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Ontology meets big data: immutability ODISE IV 4th International Workshop on Ontology ‐ Driven Information Systems Engineering Co-located with Formal Ontology.

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Presentation on theme: "Ontology meets big data: immutability ODISE IV 4th International Workshop on Ontology ‐ Driven Information Systems Engineering Co-located with Formal Ontology."— Presentation transcript:

1 ontology meets big data: immutability ODISE IV 4th International Workshop on Ontology ‐ Driven Information Systems Engineering Co-located with Formal Ontology in Information Systems 2012 Tuesday, 24th July Chris Partridge Chief Ontologist, BORO Solutions,

2 © 2012 BORO Solutions topics rationale big data: immutability ontology architecture change component not the whole story: need to consider epistemology two dimensional semantics bitemporal data architecture for epistemic change summary questions 2

3 rationale joined-up thinking opportunities for joining up an example: immutability 3

4 © 2012 BORO Solutions joined-up thinking 4 pureapplied “pure mathematics, may it never be of any use to anyone.” Henry John Stephen Smith ( ) toast to the Mathematical Society of England in Science, 10 Dec 1886 for some disciplines, there is a gap that is too wide to cross philosophy (ontology/ epistemology) enterprise computing immutability join ‘pure’ to ‘applied’

5 © 2012 BORO Solutions pure and applied: science and engineering how should they join up? the traditional joined-up view: science devises theories engineering works out whether and where it is useful to apply them may end up choosing different ‘best’ theories standard illustration civil engineers use Newtonian rather than Einsteinian theories to design bridges, etc. in other words, engineers can legitimately select a different ‘best’ theory from physicists but they select a theory from physics enterprise computing and ontology are not joined-up in this science- engineering way enterprise computing devises its own theory-lite solutions on ontological topics either there is something different about these disciplines or there are potentially opportunities for improvement one way to show they are not different is to identify an opportunity 5

6 © 2012 BORO Solutions opportunities for joining up how do we identify the joining up opportunities? no guarantee that: any particular topic in philosophy will be relevant to enterprise computing any particular theory in a topic will have utility in enterprise computing however, if one can find a topic that: enterprise computing has shown in useful, and ontology has matching theories then, this is likely to be an opportunity 6

7 © 2012 BORO Solutions an example: immutability offer ‘immutability’ as an example ‘applied’ enterprise computing: has identified it’s utility has (roughly) identified the underlying issue - change is devising its own theory-lite solutions ‘pure’ ontology: also has theories about: underlying issue – change the relation between immutability and change suggest that these can usefully be joined up utility and theory pull in the same direction show how philosophical immutability provides a theory that can: deep our understanding of enterprise computing immutability lead to better enterprise computing systems “There is nothing so practical as a good theory” Kurt Lewin (p Field theory in social science ) corollary: not having a good theory may be much less practical 7

8 big data: immutability what is immutability? in enterprise computing why does big data like it? 8

9 © 2012 BORO Solutions what is immutability? in enterprise computing “In programming, an immutable object is an object whose state cannot be modified after it is created.” Person Age Person Date of birth looks mutable looks immutable Brad Pitt Brad Pitt 48 Brad Pitt Brad Pitt

10 © 2012 BORO Solutions recognised pragmatic technical benefits view from the sharp end: “Benefits of immutability Immutable classes, when used properly, can greatly simplify programming. They can only be in one state, so as long as they are properly constructed, they can never get into an inconsistent state. You can freely share and cache references to immutable objects without having to copy or clone them; you can cache their fields or the results of their methods without worrying about the values becoming stale or inconsistent with the rest of the object's state. Immutable classes generally make the best map keys. And they are inherently thread-safe, so you don't have to synchronize access to them across threads.” “Freedom to cache Because there is no danger of immutable objects changing their value, you can freely cache references to them and be confident that the reference will refer to the same value later. Similarly, because their properties cannot change, you can cache their fields and the results of their methods.” some references: Adrian Birka and Michael D. Ernst. A practical type system and language for reference immutability. In John M. Vlissides and Douglas C. Schmidt, editors, OOPSLA, pages 35–49. ACM, Christian Haack, Erik Poll, Jan Schafer, and Aleksy Schubert. Immutable objects for a java-like language. In ESOP, pages 347–362, Richard Bornat, Cristiano Calcagno, Peter W. O’Hearn, and Matthew J. Parkinson. Permission accounting in separation logic. In POPL, pages 259–270, M. J. Parkinson. Local Reasoning for Java. PhD thesis, Computer Laboratory, University of Cambridge, UCAMCL-TR-654. NOTE: no mention of ontological theories of change! 10

