When greediness fails: examples from stochastic scheduling

When greediness fails: examples from stochastic scheduling

The purpose of this paper is to present examples for the sometimes surprisingly di/erent behavior of deterministic and stochastic scheduling problems. In particular, it demonstrates some seemingly counterintuitive properties of optimal scheduling policies for stochastic machine scheduling problems. c © 2003 Elsevier B.V. All rights reserved.

When Bellman's Principle Fails

We present several examples which show that the well known statements about Markov Decision Processes can fail if the loss function is not bounded.

When Sharing Fails

When Abstraction Fails

Reasoning about programs is mostly deduction: the reasoning from the abstract model to the concrete run. Deduction is useful because it allows us to predict properties of future runs—up to the point that a program will never fail its specification. However, even such a 100% correct program may still show a problem: the specification itself may be problematic, or deduction required us to abstrac...

When face recognition fails.

Two studies investigated recognition of pictures of faces, focusing on the effects of changes in appearance of the face from presentation to test and type of processing or encoding. Experiment 1 demonstrated that (a) previously seen faces changed in pose and facial expression were discriminated from "new" faces essentially as well as pictures identical at presentation and test; (b) major change...