Re: The original version

On Jan 11, 12:53 am, vldm10 <vld..._at_yahoo.com> wrote:
> Example: Let E1 and E2 be two entities of the same type. Suppose they
> change the value of their properties. It is quite clear that this can
> happen at the same time and that E1 and E2 can have all of the exact
> same attributes. That which is very bad for Anchor Modeling here is
> that the identities of these two entities are different, even though
> these two entities are exactly the same in the database, and in the
> real world.
>
> In this example, a variety of combinations and variations can occur,
> especially since the authors of Anchor Modeling allow the deletion of
> erroneous data.
>
> Vladimir Odrljin

In my message 25, from Jan 9 2011, I wrote that in the first version of the paper "Anchor Modeling" which was written in 2009, I could not find reference [19] on the given web address. I have now found it, but it seems the reference was moved to the new version of Anchor Modeling from 2010 and new web address. The corresponding reference is [25]. In [25] the authors write that they use the surrogate key. See page 2 : “Hatt(C,D,T) contains, as indicated above an anchor surrogate key”.

(i) “Anchor Modeling” is based on the 6NF, which is evident from the title: “Anchor Modeling an agile modeling technique using sixth normal form for structurally and temporally evolving data”. In this thread in my message from Oct 5, 2010, I presented the case of a relation that has mutually independent attributes. In this example the whole relation is in 6NF. So here “Anchor Modeling” would not work. This means that Anchor Modelling is not based on 6NF and that, in fact, its basis is unknown.

"Anchor Modeling" starts at the conceptual level with structures. However, the authors have not proven that we can get (for example) the concept of the corresponding entity from these structures. So we can pose the question, why should anyone believe “Anchor Modeling”?

In “Anchor Modeling” the authors extensively use the transition from one data model to another data model. But they neither explain nor define this transition.
In my message in the thread from Oct 5, 2010 I wrote that this problem was solved in my paper from 2008. I used binary structures and the following two mappings: the first mapping is a schema mapping, and the second mapping is between instances of the data models. In this situation both models have the same semantics. I believe that this is an important result. (see also my message 16, from August 6, 2010)

(ii) Let E1 be the entity in the "Anchor Model" whose anchor key = 234 and which has three attributes that in time t1 have the values v1, v2, v3 respectively. One can insert another entity whose anchor key = 567 and whose three attributes at the same time t1 have again the values v1, v2, v3 respectively.
So we get two entities which have the same attribute values in the database. This implies that we have two entities in the real world, which have the same attributes in the time t1. These two entities have different surrogate keys. We know that this is nonsense in the ER model and Relational model. But we also see that "Anchor Model" supports this nonsense. So anybody can enter the same entities with different suroggates.
In this example, a variety of combinations and variations can occur, especially since the authors of Anchor Modeling allow the deletion of erroneous data.

(iii) Today the vast majority of keys use the industry standard, probably more than 90% of databases use this type of keys. For example, VIN, Bank account, SSN, etc. In this case too "Anchor Modeling" does not make sense.

(iv) The authors of "Anchor Model" did not show "meta data" in their solutions. In fact "Anchor Model" cannot solve structures with "meta data".

Vladimir Odrljin Received on Fri Mar 11 2011 - 03:28:53 CET