11 © 2012 BORO Solutions Replica 1 Replica 2 why does big data like immutability? number of potential advantages; focus on one: big data brings performance challenges replication has performance advantages e.g. put a copy of the data closer to the user. immutability makes replication simpler if the data is immutable, then one can only create and read the entries on the database. so keeping replicas up to data can focus on appending data called ‘append-only’ - a kind of ‘storage monotonicity’ »no implication of entailment monotonicity 11

12 © 2012 BORO Solutions accountants don't use erasers accountants don't use erasers because they don’t want to end up in jail when an entry is made in the accounting records, it is never erased can add another entry to correct a mistake, but cannot erase the original entry append-only (data storage monotonicity) has been around for a long time! was centuries old when described in: Fra Luca Bartolomeo de Pacioli, Summa de arithmetica, geometria, proportioni et proportionalità (Venice 1494) 12

13 © 2012 BORO Solutions an enterprise computing example: problem Datomic a new development in databases - their view of the problem “So the data model in Datomic is a very atomic model, we store entity, attributes and values and if you're trying to make things immutable and you want to keep track of time, then you move away from what I would call place-oriented programming which is what you do when you have tables or documents. There is a place for this fact to go. Instead you say "I want to keep track of all the facts ever", and when you do that, you need to be able to say "A lot of things aren’t facts", that is why we want to change our databases, because somebody moves and has a new address. So the way to do that without using places and going and replacing the address, is to say "This was Fred’s address at this point of time" and later you say "This is Fred’s address at that point of time".” summary: things in the domain change 13

14 © 2012 BORO Solutions an enterprise computing example: solution Datomic (technical) solution “Both are facts, one was true for the interval between the two, and one was true since that. So each fact then is atomic in being an entity, attribute, value and time, and we call that a "datum", and the time we actually encode by remembering the transaction you were part of, because transactions are serialized, your transaction designates when you happened relative to everything else. That way we can encode the time of day on the transaction. Transactions are entities like any others, so you can encode other facts about the transaction, for instance, who enacted it, or what was the providence of the data that came in. In this way you can, for instance, very easily find out what else was said when this was said, find the other things said in the same transaction. So that adds the time element to the data, and it allows you to keep all the data.” summary: theory-lite technical solution transaction-stamp and append-only underneath the covers is a monotonic ordering by transaction can map this back to what Bertrand Russell called an “at-at” approach at this time it was x, at that time it was y The Principles of Mathematics (1903) 14

15 © 2012 BORO Solutions what is happening? change happens (exists) in the domain the computing system needs to represent this changing the representation directly is costly find technical (theory-lite) ways to avoid representing the change with a change in representation understandably a ‘Plato’s Cave’ mentality has been adopted that focuses on the representation rather than the represented world-to-system fit shift the focus to the world what is the nature of change

16 ontology architecture build engineered rather than accidental ontologies ontology for change is a vital component 16

