关键词: 物元可拓, 改进, 水质评价

Abstract:  It is defined in the extension monograph that “the extension concourse uses real numbers ranging in (-∞, ∞) to denote the character degree of some  things. Positive number denotes the degree of the character that things have, while the negative ones denotes the character degree that things do not have, and zero denotes the character that things have as well as have not". The “+" and “-" symbols are used for qualitative objective. The “+" and “-" symbols are used for quantification for the matterelement extension method, which  take the maximum degree of relationship as the rule of assessment.. The improvement of  this matter-element extension method is put forth, of which the essential is to improve the relationship degree and the rule of assessment. In addition, the improved method is applied to the water quality assessment of Yellow River with more rational results.

Key words: matter-element extension, improvement, water quality assessment