Edward C. Zimmermann wrote: > On Thu, 9 Dec 2010 17:24:43 -0500, Denenberg, Ray wrote >> >> I want to try to break some of the recent discussion into smaller >> chunks. Can we focus in this thread on precision. To be honest, I >> don't really understand the issue, at least, not the requirement. Or >> perhaps, not the use case. >> >> Anyway ... >> >> I said >> '{1960,1961,1962,1963} - this means in effect "all of the >> (discrete) years, 1960 through 1963". It DOES NOT mean "the >> (continuous) interval 1960 through 1963"' > > From a purely logical view: > > {1960,1961,1962,1963,1964,1965,1966,1967,1968,1969} > is a decade: 10 years. That's the basic fallacy. A decade "is" not the set of its years, but it "consists of" the set of its years. Similar a day is more than the set of its hours, it's just another kind of concept. For instance your wedding day is neither an interval, nor a set of moments. Sure you can mathematically define dates in such a manner, but this completely removes the human aspect of dates (call it cultural, sociological or anything, but *not* "purely logical"). Without this aspect you can just use a simple model based points, intervals, and precisions in time, all defined by seconds. Computers do not need minutes, hours, days, month, years etc. Human perceptions of dates are different. > It can be viewed as: > - an interval 1960 to 1969 with a precision of year > - a date with the precision of decade > There is a subtle difference. Third it can be viewed as a set of years. Both the interval 1960 to 1969 and the decade *contain* the same years as the set above, but they are not identitcal to it. > The interval 1960-01-01/1969-12-31 is explicitly precise to day. > That any day included in 1960-01-01/1969-12-31 is also included > in 1960/1969 does not always mean that they say the same thing. > > We've talked about predicates "approx, questionable etc." and should > the following all be the same: > > - {1960,1961,1962,1963,1964,1965,1966,1967,1968,1969} > - the 1960s > - 1960/1969 > - 1960-01-01/1969-12-31 > > then the application of the predicate should say the same thing, right? > Do they? I think not. I neither. Jakob -- Jakob Voß <[log in to unmask]>, skype: nichtich Verbundzentrale des GBV (VZG) / Common Library Network Platz der Goettinger Sieben 1, 37073 Göttingen, Germany +49 (0)551 39-10242, http://www.gbv.de