17 © 2012 BORO Solutions why ontological architecture? building a large scale system without some kind of organisation guarantees a disaster building an ontology for a large scale system without some kind of organisation guarantees a disaster a key aspect of ontology organisation is ontology architecture an ontological architecture needs some organising principles sensible to make these explicit sensible to consciously and rationally decide on these principles some references for ontological architecture: Partridge, C. (1996). Business Objects: Re - Engineering for re - use. Oxford, Butterworth Heinemann. Partridge, C. (2002). LADSEB-CNR - Technical report 06/02 - Note: A Couple of Meta-Ontological Choices for Ontological Architectures. Padova, LADSEB CNR, Italy Recap of (2002) paper above. Borgo, S., A. Gangemi, N. Guarino, C. Masolo, and A. Oltramari. (2002). “WonderWeb Deliverable D15 Ontology RoadMap.” The WonderWeb Library of Foundational Ontologies and the DOLCE ontology. p ROADMAP OF MAJOR ONTOLOGICAL CHOICES Salim K. Semy, Mary K. Pulvermacher, Leo J. Obrst. (2004). Toward the Use of an Upper Ontology for U.S. Government and U.S. Military Domains: An Evaluation. DOCUMENT NUMBER MTR 04B , MITRE TECHNICAL REPORT p Table 2. Ontological Choices Summary. 17

18 © 2012 BORO Solutions change ontology for change is a vital component some of these principles are based upon metaphysical choices major metaphysical choices include: perdurantism versus endurantism presentism versus eternalism absolute versus relative space, time and space-time modally extended versus unextended individuals materialism and non-materialism extensionalism versus non-extensionalism – I – universals extensionalism versus non-extensionalism – II – particulars topology of time – branching or linear principles (metaphysical choices) ≈ components 18

19 change architecture component engineering an architecture for change: a major aspect 19

20 © 2012 BORO Solutions some basic issues are old around 500 B. C. Heraclitus put forward one view: “Everything flows and nothing abides; everything gives way and nothing stays fixed. You cannot step twice into the same river, for other waters and yet others, go flowing on. Time is a child, moving counters in a game; the royal power is a child's.” transience is basic, the present is primary. a generation or so later Parmenides put forward the opposing view: “There remains, then, but one word by which to express the [true] road: Is. And on this road there are many signs that What Is has no beginning and never will be destroyed: it is whole, still, and without end. It neither was nor will be, it simply is—now, altogether, one, continuous…” permanence is basic. time is at best secondary, at worst illusory translation (for both): Wheelwright, Philip The Presocratics. Indianapolis. 20

