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Comment: Power and maintenance? (Score 3, Interesting) 211

by lemaymd (#26153625) Attached to: How To Build a Homebrew PS3 Cluster Supercomputer
Researchers pay not only for the initial capital outlay required to install a supercomputer, but also for its power, cooling, the building it resides in, and its maintenance. This PS3 cluster might be cheap from the researchers' standpoint if they don't pay for any of these things directly, but I imagine their departments won't be real thrilled if a bunch of researchers start building their own individual "cheap" supercomputers! Those issues aside, it sounds like they're doing pretty cool stuff with those machines, so maybe more supercomputers should be cell-based!

Comment: Claim of formal verification too grand (Score 1) 94

by lemaymd (#25278175) Attached to: NSA Open Sources Tokeneer Research Project
From the full report: "The aim of this activity is to capture the system security properties unambiguously. These security properties are the key system properties that must hold of the system in order for it to satisfy its security obligations. The security properties were expressed using the Z notation; the same notation as was used for the Formal Specification. The security properties were captured as proof obligations on the Formal Specification, so the same level of abstraction and context was used for expression of the security properties as was used in producing the Formal Specification. By using the notation and context of the Formal Specification it was possible to prove that the Formal Specification exhibits the Security Properties. The proof took the form of an informal justification, with a discussion of the arguments required to perform each stage of the proof. EAL5 does not demand proof of these properties, but a sample of the properties were proved to be held by the specification, and then later by the code. At the higher levels of certification such proofs are necessary, and can be carried out either rigorously by hand or using tool support."

Round Numbers are always false. -- Samuel Johnson