Support for virtual states and deltas between them is useful for a variety of database applications, including hypothetical database access, version management, simulation, and active databases. The Heraclitus paradigm elevates delta values to be "first-class citizens" in database programming languages, so that they can be explicitly created, accessed and manipulated.A fundamental issue concerns the trade-off between the "accuracy" or "robustness" of a form of delta representation, and the ease of access and manipulation of that form. At one end of the spectrum, code-blocks could be used to represent delta values, resulting in a more accurate capture of the intended meaning of a proposed update, at the cost of more expensive access and manipulation. In the context of object-oriented databases, another point on the spectrum is "attribute-granularity" deltas which store the net changes to each modified attribute value of modified objects.This paper introduces a comprehensive framework for specifying a broad array of forms for representing deltas for complex value types (tuple, set, bag, list, o-set and dictionary). In general, the granularity of such deltas can be arbitrarily deep within the complex value structure. Applications of this framework in connection with hypothetical access to, and "merging" of, proposed updates are discussed.

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	AHV95	Serge Abiteboul , Richard Hull , Victor Vianu, Foundations of Databases: The Logical Level, Addison-Wesley Longman Publishing Co., Inc., Boston, MA, 1995
	BDD+95	O. Boucelma, J. Dalrymple, M. Doherty, J. C. Franchitti, R. Hull, R. King, and G. Zhou. Incorporating Active and Multi-database-state Services into an OSA- Compliant InteroperM)ility Framework. In The Collected Arcad,,a P~~pers, Second Ed,,tion. University of California, Irvine, May 1995.
	Cat93	Roderick G. Cattell , Tom Atwood, Object Database Standard: ODMG-93, Morgan Kaufmann Publishers Inc., San Francisco, CA, 1993
	DDD+96	M. Derr, J. Durand, M. Doherty, R. Hull, and M. Rupawalla. Applications of Heraclitus in telecommunications information processing. Technical report, University of Colorado, Boulder, 1996.
	DH95	Michael Doherty , Richard Hull, Towards a Framework for Efficient Management of Potentially Conflicting Database Updates, Proceedings of the Sixth IFIP TC-2 Working Conference on Data Semantics: Database Applications Semantics, p.317-344, May 30-June 02, 1995
	DHDD95	Michael Doherty , Richard Hull , Marcia A. Derr , Jacques Durand, On Detecting Conflict Between Proposed Updates, Proceedings of the Fifth International Workshop on Database Programming Languages, p.7, September 06-08, 1995
	DHR96	M. Doherty, R. Hull, and M. Rupawalla. A framework for manipulating proposed updates in objectoriented data.bases, 1996. Technical report in preparation.
	GHJ+93	Shahram Ghandeharizadeh , Richard Hull , Dean Jacobs , Jaime Castillo , Martha Escobar-Molano , Shih-Hui Lu , Junhui Luo , Chiu Tsang , Gang Zhou, On Implementing a Language for Specifying Active Database Execution Models, Proceedings of the 19th International Conference on Very Large Data Bases, p.441-454, August 24-27, 1993
	GHJ96	Shahram Ghandeharizadeh , Richard Hull , Dean Jacobs, Heraclitus: elevating deltas to be first-class citizens in a database programming language, ACM Transactions on Database Systems (TODS), v.21 n.3, p.370-426, Sept. 1996  [doi>10.1145/232753.232801]
	HJ91	Richard Hull , Dean Jacobs, Language Constructs for Programming Active Databases, Proceedings of the 17th International Conference on Very Large Data Bases, p.455-467, September 03-06, 1991
	JH91	Dean Jacobs , Richard Hull, Database programming with delayed updates, Proceedings of the third international workshop on Database programming languages : bulk types & persistent data: bulk types & persistent data, p.416-428, April 1992, Nafplion, Greece

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