21 © 2012 BORO Solutions enormous literature in philosophy still an active research area: Adams, Robert M., “Time and Thisness,” in French, Peter, Uehling, Theodore, and Wettstein, Howard (eds.), Midwest Studies in Philosophy 11, Studies in Essentialism (University of Minnesota Press, 1986), pp Bigelow, John, “Presentism and Properties,” in Tomberlin, James (ed.), Philosophical Perspectives 10, Metaphysics (Blackwell, 1996), pp Alexander, H.G. (ed. and trans.), The Leibniz-Clarke Correspondence (Manchester University Press, 1956). Aristotle, De Interpretatione, in Aristotle, The Complete Works of Aristotle (Princeton University Press, 1984). Aristotle, Physics, in Aristotle, The Complete Works of Aristotle (Princeton University Press, 1984). Bourne, Craig, A Future for Presentism (Oxford University Press, 2006). Bradley, F.H., Appearance and Reality (Swan Sonnenschein, 1893; second edition, with an appendix, Swan Sonnenschein, 1897; ninth impression, corrected, Clarendon Press, 1930). Haslanger, Sally, “Endurance and Temporary Intrinsics,” Analysis 49 (1989), pp Haslanger, Sally, “Humean Supervenience and Enduring Things,” Australasian Journal of Philosophy 72 (1994), pp Haslanger, Sally, “Persistence, Change, and Explanation,” Philosophical Studies 56 (1989), pp Hawley, Katherine, How Things Persist (Oxford University Press, 2001). Heller, Mark, The Ontology of Physical Objects: Four Dimensional Hunks of Matter (Cambridge University Press, 1990). Hinchliff, Mark, “The Puzzle of Change,” in Tomberlin, James (ed.), Philosophical Perspectives 10, Metaphysics (Blackwell, 1996), pp Kant, Immanuel, The Critique of Pure Reason, translated by Norman Kemp Smith (Macmillan, 1963). Keller, Simon, and Nelson, Michael, “Presentists Should Believe in Time-Travel,” Australasian Journal of Philosophy 79 (2001), pp Le Poidevin, Robin (ed.), Questions of Time and Tense (Oxford University Press, 1998). Le Poidevin, Robin, and McBeath, Murray (eds.), The Philosophy of Time (Oxford University Press, 1993). Lewis, David, On the Plurality of Worlds (Basil Blackwell, 1986). Markosian, Ned, “A Defense of Presentism,” in Zimmerman, Dean (ed.), Oxford Studies in Metaphysics, Vol. 1 (Oxford University Press, 2003). Markosian, Ned, “How Fast Does Time Pass?,” Philosophy and Phenomenological Research 53(1993), pp Markosian, Ned, “The Open Past,” Philosophical Studies 79 (1995), pp Maudlin, Tim, The Metaphysics Within Physics (Oxford University Press, 2007). Maxwell, Nicholas, “Are Probabilism and Special Relativity Incompatible?,” Philosophy of Science 52 (1985), pp McCall, Storrs, A Model of the Universe (Clarendon Press, 1994). McTaggart J., The Unreality of Time Mind 17.68: 457–474. Meiland, Jack W., “A Two-Dimensional Passage Model of Time for Time Travel,” Philosophical Studies 26 (1974), pp Mellor, D.H., Real Time II (Routledge, 1998). Newton-Smith, W.H., The Structure of Time (Routledge & Kegan Paul, 1980). Price, Huw, “A Neglected Route to Realism About Quantum Mechanics,” Mind 103 (1994), pp Price, Huw, Time's Arrow and Archimedes' Point: New Directions for the Physics of Time (Oxford University Press, 1996). Prior, Arthur N., “Changes in Events and Changes in Things,” in Prior, Arthur, Papers on Time and Tense (Oxford University Press, 1968), pp Prior, Arthur N., “The Notion of the Present,” Stadium Generale 23 (1970), pp Prior, Arthur N., Papers on Time and Tense (Oxford University Press, 1968). Prior, Arthur N., Past, Present, and Future (Oxford University Press, 1967). Prior, Arthur N., “Some Free Thinking About Time,” in Copeland, Jack, (ed.) Logic and Reality: Essays on the Legacy of Arthur Prior (Clarendon Press, 1996), pp Prior, Arthur N., “Thank Goodness That's Over,” in Prior, Arthur N., Papers in Logic and Ethics (Duckworth, 1976), pp Putnam, Hilary, “Time and Physical Geometry,” Journal of Philosophy 64 (1967), pp Quine, W.V.O., Word and Object (MIT Press, 1960). Rea, Michael C., “Temporal Parts Unmotivated,” The Philosophical Review 107 (1998), pp Savitt, Steven, “There's No Time Like the Present (in Minkowski Spacetime),” Philosophy of Science 67 (2000), supplementary volume, Proceedings of the 1998 Biennial Meetings of the Philosophy of Science Association, pp Savitt, Steven (ed.), Time's Arrows Today: Recent Physical and Philosophical Work on the Direction of Time (Cambridge University Press, 1995). Shoemaker, Sidney, “Time Without Change,” Journal of Philosophy 66 (1969), pp Sider, Ted, Four-Dimensionalism: An Ontology of Persistence and Time (Oxford University Press, 2001). Sider, Ted, “Presentism and Ontological Commitment,” Journal of Philosophy 96 (1999), pp Sklar, Lawrence, Space, Time, and Spacetime (University of California Press, 1974). Smart, J.J.C., Philosophy and Scientific Realism (Routledge & Kegan Paul, 1963). Smart, J.J.C., “The River of Time,” Mind 58 (1949), pp (reprinted in Flew, Antony (ed.), Essays in Conceptual Analysis (St. Martin's Press, 1966), pp ). Smart, J.J.C., “Spatialising Time,” Mind 64 (1955), pp Smith, Quentin, Language and Time (Oxford University Press, 1993). Stein, Howard, “On Einstein-Minkowski Space-Time,” Journal of Philosophy 65 (1968), pp Stein, Howard, “A Note on Time and Relativity Theory,” Journal of Philosophy 67 (1970), pp Swinburne, Richard, “The Beginning of the Universe,” Proceedings of the Aristotelian Society, Supplementary Volume 50 (1966), pp Swinburne, Richard, Space and Time (Macmillan, 1968). Taylor, Richard, Metaphysics, 4th Edition (Prentice-Hall, 1992). Thomson, Judith Jarvis, “Parthood and Identity Across Time,” Journal of Philosophy 80 (1983), pp Thorne, Kip S., Black Holes and Time Warps (Norton, 1994). Tooley, Time, Tense, and Causation (Oxford: Oxford University Press, 1997). Van Inwagen, Peter, An Essay on Free Will (Clarendon Press, 1983). Van Inwagen, Peter, “Four-Dimensional Objects,” Nous 24 (1990), pp Weingard, Robert, “Relativity and the Reality of Past and Future Events,” British Journal for the Philosophy of Science 23 (1972), pp Williams, Donald C., “The Myth of Passage,” Journal of Philosophy 48 (1951), pp Yourgrau, Palle, Gödel Meets Einstein: Time Travel in the Göodel Universe (Open Court, 1999). Zimmerman, Dean, “The A-theory of Time, the B-theory of Time, and 'Taking Tense Seriously',” Dialectica 59 (2005), pp Zimmerman, Dean, “Persistence and Presentism,” Philosophical Papers 25 (1996), pp Zimmerman, Dean, “Temporary Intrinsics and Presentism,” in van Inwagen, Peter, and Zimmerman, Dean (eds.), Metaphysics: The Big Questions (Blackwell, 1998), pp Zwart, P.J., About Time (North-Holland Publishing Co., 1976). 21 McTaggart J., The Unreality of Time Mind 17.68: 457– 474.

