A Banach space operator T ∈ B(χ) is polaroid if points λ ∈ iso σ(T) are poles of the resolvent of T. Let sa(T), sw(T), saw(T), sSF+(T) and sSF-(T)sigma_a(T), sigma_w(T), sigma_{aw}(T), sigma_{SF_+}(T), rm{and},sigma_{SF_-}(T) denote, respectively, the approximate point, the Weyl, the Weyl essential approximate, the upper semi–Fredholm and lower semi–Fredholm spectrum of T. For A, B and C ∈ B(χ), let M C denote the operator matrix $left( {{ll} A & C 0 & B } right)$left( {begin{array}{ll} A & C 0 & B end{array} } right). If A is polaroid on p0(MC) = {l Î iso s(MC) : 0 < dim (MC - l)-1(0) < ¥}pi_{0}(M_{C}) = {{lambda in {rm iso}, sigma(M_{C}) : 0 < {rm dim} (M_{C} - lambda)^{-1}(0) < infty}}, M 0 satisfies Weyl’s theorem, and A and B satisfy either of the hypotheses (i) A has SVEP at points l Î sw(M0) sSF++(A)lambda in sigma_{w}(M_{0}) backslash {sigma_{SF_{+}}}+(A) and B has SVEP at points m Î sw(M0) sSF-(B)mu in sigma_{w}(M_{0}) backslash {sigma_{SF_{-}}}(B), or, (ii) both A and A* have SVEP at points l Î sw(M0) sSF+(A)lambda in sigma_{w}(M_{0}) backslash {sigma_{SF_{+}}}(A), or, (iii) A* has SVEP at points l Î sw(M0) sSF+(A)lambda in sigma_{w}(M_{0}) backslash {sigma_{SF_{+}}}(A) and B * has SVEP at points m Î sw(M0) sSF-(B)mu in sigma _{w}(M_{0}) backslash sigma_{SF_{-}}(B), then s(MC) sw(MC) = p0(MC)sigma (M_{C}) backslash sigma_{w}(M_{C}) = pi_{0}(M_{C}). Here the hypothesis that λ ∈ π0(M C ) are poles of the resolvent of A can not be replaced by the hypothesis l Î p0(A)lambda in pi_{0}(A) are poles of the resolvent of A. For an operator T Î B(c)T in B(chi), let p0a(T) = { l: l Î iso sa(T), 0 < dim (T - l)-1(0) < ¥}pi_{0}^{a}(T)= { lambda : lambda in,rm{iso}, sigma_a(T), 0 < , rm{dim},(T - lambda)^{-1}(0)< infty }. We prove that if A* and B* have SVEP, A is polaroid on π a 0(M C) and B is polaroid on π a 0(B), then sa (MC)saw(MC) = pa0(MC)sigma_a (M_C)backslash sigma_{aw}(M_C) = {pi^{a}_{0}}(M_C).
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机译:如果点λ∈isoσ(T)是T的解旋极,则Banach空间算子T∈B(χ)是宝丽来。令s a (T),s w (T),s aw (T),s SF + (T)和s SF -< / sub> (T)sigma_a(T),sigma_w(T),sigma_ {aw}(T),sigma_ {SF _ +}(T),rm {and},sigma_ {SF _-}(T)分别表示近似点,Weyl,Weyl本质近似,T的上半弗雷德霍姆谱和下半弗雷德霍姆谱。对于A,B和C∈B(χ),令M C 表示运算符矩阵$ left({{ll} A&C 0&B} right)$ left({begin {array} {ll} A&C 0&B end {array}} right)。如果A是p 0 (M C )上的宝丽来= {lÎiso s(M C ):0 <暗(M C -l) -1 (0)<¥} pi_ {0}(M_ {C})= {{lambda in {rm iso},sigma(M_ {C} ):0 <{rm dim}(M_ {C}-lambda)^ {-1}(0) 0 满足Weyl定理,并且A和B满足以下任一个假设(i)A在点l s w (M 0 )s SF + +( A)sigma_ {w}(M_ {0})中的反斜杠{sigma_ {SF _ {+}}} +(A)和B在点m s w (M 0 )s SF - (B)mu in sigma_ {w}(M_ {0})反斜杠{sigma_ {SF _ {-}}}((B ),或(ii)A和A *在点l s s w (M 0 )s SF + (A)sigma_ {w}(M_ {0})中的反斜杠{sigma_ {SF _ {+}}}(A),或者(iii)A * 具有SVEP在点σs w (M 0 )s SF + (A)sigma_ {w}中的λ (M_ {0})反斜杠{sigma_ {SF _ {+}}}(A)和B * 在点m s w (M 0 )s < sub> SF - (B)mu in sigma _ {w}(M_ {0})反斜杠sigma_ {SF _ {-}}(B),然后是s(M C )s w (M C )= p 0 (M C )sigma(M_ {C})反斜杠sigma_ {w}(M_ {C})= pi_ {0}(M_ {C})。在这里,λ∈π 0 (M C )是A的分解体的极点的假设不能由假设lÎp 0 (A)λ是A的旋转角。对于B(chi)中的算子TÎB(c)T,令p 0 a (T)= {l:l iso iso s a (T),0 <昏暗(T-l) -1 (0)<¥ } pi_ {0} ^ {a}(T)= {lambda:lambda in,rm {iso},sigma_a(T),0 <,rm {dim},(T-lambda)^ {-1}(0) 0 (M C )上的宝丽来,B是π上的宝丽来 a 0 (B),然后是s a (M C )s aw (M C )= p a 0 (M C )sigma_a(M_C)反斜杠sigma_ {aw}( M_C)= {pi ^ {a} _ {0}}(M_C)。
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