6 ms·
QIP = PSPACE
- poet 16y agoA link to the actual paper for those interested: http://www.cs.cmu.edu/~odonnell/hits09/jain-ji-upadhay-watrous-QIP-equals-PSPACE.pdf http://www.cs.cmu.edu/~odonnell/hits09/jain-ji-upadhay-watro....
- DanielRibeiro 16y agoPeople wondering how IP = PSPACE can delve further into the free draft of this great book on the subject: http://www.cs.princeton.edu/theory/index.php/Compbook/Draft http://www.cs.princeton.edu/theory/index.php/Compbook/Draft
- tocomment 16y agoDoes this mean quantum computers can't do anything classical computers can't? Does it let the air out of quantum computing? Or am I misreading?
- michaelty 16y agoCrap, we're still going to be using C when we get our flying cars!
- DanielRibeiro 16y agoNo. It means that, when solving harder problems (way beyond NP, as PSPACE is a really big class), it doesn't matter having a quantum computer.
- Dabacon 16y agoNo. It means that for the complexity class of interactive proofs quantum and classical are the same (when you ignore the number of rounds involved.) This doesn't tell us anything about whether quantum polynomial time equals classical polynomial time. The "IP" classes have problems that are very intractable...this basically says that for these very intractable problems quantum won't help (with the caveat that the quantum seems to allow fewer rounds in the interactive proof.)
- palish 16y agothe quantum seems to allow fewer rounds in the interactive proof This seems important. What if IP -> QIP is like O(N) -> O(log N)?
- Dabacon 16y agoThe result, IIRC, is that all of QIP can be done in three rounds, whereas if the same held in the classical world the polynomial hierarchy would collapse (which is considered about as likely as P=NP). Not of practical value, but it does point out that QIP is a slightly different beast than IP when you include the number of rounds.
- hypersoar 16y agoThis news (although not this particular link) was posted over a year ago. http://news.ycombinator.com/item?id=729335 http://news.ycombinator.com/item?id=729335
- Groxx 16y agohttp://en.wikipedia.org/wiki/IP_(complexity) http://en.wikipedia.org/wiki/IP_(complexity) Buh? Anyone care to explain what sort of problems would fall into this description?