Is there a non-deterministic version of the complexity class PP?
Clash Royale CLAN TAG#URR8PPP
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From a quick skim of the literature (and complexity zoo), there doesn't seem to be a non-deterministic version of PP. Is there a reason for this (e.g. PP=non-deterministic PP?)
cc.complexity-theory complexity-classes time-complexity
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up vote
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From a quick skim of the literature (and complexity zoo), there doesn't seem to be a non-deterministic version of PP. Is there a reason for this (e.g. PP=non-deterministic PP?)
cc.complexity-theory complexity-classes time-complexity
How would such a complexity class be defined?
– Sasho Nikolov
8 hours ago
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up vote
2
down vote
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From a quick skim of the literature (and complexity zoo), there doesn't seem to be a non-deterministic version of PP. Is there a reason for this (e.g. PP=non-deterministic PP?)
cc.complexity-theory complexity-classes time-complexity
From a quick skim of the literature (and complexity zoo), there doesn't seem to be a non-deterministic version of PP. Is there a reason for this (e.g. PP=non-deterministic PP?)
cc.complexity-theory complexity-classes time-complexity
cc.complexity-theory complexity-classes time-complexity
asked 10 hours ago
user138901
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334
How would such a complexity class be defined?
– Sasho Nikolov
8 hours ago
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How would such a complexity class be defined?
– Sasho Nikolov
8 hours ago
How would such a complexity class be defined?
– Sasho Nikolov
8 hours ago
How would such a complexity class be defined?
– Sasho Nikolov
8 hours ago
add a comment |Â
2 Answers
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PP is defined as a probabilistic class and we don't normally think of nondeterministic versions of any of these classes (as far as I'm aware). In a sense probabilistic classes and nondeterministic ones are already on the same spectrum -- let me illustrate. We can define a language to be in PP if there's a randomized poly-time TM ("RPTM") that on a yes instance accepts with $> 0.5$ probability and on a no instance accepts with $leq 0.5$ probability. Similarly we can define a language to be in NP if there's a RPTM accepting yes-instances w.prob $> 0$ and accepting no-instances w.prob $0$. (Convince yourself of this if you haven't before.) BPP corresponds to probability thresholds $geq 2/3$ and $leq 1/3$ while RP corresponds to $geq 1/2$ and $0$.
So you see, PP can already be viewed as a "nondeterministic" version of P, but with different requirements as compared to NP.
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up vote
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It does not really make sense to define an “X-version of class Yâ€Â, this is a misguided viewpoint. You define classes because they are useful or interesting in whatever context you are investigating, not to fill a slot in an imaginary table. So, what would count as a nondeterministic version of PP depends very much on what you intend to do with the class.
Having said that, in view of $mathrmP^=PP$, one reasonable option is to define a nondeterministic version of PP as $mathrmNP^$. Actually, this should equal $existsmathrmPP$.
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
up vote
4
down vote
PP is defined as a probabilistic class and we don't normally think of nondeterministic versions of any of these classes (as far as I'm aware). In a sense probabilistic classes and nondeterministic ones are already on the same spectrum -- let me illustrate. We can define a language to be in PP if there's a randomized poly-time TM ("RPTM") that on a yes instance accepts with $> 0.5$ probability and on a no instance accepts with $leq 0.5$ probability. Similarly we can define a language to be in NP if there's a RPTM accepting yes-instances w.prob $> 0$ and accepting no-instances w.prob $0$. (Convince yourself of this if you haven't before.) BPP corresponds to probability thresholds $geq 2/3$ and $leq 1/3$ while RP corresponds to $geq 1/2$ and $0$.
So you see, PP can already be viewed as a "nondeterministic" version of P, but with different requirements as compared to NP.
add a comment |Â
up vote
4
down vote
PP is defined as a probabilistic class and we don't normally think of nondeterministic versions of any of these classes (as far as I'm aware). In a sense probabilistic classes and nondeterministic ones are already on the same spectrum -- let me illustrate. We can define a language to be in PP if there's a randomized poly-time TM ("RPTM") that on a yes instance accepts with $> 0.5$ probability and on a no instance accepts with $leq 0.5$ probability. Similarly we can define a language to be in NP if there's a RPTM accepting yes-instances w.prob $> 0$ and accepting no-instances w.prob $0$. (Convince yourself of this if you haven't before.) BPP corresponds to probability thresholds $geq 2/3$ and $leq 1/3$ while RP corresponds to $geq 1/2$ and $0$.
