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101.
102.
Following Sam Payne?s work, we study the existence problem of nontrivial vector bundles on toric varieties. The first result we prove is that every complete fan admits a nontrivial conewise linear multivalued function. Such functions could potentially be the Chern classes of toric vector bundles. Then we use the results of Cortiñas, Haesemeyer, Walker and Weibel to show that the (non-equivariant) Grothendieck group of the toric 3-fold studied by Payne is large, so the variety has a nontrivial vector bundle. Using the same computation, we show that every toric 3-fold X either has a nontrivial line bundle, or there is a finite surjective toric morphism from Y to X, such that Y has a large Grothendieck group. 相似文献
103.
Peter Brucker Sigrid Knust Duncan Roper Yakov Zinder 《Mathematical Methods of Operations Research》2000,52(3):369-387
Problems with unit execution time tasks and two identical parallel processors have received a great deal of attention in
scheduling theory. In contrast to the conventional models, where each task requires only one processor, we consider a situation
when a task may require both processors simultaneously. For problems without precedence constraints we present several polynomial
time algorithms which complement recent results of Lee and Cai. We also show that the introduction of precedence constraints
leads to NP-hardness results for maximum lateness and mean flow time objective functions. For the maximum lateness problem,
a family of algorithms, based upon the idea of modified due dates, is considered. The worst case behaviour of these algorithms
is analysed, and it is shown that the same upper bound is tight for each algorithm of this family. 相似文献
104.
105.
106.
We prove a decomposition theorem for the cd-index of a Gorenstein* poset analogous to the decomposition theorem for the intersection cohomology of a toric variety. From this we settle a conjecture
of Stanley that the cd-index of Gorenstein* lattices is minimized on Boolean algebras. 相似文献
107.
Kalle M. Mikkola 《Integral Equations and Operator Theory》2006,55(2):249-271
A finite-dimensional linear time-invariant system is output-stabilizable if and only if it satisfies the finite cost condition, i.e., if for each initial state there exists at least one L2 input that produces an L2 output. It is exponentially stabilizable if and only if for each initial state there exists at least one L2 input that produces an L2 state trajectory. We extend these results to well-posed linear systems with infinite-dimensional input, state and output
spaces. Our main contribution is the fact that the stabilizing state feedback is well posed, i.e., the map from an exogenous input (or disturbance) to the feedback, state and output signals is continuous in Lloc2 in both open-loop and closed-loop settings. The state feedback can be chosen in such a way that it also stabilizes the I/O
map and induces a (quasi) right coprime factorization of the original transfer function. The solution of the LQR problem has
these properties. 相似文献
108.
A MRD CI procedure has been used to calculate several electronic states of the hydroperoxyl radical. The basis set is of double-zeta plus polarization quality augmented with s- and p-type bond and Rydberg functions. The vertical excitation energies of the lowest eight doublet and six quartet states are reported. Oscillator strengths for transitions form the ground to upper doublet states were calculated. A cut of the potential energy surfaces along the OOH fragmentation pathway is used to discuss the mechanisms of HO2 photodissociation below 6.4 eV. Arguments are presented which indicate O(1D) rather than O(3P) is the primary dissociation product, and so support the experimental findings rather than theory in the conflict raised earlier on this matter. Ostensibly the dissociation proceeds diabatically on the surface of the initially populated 2A″(1a″ → 2a″) state yielding OH(X2II) + O(1D). 相似文献
109.
110.