Samuel A. Alexander

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Current strategies for management of Pratylenchus penetrans in both white potato and tomato consist of the use of fumigant or non-fumigant nematicides or crop rotation. The objective of this study was to determine if double-cropping African marigolds (Tagetes erecta) with potatoes or tomatoes could reduce P. penetrans populations. Plots were 10 m x 3 m(More)
We argue that C. Darwin and more recently W. Hennig worked at times under the simplifying assumption of an eternal biosphere. So motivated, we explicitly consider the consequences which follow mathematically from this assumption, and the infinite graphs it leads to. This assumption admits certain clusters of organisms which have some ideal theoretical(More)
Reinhardt’s conjecture, a formalization of the statement that a truthful knowing machine can know its own truthfulness and mechanicalness, was proved by Carlson using sophisticated structural results about the ordinals and transfinite induction just beyond the first epsilon number. We prove a weaker version of the conjecture, by elementary methods and(More)
Nested clusters arise independently in graph partitioning and in the study of contours. We take a step toward unifying these two instances of nested clusters. We show that the graph theoretical tight clusters introduced by Dress, Steel, Moulton and Wu in 2010 are a special case of nested clusters associated to contours.
A biologically unavoidable sequence is an infinite gender sequence which occurs in every gendered, infinite genealogical network satisfying certain tame conditions. We show that every eventually periodic sequence is biologically unavoidable (this generalizes König’s Lemma), and we exhibit some biologically avoidable sequences. Finally we give an application(More)
Power Electronics is defined as electronic circuits used for electrical conversion. The conversion includes rectification and inversion. For a UPS inverter the output voltage obtained for the linear load is sinusoidal whereas for the non linear loading conditions the output voltage waveform is highly distorted. Hence it is necessary to maintain a sinusoidal(More)
Internodons are a formalization of Hennig's concept of species. We present an alternative construction of internodons imposing a tree structure on the genealogical network. We prove that the segments (trivial unary trees) from this tree structure are precisely the internodons. We obtain the following spin-offs. First, the generated tree turns out to be an(More)
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