22 © 2012 BORO Solutions aside: also a research topic in computer science some references: Zamborlini, V., Guizzardi, G.. On the Representation of Temporally Changing Information in OWL. In Enterprise Distributed Object Computing Conference Workshops (EDOCW), th IEEE International, Oct. 2010, pp H. U. Krieger, “Where Temporal Description Logics Fail: Representing Temporally-Changing Relationships,” In: A. Dengel, K. Berns, T.M. Breuel, F. Bomarius, T.R. Roth- Berghofer (eds.): KI 2008: Advances in Artificial Intelligence, Lecture Notes in Artificial Intelligence number 5243, Pages , Kaiserslautern, Springer, Berlin (2008) H. U. Krieger, B. Kiefer and T. Declerck, “A framework for temporal representation and reasoning in business intelligence applications,” In: AAAI 2008 Spring Symposium on AI Meets Business Rules and Process Management. (2008) 59–70 22

23 © 2012 BORO Solutions McTaggart’s A-Series and B-Series McTaggart J., The Unreality of Time Mind 17.68: 457–474. distinguishes two ways of ordering events in time: a relation of ‘earlier than’ this ordering McTaggart calls the B-series a selection of a privileged moment within the B-series as the present moment. this ordering McTaggart calls the A-series NOTE: different formal structures B-series has no privileged moment, all moments are equal A-series has a privileged moment – ‘now’ = present these lead to different relations and properties: A-properties: present, past, future, 5 years hence, 5 years ago B-relations: earlier than, later than, simultaneous with, 5 years later than we have seen something similar earlier: recall person ‘age’ an A-property and ‘date-of-birth’ a B-moment 23

