136 research outputs found

    Biordered sets come from semigroups

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    Student Perspectives on Summer School Versus Term-Time for Undergraduate Mathematics

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    Earlier studies at The University of Sydney indicate that students undertaking certain first year mathematics units in intensive mode of delivery (IMD) achieved superior learning outcomes compared to those completing the same units during the semester. The aim of this study is to survey students that took any undergraduate mathematics units offered in IMD over the period 2009-2016, asking them to compare summer school with semester learning environments. While data suggest that the learning environment is overwhelmingly in favour of summer school, there are features of both modes that appear to be successful. This leads to a flow-diagram, akin to Biggs’ Presage-Process-Product (3P) model, emphasising presage and temporality

    The minimal faithful permutation degree for a direct product obeying an inequality condition

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    The minimal faithful permutation degree μ(G)\mu(G) of a finite group GG is the least nonnegative integer nn such that GG embeds in the symmetric group \Sym(n). Clearly μ(G×H)μ(G)+μ(H)\mu(G \times H) \le \mu(G) + \mu(H) for all finite groups GG and HH. Wright (1975) proves that equality occurs when GG and HH are nilpotent and exhibits an example of strict inequality where G×HG\times H embeds in \Sym(15). Saunders (2010) produces an infinite family of examples of permutation groups GG and HH where μ(G×H)<μ(G)+μ(H)\mu(G \times H) < \mu(G) + \mu(H), including the example of Wright's as a special case. The smallest groups in Saunders' class embed in \Sym(10). In this paper we prove that 10 is minimal in the sense that μ(G×H)=μ(G)+μ(H)\mu(G \times H) = \mu(G) + \mu(H) for all groups GG and HH such that μ(G×H)9\mu(G\times H)\le 9.Comment: 22 page

    How to identify and control mung bean pest

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    Braids and factorizable inverse monoids

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    What is the untangling effect on a braid if one is allowed to snip a string, or if two specified strings are allowed to pass through each other, or even allowed to merge and part as newly reconstituted strings? To calculate the effects, one works in an appropriate factorizable inverse monoid, some aspects of a general theory of which are discussed in this paper. The coset monoid of a group arises, and turns out to have a universal property within a certain class of factorizable inverse monoids. This theory is dual to the classical construction of fundamental inverse semigroups from semilattices. In our braid examples, we will focus mainly on the ``merge and part'' alternative, and introduce a monoid which is a natural preimage of the largest factorizable inverse submonoid of the dual symmetric inverse monoid on a finite set, and prove that it embeds in the coset monoid of the braid group

    The importance of true-false statements in mathematics teaching and learning

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    The author suggests that true-false statements are a valuable tool in mathematical pedagogy, in moving students through the passive/active interface and nudging or directing them towards mathematical ideas of historical and contemporary importance

    Periodic elements of the free idempotent generated semigroup on a biordered set

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    We show that every periodic element of the free idempotent generated semigroup on an arbitrary biordered set belongs to a subgroup of the semigroup

    Presentations of factorizable inverse monoids

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    It is well-known that an inverse monoid is factorizable if and only if it is a homomorphic image of a semidirect product of a semilattice (with identity) by a group. We use this structure to describe a presentation of an arbitrary factorizable inverse monoid in terms of presentations of its group of units and semilattice of idempotents, together with some other data. We apply this theory to quickly deduce a well known presentation of the symmetric inverse monoid on a nite set
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