Notes FRBR WEMI entities, physicality, interchangeability, merging

Originally coming out of a discussion on Code4lib and RDA-L between me, Karen Coyle, and others (too many others).  Response rewritten for this forum.

Please keep in mind that of the Work, Entity, Manifestation, Item entity model, it’s really only Item that is an actual physical thing. All the others are abstract things, that I continue to believe are most easily thought of as sets of the things “below” them.

In traditional library cataloging, Items of the same Manifestation are considered interchangeable for our patrons. This is why we generally do not catalog below the Manifestation level, at the Item level.  On the other hand, in some circumstances for rare books catalogers, items of the same manifestation are NOT interchangeable for their users, and this is why (I am led to believe) rare books catalogers sometimes DO catalog at the Item level).

Compare to an Amazon book page. When you look at an Amazon web page for “a book”, they REALLY mean they have dozens, hundreds or thousands of actual physical books in some warehouses somewhere they can sell you. But there isn’t a page for each Item, Amazon too considers items of the same manifestation generally interchangeable for it’s users, you don’t generally get to pick WHICH Item sitting in a warehouse you get. The typical Amazon page basically represents a Manifestation, as the typical traditional library catalog page does.

(But if you ordered a book on Amazon and they sent you the book translated in a different language, or in digital form on an Apple II 5.25″ floppy disk, or in the 1986 first edition when you ordered the 2009 fifth — you’d be pissed!  All those things might be in the same Work or Expression, but for Amazon customers and for library users, Items from the same Work or Expression are not neccesarily interchangeable.)

So you can kind of get away with considering a Manifestation to be a real thing and talking about something “being” a manifestation, but it’s always good to remember that even a Manifestation is really an abstract set composed of a bunch of items.

But if you start thinking that an item in your hand can “be” a Work or Expression without “being” a Manifestation (and item!) too, you are setting yourself up for a lot of confusion.    You can’t have a Work or Expression (or, technically Manifestation), without having all the things below it, up to Item.

Okay, so maybe there ARE a few edge case exceptions.  Someone in a listserv conversation once suggested that if there’s a movie that is in pre-production, but nothing’s been filmed yet, maybe even a script hasn’t been written yet, maybe that Work exists, even though no Expressions, Manifestations, or Items of it do yet.  Maybe an IMDB page for a pre-production movie represents a Work for which there are no E M or I.  Could be useful to model things that way, sure, why not.  But bear in mind that even in that weird case, you don’t have any item in your hand!  The movie that hasn’t been made yet is a  purely conceptual non-physical thing, so okay maybe it’s “just” a Work. As soon as you have something in your hands (a script, a daily DVD), you’ve got an Item. Which belongs to a Manifestation set, which belongs to an Expression set, which belongs to a Work Set.

That’s the way the FRBR WEMI entity model is intended, and that’s the only useful way I can figure out to think about it. If you forget this in your modelling, I think you wind up with poorly modelled unuseful data.

In a conversation with Karen Coyle on the lists, I think perhaps she was forgetting or getting confused about this, and in the process accurately recognizing that if you DO get confused about this, you wind up with data that’s tricky to use and reconcile and merge with other data.My response edited for this forum.

Karen Coyle wrote:

I think this becomes a question of how we express WEMI — you can always link from/to any WEMI using “contains” or “contained in” — so you can always link to all of the Works in an aggregate. What I would like to achieve is for different decisions (like one community calling the aggregate a Work/Expression and another focusing on the individual works and linking those to a Manifestation) to not create incompatible data.

Keep in mind that EVERY item-in-hand MUST be a Manifestation. At least this is my interpretation of FRBR.

If you have a bound volume that’s an “aggregate”, it HAS to be a manifestation. (as I argued above in this blog post)

So there’s no way to “call an aggregate a Work/Expression” instead of a manifestation, if that aggregate is an actual physical item in your hand.

You’ve got a manifestation whether you like it or not. The question is how much “authority work” are you going to do on identifying the Expression and Work it belongs to. If you don’t do much because it doesn’t make sense for you to do so, maybe it starts out modelled as a manifestation just belonging to a “dummy” Expression/Work that contains only that Manifestation. Some other cataloger somewhere else does the “authority” work to flesh out an Expression and/or Work that maybe contains multiple manifestations or maybe doesn’t. Is your data incompatible? Not really, it can be merged simply by recognizing that your “dummy” Expression/Work can be merged into their more fleshed out one.

There’s also a question of how much “authority work” you want to do on the _contents_ of the aggregate. Maybe you don’t want to spend any time on that “analytical” task at all, and your record does not reveal that the item in your hand IS an aggregate, it does not actually expose relationships to the other Works/Expressions contained within. It might have a transcribed table of contents as an attribute only, not as a relationship to other entities. Later some other cataloger fleshes that out. Here too, that other catalogers extra work can be (conceptually at least) easily “merged in” to your record, there is no incompatibility.

