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Knowledge Reduction in Crisply Generated Fuzzy Concept Lattices

100%

Li M.-Z. , Wang G.-Y.

tom Vol. 142, nr 1-4

307--335

Knowledge reduction is a basic issue in knowledge representation and data mining. Although various methods have been developed to reduce the size of classical formal contexts, the reduction of formal fuzzy contexts based on fuzzy lattices remains a difficult problem owing to its complicated derivation operators. To address this problem, this paper proposes a method of knowledge reduction by reducing attributes in a formal fuzzy context based on the crisply generated fuzzy concept lattice. Employing the proposed approach, attributes which are non-essential to the structure of the crisply generated fuzzy concept lattice are removed. Discernibility matrix and Boolean function are employed to compute the attribute reducts of the formal fuzzy contexts, by which all the attribute reducts of the formal fuzzy contexts are determined without changing the structure of the lattice. Further, all the attributes are classified into three types by their significance in constructing the crisply generated fuzzy concept lattice. The characteristics of these types of attributes are also analyzed. Finally, the proposed method is used to conduct knowledge reduction in the variable threshold concept lattices, which is a complement to the existing knowledge reduction methods.

Osmotic solute responses of mycorrhizal citrus (Poncirus trifoliata) seedlings to drought stress

80%

Wu Q.-S. , Xia R.-X. , Zou Y.-N. , Wang G.-Y.

tom 29

nr 6

This study investigated the accumulation of osmotic solutes in citrus (Poncirus trifoliata) seedlings colonized by Glomus versiforme subjected to drought stress or kept well watered. Development of mycorrhizae was higher under well watered than under drought-stressed conditions. Arbuscular mycorrhizal (AM) seedlings accumulated more soluble sugars, soluble starch and total non-structural carbohydrates in leaves and roots than corresponding non-AM seedlings regardless of soil-water status. Glucose and sucrose contents of well-watered and drought-stressed roots, fructose contents of well-watered roots and sucrose contents of drought-stressed leaves were notably higher in AM than in non-AM seedlings. K⁺ and Ca²⁺ levels in AM leaves and roots were greater than those in non-AM leaves and roots, while AM symbiosis did not affect the Mg²⁺ level. AM seedlings accumulated less proline than non-AM seedlings. AM symbiosis altered both the allocation of carbohydrate to roots and the net osmotic solute accumulations in response to drought stress. It is concluded that AM colonization enhances osmotic solute accumulation of trifoliate orange seedlings, thus providing better osmotic adjustment in AM seedlings, which did not correlate with proline but with K⁺, Ca²⁺, Mg²⁺, glucose, fructose and sucrose accumulation.