24 © 2012 BORO Solutions two opposing theses this gives us two opposing theses about the nature of change reality of time thesis: an event changes by first being future, then present, and then past, in other words, by changing positions relative to ‘now’ in an A-series ordering unreality of time thesis: events do not change argument time is real only if real change occurs if there are no changes, then there is no time - time is unreal if there are changes, then there is time - time is real which thesis to select? if time is unreal, things are immutableif time is unreal, things are immutable enterprise computing utility prefers the unreality of time thesis enterprise computing utility prefers the unreality of time thesis 24

25 © 2012 BORO Solutions explaining talk about unreal change if one adopts the ‘unreality of time’ thesis, then change does not exist adopting the thesis is a revisionary stance, so needs more explanation one needs to have a story about our everyday talk about change two similar ‘stories’: redefining change - “Cambridge” change an entity x has changed where there is some predicate F that is true of x at a time t 1 but not true of x at some other time t 2. Geach, P.T. (1969). God and the Soul, p – named it in homage to McTaggart and Russell who were from Cambridge (see Russell’s at-at theory of motion - at this time it was x, at that time it was y – The Principles of Mathematics (1903)) redefining talk - change fictionalism fictionalism is where talk about a thing is useful, but does not commit one to its existence metaphorical talk is a common example we can tie ourselves in unnecessary knots by insisting that ordinary ways of talking about a thing (such as changes) are always to be taken literally. an old example of Wittgenstein’s; if someone says they “married money,” we do ourselves no favours by hunting around for the money they married 25

26 © 2012 BORO Solutions unreality of time ontology: example situation there is a car. it has a front right tyre. when the car was built, a tyre was ‘installed’ in the front right side of the car. at some point in time, this tyre was taken off and a new tyre installed. useful to count the objects … (hopefully this is not contentious) #20 – car (system). #25 – car’s front right tyre (system component). #21 – original tyre. #22 – replacement tyre. obvious intuitive puzzle seem to be more objects than you see when you look at the car what is the connection between the system component tyres and the ‘manufactured’ tyres? 26

27 © 2012 BORO Solutions visualising the objects 27 System Component all the objects are ‘immutable’ – there is no change

28 © 2012 BORO Solutions this pattern is commonplace 28 another example

29 © 2012 BORO Solutions ‘immutable’ meets ‘unreality of time’ clearly there is a close match between: the aspirations of ‘immutable’, and the nature of the ‘unreality of time’ if a system’s ontological architecture’s change component is based upon the ‘unreality of time’, then: implementing immutability is a natural and straight- forward the objects in an ‘unreality of time’ ontology do not change so no need to represent change in the domain NOTE: no up-front need for time-stamping time-stamping properties often a sign of the ‘reality of time’ thesis 29

30 © 2012 BORO Solutions a match made in heaven? ‘pure’ ontology and ‘applied’ enterprise computing pull in the same direction pure ontology provides a thesis that explains why things are immutable – and what they look like (in enterprise computing speak; how to model them) enterprise computing provide a pragmatic reason for selecting the ‘unreality of time’ thesis BUT … 30

31 not the whole story need to consider epistemology 31

32 © 2012 BORO Solutions some obvious incompatible cases what happens if: a user makes a mistake that needs to be changed ‘Partridge’ is input as ‘Patridge’ (often happens to me) the original input needs to be retracted and the correct input made the system makes a best estimate on partial information that gets updated in the light of new information given what it knows now, my bank balance is £150 I then tell it about a purchase for £50 on Amazon it needs to update my bank balance various types of issue: mistaken (false?) knowledge incomplete knowledge all issues about what the system knows AKA epistemic issues

33 © 2012 BORO Solutions incomplete knowledge: workaround engineering solution event sourcing: a ‘pattern’ used in enterprise computing: “Capture all changes to an application state as a sequence of events. We can query an application's state to find out the current state of the world, and this answers many questions. However there are times when we don't just want to see where we are, we also want to know how we got there. Event Sourcing ensures that all changes to application state are stored as a sequence of events. Not just can we query these events, we can also use the event log to reconstruct past states, and as a foundation to automatically adjust the state to cope with retroactive changes.” incomplete knowledge is calculated not stored incomplete knowledge is ephemeral not persisted ingenious solution two-tier knowledge 33