[If two different catalogers/communities decide that two different Works contain _different_ manifestations, and violently disagree, then THAT’s an incompatibility that’s harder to resolve and is a legitimate concern. But that’s not what we have in this example, which is quite straightforward.]

I’ve had this ill-formed notion for a while that we shouldn’t actually  be creating WEMI as “things” — that to do so locks us into a record  model and we get right back into some of the problems that we have  today in terms of exchanging records with anyone who doesn’t do things  exactly our way. WEMI to me should be relationships, not structures.  If one community wants to gather them together for a particular  display, that shouldn’t require that their data only express that  structure. I’m not sure FRBR supports this.

sound vague? it is — I wish I could provide something more concrete,  but that’s what I’m struggling with.

While to some extent I sympathize with your inchoate thoughts about modelling WEMI being a mistake, and we’ve talked about that before — ultimately I still disagree. It is appropriate to use an entity-relation-attribute model to come up with the kind of explicit and formal model of our data that we both agree we need. It’s a conventional, mature, and well-tested modelling approach (I wouldn’t want to pin all our eggs to RDF experimentation that at least arguably does not rely on an entity model).

You can’t have an entity model without entities. The FRBR WMI (and more debatably E) entities are the ones that clearly come out of a formalization of our 100 year tradition of cataloging, meaning there’s probably something to them AND that using them makes retroactively applying the model to our 100 years worth of legacy data is more feasible (and BOTH of those facts are totally legitimate grounds for decision making. And the decision has already been made too, although in the case of FRAD I’d still be reluctant to accept it as a “done deal”, but in the case of FRBR, it is much better done, a much more useful and accurate abstraction of our cataloging tradition).

But you’re right that neither Work, Expression or Manifestation are “things” if you mean physical things.  They are abstract things, they are sets of physical things, that it is useful for us to model so we can say things about them (including but not limited to which physical things are a member of them). It’s often useful to say things about things that aren’t physical things you can hold in your hand too.

If ALL you have are assertions about Manifestations (or worse Items!), then you’re going to end up duplicating a lot of assertions (see, I’m avoiding talking about records!) to assert something  about every manifestation that belongs to the same Work, when your assertion is REALLY about the Work.   A certain movie is a film adaptation of a certain work. Do you really need to make a bunch of  RDF triples asserting that it’s a film adaptation of EVERY manifestation (or every single Item, every copy on someone’s shelves!) that exists of that Work?  No, and it’s not even true, it’s not neccesarily an adaptation of any particular edition/manifestation (or if it is, you might know which one), it’s an adaptation of the Work.

We model the Work as an entity so we can make assertions about it, whether in records or in free-floating RDF assertion fantasy land. We can assert once that a film is an adaptation of a work, and we can assert that a bunch of manifestations/editions are all manifestations of that work (belong to that work-set), and then we can know that all of those Manifestations belong to the Work that was adapted into that film.

5 thoughts on “Notes FRBR WEMI entities, physicality, interchangeability, merging

  1. Jonathan, I obviously have no problem with using an E-R model. The discussion on RDA-L was about the fact that different communities will make different decisions on the description of W E M — as we saw with the music example sent by Jenn. Perhaps you could take her example ( linked from the email she originally sent out) and compare it to how RDA would model it (with the music CD as the expression), and then look at what that might mean for compatibility. The question then becomes: Is it inherent in the FRBR model that all published aggregations must be described as single expressions? RDA says Yes, Jenn says No. And that is followed by the question: So, is this going to be a problem when we try to implement FRBR-ized data?

  2. Not sure if I understand the question “Is it inherent in the FRBR model that all published aggregations must be described as single expressions.”

    I think it is inherent in FRBR that any physical item in your hand _can be modelled as_ an Item which belongs to a Manifestation set which belongs to an Expression set, which belongs to a Work Set. Whether or not it’s an “aggregate”. [I believe Jenn would agree with me here, but we could ask her].

    It’s not necessarily inherent in FRBR that any given system has to actually flesh out those hypothetically existing entities. And if one doesn’t, I’m no seeing any problems based on that fact with implementing FRBRized data or comparing data between two different communities, as I tried to explain above.

    What is not unclear in FRBR is how to handle relationships in the sense of: Can a Manifestation include within it several pieces that belong to DIFFERENT expressions/works/manifestations than the item-in-hand belongs to?

    I believe Jenn’s modelling answers yes, and I believe this is in fact the only sane way to deal with it, which, if you deal with it that way, also provides no conceptual problems with integrating “FRBRized” data from different sources. (The fact that Jenn has actually developed a working system is to her argument’s credit too. Working systems are the tests of our modelling hypothesis, no?)

