| Abstract: |
| We study the spectrum of a $(p, q)$-biharmonic system on a bounded domain. Under appropriate conditions, we prove that the system either has at least one nondecreasing sequence of positive eigenvalues, or has at least one noninceasing sequence of negative eigenvalues or has both at least one nondecreasing sequence of positive eigenvalues and at least one nonincreasing sequence of negative eigenvalues. Our results apply respectively to the cases when the weight functions in the system are positive definite, negative definite, or indefinite. |
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