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2. The class of neat reducts is not elementary. Electronically available at http://www.renyi.hu/pub/algebraic-logic/neatelem.html.
3. On a stronger version of the finitization problem. Presented in Conference in Algebra (in honour of the 70th birthday of Ervin Fried), August 17 - 21 1999, Alfred Rényi Institute of Mathematics, Budapest, Hungary. Electronically available at http://www.renyi.hu/∼rabbit/.
4. A Modeltheoretic Solution to a Problem of Tarski