The crystallographic problems of two-dimensional crystal,such as the matrix expression, the symmetry and the systematic absence law of the crystal's X-ray diffraction, are studied.

In this paper propose the representation of classification′s matrix expression;the attribute reduction based on matrix expression,and give some examples to explain our algorithm is efficient.

The axiomatic system in Pawlak rough approximation space is studied by use of matrix expression of fuzzy relation and its operation.

Based on the minimizing the distance function between two Bézier curves in the sense of the least squares normal(L 2), a method for approximate merging of two adjacent degree n Bézier curves by a single degree n Bézier curve is given by using matrix representation of Bézier curve subdivision.

In this paper, the matrix representation of a partial order is defined.

Then the matrix representation of the continuum equation of probability density is presented by virtue of the probability density matrix,the differential operator matrix and the matrix of probability current density vector configured in the coordinate representation,and some discussions are given.