Spring 2012 Seminars
Time: Monday, 30 April 2012, 3:10 PM Place: SC 1310 Speaker: Matthew Smedberg Title: Type 2 and 3 covers in finitely decidable varieties have empty tails One of the central themes in classifying varieties V which 

Time: Friday, 13 April 2012, 3:10 PM Place: SC 1310 Speaker: William Young Title: Algebras Induced by a Unary Term This talk will introduce the concept of an algebra induced by a unary term. If A is an algebra in the variety V and \tau is a unary term in the language of V, the induced algebra A_{\tau} is the image of A under \tau, together with the induced operations defined by taking \tau of the original operations. It will be shown that this map is in fact a functor \Lambda from V to W, the class of subalgebras of the induced algebras.The main result of the talk is that the free algebra in W is a subalgebra of \Lamdba of the free algebra in V. After proving this, we will go through two specific examples of the construction to illustrate its usefulness. 

Time: Friday, 23 March 2012, 3:10 PM Place: SC 1310 Speaker: Alexander Wires Title: NearUnanimity for Reflexive Digraphs II We will continue the proof of the following recent result of M. Maroti and L. Zadori: A finite reflexive digraph admits Gumm operations iff it admits a nearunanimity operation. 

Time: Wednesday, 21 March 2012, 4:10 PM Place: SC 1310 Speaker: Chris Conidis Title: Proving that Artinian implies Noetherian without proving that Artinian implies finite length Joint Meeting with Group Theory and Topology Seminar Let R be a commutative ring with identity. Recall from basic graduate algebra that: 1. R is Noetherian if it satisfies the ascending chain condition on its ideals; It is wellknown that 2. implies 1., but the proofs given in most standard algebra texts prove this by showing the stronger statement that 2. implies 3. This begs the question: “Can one prove that 2. implies 1. without showing that 2. implies 3? We will show that this is indeed the case by showing that, in the context of reverse mathematics, the former (weaker) statement is equivalent to weak Konig’s lemma, while the latter (stronger) statement is equivalent to arithmetic comprehension in the context of $omega$models. Another way to view our main result is that it constructs an $\omega$model of RCA (recursive comprehension axiom) in which 2. implies 1., but 2. does not imply 3. 

Time: Friday, 16 March 2012, 3:10 PM Place: SC 1310 Speaker: Alexander Wires Title: NearUnanimity for Reflexive Digraphs I We will study and prove the following recent result of M. Maroti and L. Zadori: A finite reflexive digraph admits Gumm operations iff it admits a nearunanimity operation. The result is important for the algebraic study of Constraint Satisfaction Problems and for the recently studied phenomenon of Malcev collapse for finitely related algebras. 

Time: Friday, 3 February 2012, 3:10 PM Place: SC 1310 Speaker: Simone Bova Title: Post Lattice in the Complexity Classification of Satisfiability Problems 

Time: Friday, 20 January 2012, 3:10 PM Place: SC 1310 Speaker: George Metcalfe Title: Interpolation and amalgamation in Sugihara monoids Sugihara monoids (idempotent involutive semilinear commutative residuated 
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