On Mon, Jul 28, 2008 at 11:10 AM, YKY (Yan King Yin) < [EMAIL PROTECTED]> wrote:
> On 7/28/08, Ben Goertzel <[EMAIL PROTECTED]> wrote: > > > > Your inference trajectory assumes that "cybersex" and "STD" are > probabilistically independent within "sex" but this is not the case. > > We only know that: > P(sex | cybersex) = high > P(STD | sex) = high > > If we're also given that > P(STD | cybersex) = 0 > then the question is moot -- it is already answered. > > It is a problem because we're not given the 3rd piece of information... > Yes, if there is no other background knowledge that is relevant, then this error is unavoidable. If however indirect background knowledge is available, such as the fact that "cyber-" often refers to things occurring online, then a reasoning engine may be able to incorporate this to guess that P(STD | cybersex) is small, which will then (if it is a confident conclusion) override the erroneous independence-assumption-based inference you cite. > > > PLN would make this error using the independence-assumption-based term > logic deduction rule; but in practice this rule is supposed to be overridden > in cases of known dependencies. > > > Why don't PLN use Pei-Wang-style confidence? PLN uses confidence values within its truth values, with a different underlying semantics and math than NARS; but that doesn't help much with the above problem... There is a confidence-penalty used in PLN whenever an independence assumption is invoked, but it's not that severe of a penalty -- and nor should it be. When additional evidence is not available, making an independence assumption is appropriate, even though sometimes it will turn out to be wrong. Ben ------------------------------------------- agi Archives: https://www.listbox.com/member/archive/303/=now RSS Feed: https://www.listbox.com/member/archive/rss/303/ Modify Your Subscription: https://www.listbox.com/member/?member_id=8660244&id_secret=108809214-a0d121 Powered by Listbox: http://www.listbox.com
