving-width of graphs.
We present a fixed-parameter algorithm to construct such a
branch-decomposition of width at most , if it exists, for input subspaces of
a finite-dimensional vector space over . Our algorithm is analogous
to the algorithm of Bodlaender and Kloks (1996) on tree-width of graphs. To
extend their framework to branch-decompositions of vector spaces, we developed
highly generic tools for branch-decompositions on vector spaces. The only known
previous fixed-parameter algorithm for branch-width of -represented
matroids was due to Hlin\v{e}n\'y and Oum (2008) that runs in time
where is the number of elements of the input -represented
matroid. But their method is highly indirect. Their algorithm uses the
nontrivial fact by Geelen et al. (2003) that the number of forbidden minors is
finite and uses the algorithm of Hlin\v{e}n\'y (2006) on checking monadic
second-order formulas on -represented matroids of small
branch-width. Our result does not depend on such a fact and is completely
self-contained, and yet matches their asymptotic running time for each fixed
.Comment: 79 pages, 15 figures; Fix a few English issues. To appear in SIAM J.
Discrete Mat
Obstructions for bounded branch-depth in matroids
No full textDeVos, Kwon, and Oum introduced the concept of branch-depth of matroids as a
natural analogue of tree-depth of graphs. They conjectured that a matroid of
sufficiently large branch-depth contains the uniform matroid or the
cycle matroid of a large fan graph as a minor. We prove that matroids with
sufficiently large branch-depth either contain the cycle matroid of a large fan
graph as a minor or have large branch-width. As a corollary, we prove their
conjecture for matroids representable over a fixed finite field and
quasi-graphic matroids, where the uniform matroid is not an option
Rank connectivity and pivot-minors of graphs
Get PDFThe cut-rank of a set in a graph is the rank of the submatrix of the adjacency matrix over the binary field. A split is a
partition of the vertex set into two sets such that the cut-rank of
is less than and both and have at least two vertices. A graph is
prime (with respect to the split decomposition) if it is connected and has no
splits. A graph is -rank-connected if for every set of
vertices with the cut-rank less than , or is less than . We prove that every prime
-rank-connected graph with at least vertices has a prime
-rank-connected pivot-minor such that . As a corollary, we show that every excluded pivot-minor for the
class of graphs of rank-width at most has at most
vertices for . We also show that the excluded pivot-minors for the
class of graphs of rank-width at most have at most vertices.Comment: 23 pages, 1 figure. Accepted to the European Journal of Combinatoric
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