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.


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