Three-dimensional numerical calculations of Heliac equilibria are presented. The results indicate that finite-/3 distortions in the flux surfaces can arise because of the presence of low order rational surfaces within or near the plasma. These distortions arise as a result of non-linear beatings between the toroidal shift and the helical components of the magnetic field. Reducing the toroidal shift by increasing the number of field periods and/or the aspect ratio improves the equilibrium |3-limit.

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In this article hyperidentities of the variety of Boolean algebras are characterized. A corollary of this characterization is the determination of a finite basis of hyperidentities for this variety. However, the class of polynomial algebras of Boolean algebras does not have a finite basis of hyperidentities. §o A hyperidentity (or V(V)-identity) is a formula in a second-order language (see [1] and [2]

Available online xxxx Keywords: Antichain De Morgan function Monotone Boolean function Disjunctive (conjunctive) normal form of De Morgan function Closed class Complete and precomplete classes Quasimonotone and zigzag De Morgan functions a b s t r a c tIn this paper we define disjunctive and conjunctive normal forms of De Morgan functions and prove a functional completeness theorem for these functions.

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