Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!

 



Forgot your password?
typodupeerror

Comment Re:Uforgiveable (Score 1) 232

Therac 25 teaches us that mechanical interlocks and switches are a good thing. The probability of failure of a well designed switch (1e-5 to 1e-6) is a lot lower and better analyzed than the probability of failure of half baked (or any kind of) software.

Making the final output of the system go through a mechanical switch for a real alert means that the system can't send a real alert without the switch being closed e.g. the signal path is physically open at the switch. P(false alert)=P(software fails)*P(switch fails)

If you feed the output of the switch through possibly defective software, you've changed the equation to P(failure)=P(software fails)+P(switch fails) which is similar to what caused the Challenger disaster.

In Challenger, the two seals on the booster rockets were deemed redundant with independent failure probabilities P(failure)=P(fail_seal1)*P(fail_seal2) however a common failure path for both seals,low temperature, was overlooked giving the equation as roughly P(failure)=P(fail_seal1)+P(fail_seal2).

Since the probability of the switch failing is near zero, with the switch in place as the sole last step, the chance of a false alert is near zero. If the switch is read by software then the chance of sending a false alert reverts to the failure percentage of the software negating the value of adding a switch to begin with .

Comment Alfresco (Score 1) 212

In a past life, I setup the free version of Alfresco for my teams. Configuration can be tough for those who don't like insanely deep trees of config files but it has a nice webdav server which integrates with the rest of it's quite awesome versioning capabilities. It's great for versioning anything that isn't source code.

Comment Re:Graph was 4-colorable... (Score 3, Interesting) 55

I actually found this story quite useful as the references it gave showed that some of the problems they solved are very similar to a research problem that I am working on in electron microscopy. That being said, the article was very technical and outside of my understanding in some of the more video game related areas. I'm happy to see this on slashdot.

Comment Re:Hint taken. (Score 3, Informative) 519

The Federal Law also allows state attorneys general to file suit on behalf of tax papyers in credit reporting cases. A local lawn care service accidentally submitted an already paid bill of mine to a collections agency. The Alabama Attorney General's Office was not amused and forced them to write a letter explaining themselves to me and then suggested that I sue the company which by then had seen the error in their ways.

Comment Re:Capitalism. (Score 2) 81

In a Venture Capital funded startup, the VC puts up the original money. Taking the company public swaps the capital provided by the VC for capital provided by the public in the IPO. Publicly traded stock does little once the company is started unless new shares are issued after the company goes public.

Slashdot Top Deals

Ocean: A body of water occupying about two-thirds of a world made for man -- who has no gills. -- Ambrose Bierce

Working...