So you see, PP can already be viewed as a "nondeterministic" version of P, but with different requirements as compared to NP.
add a comment |Â
up vote
4
down vote
up vote
4
down vote
PP is defined as a probabilistic class and we don't normally think of nondeterministic versions of any of these classes (as far as I'm aware). In a sense probabilistic classes and nondeterministic ones are already on the same spectrum -- let me illustrate. We can define a language to be in PP if there's a randomized poly-time TM ("RPTM") that on a yes instance accepts with $> 0.5$ probability and on a no instance accepts with $leq 0.5$ probability. Similarly we can define a language to be in NP if there's a RPTM accepting yes-instances w.prob $> 0$ and accepting no-instances w.prob $0$. (Convince yourself of this if you haven't before.) BPP corresponds to probability thresholds $geq 2/3$ and $leq 1/3$ while RP corresponds to $geq 1/2$ and $0$.
So you see, PP can already be viewed as a "nondeterministic" version of P, but with different requirements as compared to NP.
PP is defined as a probabilistic class and we don't normally think of nondeterministic versions of any of these classes (as far as I'm aware). In a sense probabilistic classes and nondeterministic ones are already on the same spectrum -- let me illustrate. We can define a language to be in PP if there's a randomized poly-time TM ("RPTM") that on a yes instance accepts with $> 0.5$ probability and on a no instance accepts with $leq 0.5$ probability. Similarly we can define a language to be in NP if there's a RPTM accepting yes-instances w.prob $> 0$ and accepting no-instances w.prob $0$. (Convince yourself of this if you haven't before.) BPP corresponds to probability thresholds $geq 2/3$ and $leq 1/3$ while RP corresponds to $geq 1/2$ and $0$.
So you see, PP can already be viewed as a "nondeterministic" version of P, but with different requirements as compared to NP.
answered 4 hours ago
usul
5,01911435
5,01911435
add a comment |Â
add a comment |Â
up vote
2
down vote
It does not really make sense to define an “X-version of class Yâ€Â, this is a misguided viewpoint. You define classes because they are useful or interesting in whatever context you are investigating, not to fill a slot in an imaginary table. So, what would count as a nondeterministic version of PP depends very much on what you intend to do with the class.
Having said that, in view of $mathrmP^=PP$, one reasonable option is to define a nondeterministic version of PP as $mathrmNP^$. Actually, this should equal $existsmathrmPP$.
add a comment |Â
up vote
2
down vote
It does not really make sense to define an “X-version of class Yâ€Â, this is a misguided viewpoint. You define classes because they are useful or interesting in whatever context you are investigating, not to fill a slot in an imaginary table. So, what would count as a nondeterministic version of PP depends very much on what you intend to do with the class.
Having said that, in view of $mathrmP^=PP$, one reasonable option is to define a nondeterministic version of PP as $mathrmNP^$. Actually, this should equal $existsmathrmPP$.
add a comment |Â
up vote
2
down vote
up vote
2
down vote
It does not really make sense to define an “X-version of class Yâ€Â, this is a misguided viewpoint. You define classes because they are useful or interesting in whatever context you are investigating, not to fill a slot in an imaginary table. So, what would count as a nondeterministic version of PP depends very much on what you intend to do with the class.
Having said that, in view of $mathrmP^=PP$, one reasonable option is to define a nondeterministic version of PP as $mathrmNP^$. Actually, this should equal $existsmathrmPP$.
It does not really make sense to define an “X-version of class Yâ€Â, this is a misguided viewpoint. You define classes because they are useful or interesting in whatever context you are investigating, not to fill a slot in an imaginary table. So, what would count as a nondeterministic version of PP depends very much on what you intend to do with the class.
Having said that, in view of $mathrmP^=PP$, one reasonable option is to define a nondeterministic version of PP as $mathrmNP^$. Actually, this should equal $existsmathrmPP$.
answered 2 hours ago


Emil Jeřábek
10.3k33459
10.3k33459
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How would such a complexity class be defined?
– Sasho Nikolov
8 hours ago