设D为n维Euclid空间R^n的一个有界区域,且0〈λ1〈λ2≤λ3≤…≤λk≤…,是 l阶Laplace算子的Dirichlet问题 {(-△)^lu=λu,在D中, u=δu/δn=…=δ^l-1u/δn^1-1=0,在δD上 } 的特征值,其中l是正整数,n表示边界δD的外法向量.该文得到了该问题用其前k个特征值来估计第(k+1)个特征值λk+1的不等式∑ i=1(λk+1-λi)[λk+1-(1+4l/n+2l-2)λi]∫D|△↓^l-1ui|^2≤0.此不等式不依赖于区域D.ui是相应于特征根λi的特征函数.当l=1时得到了杨洪苍的不等式,所以上述不等式是杨洪苍不等式的一个推广.
Let D be a connected bounded domain in an n-dimentional Euclidean space R^n. Assume that 0 〈 λ1 〈 λ2 ≤λ3 ≤... ≤λk ≤... , are eigenvalues of Laplacian operator with any order 1 for the Dirichlet problem: {(-△)^lu=λu,in D; u=δu/δn=…=δ^l-1u/δn^1-1=0,onδD, } where l ∈ N^+, n is the unit outward normal to δD. Then we obtain an upper bound of the (k + 1) - th eigenvalue λk+l in terms of the first k eigenvalues. This inequality k is independent of domain D, that is, we prove the following: ∑ i=1(λk+1-λi)[λk+1-(1+4l/n+2l-2)λi]∫D|△↓^l-1ui|^2≤0 . ui is the corresponding eigenfunction with eigenvalue λi. When l is 1, we recover Yang Hongcang's inequality.