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Re: Understanding some issues on the denotational semantics

From: Juan Sequeda <juanfederico@gmail.com>
Date: Thu, 17 Feb 2011 10:10:50 -0600
Message-ID: <AANLkTik2Dy9FrdBmRjVDDKX38zbJDfRA2q_o0EiTUGm1@mail.gmail.com>
To: Alexandre Bertails <bertails@w3.org>
Cc: public-rdb2rdf-wg@w3.org
Is it me, or is the updated version that you are presenting [1] completely
different from the current version [2].

Your proposal is to replace [2] with [1] ?

Thanks for the clarification

[1] http://www.w3.org/2011/02/16-DM-denotational-rdf-semantics
[2] http://www.w3.org/TR/2010/WD-rdb-direct-mapping-20101118/#RDFdef

Juan Sequeda
+1-575-SEQ-UEDA
www.juansequeda.com


On Wed, Feb 16, 2011 at 2:14 PM, Juan Sequeda <juanfederico@gmail.com>wrote:

>
>
> On Wed, Feb 16, 2011 at 1:56 PM, Alexandre Bertails <bertails@w3.org>wrote:
>
>> On Wed, 2011-02-16 at 13:50 -0600, Juan Sequeda wrote:
>> > On Wed, Feb 16, 2011 at 1:26 PM, Alexandre Bertails <bertails@w3.org>
>> > wrote:
>> >         Hi Juan,
>> >
>> >         On Wed, 2011-02-16 at 13:15 -0600, Juan Sequeda wrote:
>> >         > Alex, Eric
>> >         >
>> >         >
>> >         > Can you guys clarify some issues that I'm not understanding
>> >         correctly.
>> >
>> >
>> >         It's funny you ask these things right after I sent [1] :-)
>> >
>> >
>> >
>> > Yes, what a coincidence. You sent your email 1 hour ago. I've been
>> > working on this for the last two.
>> >
>> >         I suggest you follow [2] instead of what you found in the
>> >         current draft.
>> >         This is an updated version (far simpler and much more
>> >         complete) and I'll
>> >         be happy to help you going through it.
>> >
>> >
>> > Damn.. 2 hours of work down the drain....
>>
>> Sorry for that :-/
>>
>
> Np. Not your fault ;)
>
>>
>> One good indication of our work is to follow the activity on the
>> repository. We don't produce the maths without having the corresponding
>> code and tests. This part is now living in the "no_hierarchy" branch but
>> I plan to merge that into the default one in the next days. That will
>> also update the web application but this will be transparent, as both
>> branches pass exactly the same test-suite.
>>
>
> ok
>
>>
>> Alexandre.
>>
>>
>> >
>> >
>> >         Alexandre Bertails.
>> >
>> >         [1] http://www.w3.org/mid/1297880900.11894.25.camel@simplet
>> >         [2] http://www.w3.org/2011/02/16-DM-denotational-rdf-semantics
>> >
>> >
>> >         >
>> >         >
>> >         > Thanks!
>> >         >
>> >         >
>> >         > I'm going to use this as my
>> >         > example:
>> >
>> http://www.w3.org/TR/2010/WD-rdb-direct-mapping-20101118/#lead-ex
>> >         >
>> >         >
>> >         > First, I'm going to define a Database Model, following:
>> >         >
>> >         http://www.w3.org/TR/2010/WD-rdb-direct-mapping-20101118/#Rel
>> >         >
>> >         >
>> >         > Database = {"Address -> Table1, "People" -> Table2}
>> >         >
>> >         >
>> >         > Table1 = (Header1, 0, [id], 0, Body1)
>> >         > Header1 = {id -> int, city -> char, state ->char}
>> >         > Body1 = [Tuple1, Tuple2]
>> >         > Tuple1 = {id -> 18, city -> Cambridge, state -> MA}
>> >         > Tuple2 = {id -> 19, city -> Austin, state -> TX}
>> >         >
>> >         >
>> >         > Table2 = {Header2, 0, [id], FK2, Body2)
>> >         > Header2 = {id -> int, fname -> char, addr -> int}
>> >         > FK2 = { [addr] -> (Table1, [id]) }
>> >         > Body2 = [Tuple3, Tuple4, Tuple5]
>> >         > Tuple3 = {id -> 7, fname -> Bob, addr -> 18}
>> >         > Tuple4 = {id -> 8, fname -> Sue, addr -> null}
>> >         > Tuple5 = {id -> 9, fname -> Joe, addr -> 19}
>> >         >
>> >         >
>> >         > So lets start!
>> >         > [23]
>> >         > directDB()
>> >         > ≝
>> >         > { directR(R, M) ∣
>> >         > R ∈ DB }
>> >         >
>> >         >