34 two-dimensional semantics 34

35 © 2012 BORO Solutions well-known ‘feature’ well-known ‘feature’ in both philosophy (and enterprise computing) two-dimensional semantics in philosophy arises in various guises, most recently called ‘two-dimensional semantics’ Extensive literature going back quite a few decades (includes); Evans, G., Reference and contingency. The Monist 62: Stalnaker, R., Assertion. In (P. Cole, ed.) Syntax and Semantics: Pragmatics, Vol. 9. New York: Academic Press Kaplan, D., Dthat. In (P. Cole, ed.) Syntax and Semantics. New York: Academic Press Davies, M. & Humberstone, I.L., Two notions of necessity. Philosophical Studies 58: Kaplan, D., Demonstratives. In (J. Almog, J. Perry, and H. Wettstein, eds.) Themes from Kaplan. Oxford: Oxford University Press Chalmers, D.J., The Conscious Mind: In Search of a Fundamental Theory. Oxford: Oxford University Press Jackson F., From Metaphysics to Ethics: A Defense of Conceptual Analysis. Oxford: Oxford University Press Chalmers, D.J., On sense and intension. [consc.net/papers/intension.html] Chalmers, D.J., Epistemic two-dimensional semantics, Philosophical Studies 118:

36 © 2012 BORO Solutions epistemic dimension: an example 36 I say today You say today I said yesterday You said yesterday “I am hungry” “Chris is hungry on 24th July" indexicals are good example of how the epistemic dimension works (see Kaplan 1979, 1989) indexed to a person and a time and a (possible) world, if you have a possible world semantics sometimes known as ‘centred worlds’; a triple of a world, an individual and a time, or a time-slice of an individual

37 bitemporal data enterprise computing’s version of two dimensional semantics

38 © 2012 BORO Solutions bitemporal data A temporal database with built-in time aspects the temporal aspects usually include; valid time denotes the time period during which a fact is true with respect to the real world transaction time is the time period during which a fact is stored in the database bitemporal data combines both valid and transaction time same data will often have different times consider a temporal database storing data about the 18th century the valid time of these facts is somewhere between 1701 and 1800 whereas the transaction time starts when we insert the facts into the database, for example, January 21, 1998 being incorporated into the SQL standard 38

39 © 2012 BORO Solutions two-dimensional data reasonably direct translation; valid time = ontic dimension transaction time = epistemic dimension illustrates how the same issues can arise in philosophy and enterprise computing and similarly structured solutions same separation of concerns 39

40 architecture for epistemic change which way to go?

41 © 2012 BORO Solutions reality or unreality of time? again epistemic architecture change component options: reality or unreality of time? again system’s knowledge does change over time what it knew yesterday could be different from what it knows today could be different from what it will know tomorrow remember centred worlds – time-slice of the system seems like ‘reality of time’ is the natural way to go ‘reality’ as a relation between a momentary state of the individual (system) and what it knows what = ontology it knows = epistemology 41

42 © 2012 BORO Solutions implementing the epistemic architecture requirement immutability is a ‘good thing’ how to implement it over the epistemic A series structure? solution the theoretical part treat the epistemology as a view over an ontology, so it inherits its immutability so layers rather than dimensions separate what is known from the knowing event bitemporal data works in this way the engineering part order (time-stamp as well, if you want) and append increases in knowledge treat retractions as separate transactions 42

43 summary

44 © 2012 BORO Solutions summary there is an opportunity to join up pure ontology and applied enterprise computing both have seen a challenge in in change a solution in immutability enterprise computing has recognised the practical benefits of immutability but has no real theory to guide its modelling philosophical ontology has a number of theories of change one of these is based upon immutability (unreality of time) theory looks like a match made in heaven can lead to: better understanding better models and so systems situation is more complex epistemic as well as ontological factors need to be considered a two-dimensional (or two-layered) approach preserves the ontological benefits 44

45 questions?


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