    (Note again that just because something CAN be modelled doesn’t mean it HAS to be in a given system; “blanks” can be left to be filled in later. But it means if you want to draw out/assert about those aspects, this is how you do it. If you don’t, you don’t.)

    If there are problems you see either of these things providing for integrating data from different sources, I do not yet understand what you’re seeing.

  3. “It’s not necessarily inherent in FRBR that any given system has to actually flesh out those hypothetically existing entities.” That’s what I hope, but I’m not sure there is agreement about that in the RDA world. So it would be good to ask: Can you create a manifestation with no linked Expression and no linked Work?

    “I think it is inherent in FRBR that any physical item in your hand _can be modelled as_ an Item which belongs to a Manifestation set which belongs to an Expression set, which belongs to a Work Set. Whether or not it’s an “aggregate”. ”

    If you have “an” expression set and “a” work set, then I think you are following the RDA one-to-one model between Expressions and Manifestations. But to me it is this belonging to a set, rather than having relationships, which is the problem. Belonging to a set gets that hierarchical thing going, and I think that’s the rub.

    Clarification: “So there’s no way to “call an aggregate a Work/Expression” instead of a manifestation, if that aggregate is an actual physical item in your hand.”

    It’s not “instead of” — in the RDA discussion, the statement was that when you have a manifestation (or call it an instance of a manifestation, thus “item”) in hand, and it has more than one identifiable intellectual “bit,” you must describe an expression that is one-to-one with that manifestation. So I think it goes like this:

    W: Moby Dick
    E1: Moby Dick (published alone)
    M1: Moby Dick, published by X in 1936
    M2: Moby Dick, published by Y in 1954

    Now I come along and I’ve got in hand another publication of Moby Dick, only this one has a preface by J Smith and includes two appendices and a poem by Hart Crane. Using the RDA rules, this gives me:

    W: Moby Dick
    E1: Moby Dick (published alone)
    M1: Moby Dick, published by X in 1936
    M2: Moby Dick, published by Y in 1954
    E2: Moby Dick, with preface, appendices and Hart Crane
    M1: Moby Dick with preface, appendices and Hart Crane, published by Z in 2002

    Does this make sense to you? To me it says: This publication that has four parts, Moby Dick, preface, appendices and Hart Crane, is an Expression of W: Moby Dick. Or at least, that’s what it seems to say if you look at the WEM as containers, and this latter contains these four separate “bits” which we now must consider a single “bit.” But it’s rather obvious to me that the single “bit” is NOT an expression of W:, but could contain an expression of W:.

    So now I think I can try to explain why I don’t like seeing WEM as containers, sets, or “records” (which is how I think many people think of them). If E is a container that has four parts, it cannot be an Expression of something that is only one of those parts. If E is instead a set of possible relationships, it can have an expression to work relationship with the Work without declaring that it is itself and as a whole AN expression of the Work. Which would then mean that your manifestation could be a manifestation of a composite expression, as well as/or a manifestation of an expression of Moby Dick by itself, as well as/or a manifestation of an expression of Hart Crane’s poem.

    Part of my difficulty is that WEMI is often viewed as being a hierarchy, rather than a web of relationships. And this treatment that I am perceiving in RDA seems very hierarchical. It wants to model a top-to-bottom bibliographic view, and that view is based on the container (the item in hand). If followed strictly, it gives us exactly what we have today in AACR2 and MARC:

    100: Melville, H
    240: Moby Dick
    245: Moby Dick/ with preface by ….

    I realize this is getting a bit nutty, and maybe my brain went haywire when I did the big “6-0”. If I could explain it all better I’m sure you and I would understand each other by now, but my thoughts just won’t settle down toward a clear picture.

  4. Your diagram makes sense to me, but I think the answer to aggregates is that an expression CAN be part of more than one work, where “part” here means “contained in”. We have two different axes of relationships.

    An expression BELONGS TO (aka ‘is an expression of’, aka ‘is a realization of’ in official FRBR terminology which I don’t really like) only one work in formal FRBR, yes. But an expression (in my own opinion of the proper way to model aggregates, something which is still somewhat in play in FRBR), an expression can CONTAINED in a _different_ (aggregate) work than the one it “belongs to”, and can be contained in more than one (aggregate) work.

    Are you with me there, do we already agree on that, or not? Not sure.

    That part about “contained in” is not neccesarily official FRBR, it is _one_ way to treat aggregates in FRBR, but it’s not _inconsistent_ with FRBR, and my opinion it’s the only way to treat them that make sense.

    Does that make any sense? Or have I completely missed your point? If I understand your point, then the fact that an expression ‘contained in’ (a particular manifestation of a particular another expression of a particular work) is a different thing than an expression belonging to (being a realization of) it’s own work — eliminates the problem.

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