>> >         > First of all, I do not know what M is. I'm assuming that DB
>> >         is the
>> >         > Database, therefore:
>> >         >
>> >         >
>> >         > R = {"Address -> Table1, "People" -> Table2}
>> >         >
>> >         >
>> >         > If I understand the notation correctly, then:
>> >         >
>> >         >
>> >         > directDB() = {directR("Address -> Table1, M),
>> >         directR("People" ->
>> >         > Table2, M)}
>> >         >
>> >         >
>> >         > so let's do the first directR
>> >         >
>> >         >
>> >         > 24]
>> >         > directR(R, M)
>> >         > ≝
>> >         > { directT(T, R,
>> >         > M) ∣ T ∈ R.Body }
>> >         >
>> >         > I'm still unclear what is M
>> >         >
>> >         >
>> >         > What is R.Body? I'm assuming you are retrieving Body.
>> >         Therefore Body
>> >         > of Table1 is [Tuple1, Tuple2], therefore I assume:
>> >         >
>> >         >
>> >         > T = [Tuple1, Tuple2]
>> >         >
>> >         >
>> >         > now we have:
>> >         >
>> >         >
>> >         > directR("Address -> Table1, M) = { directT([Tuple1, Tuple2],
>> >         "Address
>> >         > -> Table1, M) }
>> >         >
>> >         >
>> >         > now let's go to the definition of directT
>> >         >
>> >         >
>> >         > 25]
>> >         > directT(T, R, M)
>> >         > ≝
>> >         > { directS(S, T,
>> >         > R, M) ∣ S =
>> >         > subject(T, R,
>> >         > M) }
>> >         >
>> >         >
>> >         > now we need to know what is S
>> >         >
>> >         >
>> >         > 26]
>> >         > subject(T, R, M)
>> >         > ≝
>> >         > if (pk(R) =
>> >         > ∅) then new blank
>> >         > node else rowIRI(R, T[pk(R)]) # references the ultimate
>> >         referent of hierarchical key
>> >         >
>> >         >
>> >         > What is pk(R)?
>> >         >
>> >         >
>> >         > now we have:
>> >         >
>> >         >
>> >         > subject([Tuple1, Tuple2], "Address -> Table1, M) = if
>> >         (pk("Address ->
>> >         > Table1) = 0
>> >         >
>> >         >          then new blank node
>> >         >
>> >         >      else
>> >         >
>> >         >          rowIRI("Address -> Table1, T[pk("Address ->
>> >         Table1)])
>> >         >
>> >         >
>> >         >
>> >         >
>> >         > I'm assuming tat pk("Address -> Table1) will return the
>> >         primary key,
>> >         > then we have
>> >         >
>> >         >
>> >         > pk("Address -> Table1) = [id]
>> >         >
>> >         >
>> >         > Now we have
>> >         >
>> >         >
>> >         > subject([Tuple1, Tuple2], "Address -> Table1, M) =
>> >         rowIRI("Address ->
>> >         > Table1, T[[id]])
>> >         >
>> >         >
>> >         > Now let's go to the definition of rowIRI
>> >         >
>> >         >
>> >         > [31]
>> >         > rowIRI(R, As)
>> >         > ≝
>> >         > IRI(UE(R.name) +
>> >         > "/" + (join(',',
>> >         > UE(A.name) + "="
>> >         > + UE(A.value)) ∣
>> >         > A ∈ As ) + "#_")
>> >         >
>> >         >
>> >         > What is UE()?
>> >         >
>> >         >
>> >         > What is R.name? Where is it defined?
>> >         >
>> >         >
>> >         > Ok, I'm stopping here.
>> >         >
>> >         >
>> >         > p.s. By the time I finished doing all of this, I saw that
>> >         Alex sent an
>> >         > email with a new version of the denotational semantics. I'm
>> >         guessing I
>> >         > should re-do what I just did with the new version?
>> >         >
>> >         >
>> >         > Thanks guys for the clarifications!
>> >         >
>> >         >
>> >         > Juan Sequeda
>> >         > +1-575-SEQ-UEDA
>> >         > www.juansequeda.com
>> >         >
>> >         >
>> >
>> >
>> >
>> >
>>
>>
>>
>
Received on Thursday, 17 February 2011 16:11:44 GMT

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