61

Model No.				61
Short Citation				(Loucopoulos et al. 1991)
Year				1991
Special Name				ERT (ER-Time)
Descendant of
Constructs	Inherent	Entity Type		r: class, sg: time period class, complex object, derived
		Relationship Type		sg: generalization/specialization, derived, sg/l: cardinality
		Value Sets / Attributes		sg/l: complex, role
	New	Invented	Adapted
			Included
		Borrowed	Included
			Added
Syntactic Rules				X
Semantics				formalized
Focus				g/t
Data Definition				l
Data Manipulation				l
Remarks
Cause	Citation			... capturing and representation of business rules (p. 323). ... the need for expressiveness power of conceptual modelling formalisms... (p. 324).
	Content	Expressiveness		integrity
		Applicability
		Correction
		Integration
		Implementation
		Other
Alternative Publications				(Theodoulidis et al. 1991), (Theodoulidis et al. 1992)
Binary Vector	Structure/General	[E1]		1
		[E2]		1
		[E3]		i
		[E4]		1
		[E5]
		[E6]
	Structure/Integrity	[E7]
		[E8]
		[E9]		i
		[E10]		1
		[E11]		1
		[E12]		1
		[E13]		i
		[E14]		i
		[E15]		f
		[E16]		f
	Behavior	[E17]
		[E18]
	Application	[E19]
		[E20]
		[E21]
		[E22]
		[E23]
		[E24]
		[E25]
		[E26]
		[E27]
	Domain-Specifics	[E28]
		[E29]
		[E30]
		[E31]
		[E32]
		[E33]
Expressiveness Values	Total			0.36
	Data Model			0.67
	Application			0.00
	Domain Specifics			0.00
Partially Redundant Constructs	Conjunctive Concepts			S, J, T
	Linked Concepts			D

C: composite attributes/objects, D: derived entity types, F: uncertain attributes, H: dependency/ total relationship, O: optional attributes, OR: order relation, R: anker, X: non-transferable relationship

S: specialization/general, J: specialization (disjoint/overlapping), T: specialization (total/partial), W: weak entity types, Z: time attributes (multivalued)

RD: Literals [E28] to [E33]

RD: Literals [E19] to [E27]

RD: Literals [E1] to [E18]

RD: Literals [E1] to [E33]

perceptual(!a)

The attributes (e.g., shape, color) differ through perceptual aspects, in contrast to attributes differing in their symbolic labels (e. g., book titles).

agent_r(!r)

The relationship type represents involvements of agents, e.g., receive/send messages, do actions.

agent_e(!e)

The entity type represents an agent that can, e.g., perform actions, communicate and make commitments.

conceptual(!e)

Entities of a conceptual entity type (e.g., a plot of a book) represent only information.

search(!e)

Some entity type represents a class of items that share time and memory requirements when searched (e. g., pile, chain, stored list).

geoscientific(!e)

Some entity type represents a special class of geo-scientific objects (e.g., geo-objects, map objects).

time_dependent(!a)

During schema evolution, the name, the domain or the existence (addition/deletion) of some attribute may change.

time_participate(!e, !r)

The allowed or required participation of entities in relationships depends on the time horizon considered.

causal_relation(!e1, !e2, !r)

a_fuzzy(!a, !rn)

Some attribute is not with certainty but with some grade !rn member of a schema.

r_fuzzy(!r, !rn)

Some relationship type is not with certainty but with some grade !rn member of a schema.

e_fuzzy(!e, !rn)

An entity plays a certain role in a relationship.

classification(!e1, !e2, !r)

The (binary) relationship type relates instances of entity type !e1 (e.g., ’city’) to instances of the more aggregated entity type !e2 (e.g., ’country’).

dimensional_level(!e)

Some entity type represents a special class of geo-scientific objects (e.g., geo-objects, map objects).

fact(!r)

The relationship type represents a subject of multidimensional data analysis.

r_transaction(!r)

All instances of an entity type participate in one instance of the relationship type.

e_transaction(!e)

All instances of an entity type must participate more than one time in the formation of instances of an relationship type.

r_ex_constraint(!r)

General restrictions are defined on the relationship type that must hold for all of its instances and in any database state.

e_ex_constraint(!e)

General restrictions are defined on the entity type that must hold for all of its instances and in any database state.

ident_participate(!e1, !e2, !r)

The entities of distinct types that are associated by some relationship are identical.

excl_participate(!e, !r1,... !rj)

Entities of some type are involved in only one of several types of relationships.

option_participate(!e, !r)

Some entities of a given type are not involved in instances of some relationship type.

min_participate(!e1, ..., ei, !r, N)

All entities of some type(s) must participate in at least one instance of a relationship type.

max_participate(!e1,..., !ei, !r, N)

All entities of some type(s) participate in more than one instance of a relationship type.

value_description(!a)

The allowed attribute values are specified, e.g., by listing them (including NULL or UNDEFINED), by providing data types or by stating ranges. This also covers composite attributes.

multivalued(!a)

The attribute has more than one value for some entity or relationship.

key_description(!e)

The primary key of the entity type is described.

r_condition(!r)

An arbitrary condition is defined on a relationship type to divide its instances into subsets.

e_condition(!e)

An arbitrary condition is defined on an entity type to select some of its instances in a given database state.

derived_rel(!r)

A relationship is not stored but derived from existing relationships, respectively; derivation follows a derivation rule.

derived_att(!a)

An attribute and its values are not stored but derived from the values of other attributes; derivation follows a derivation rule.

role(!e, !r)

An entity plays a certain role in a relationship.

e_type_treatment(!r, !e)

Some relationship type is treated as an entity type. This is also called aggregation.

1: expressed according to focus, f: focus shift, a: assumption, i: implied by another proposition, m: missing statement (implied by descent)

publications that are equal in content

e: explanations and examples, l: dedicated language

g: graphical notation, t: textual notation

X: original rules not changed

d: deleted, l: label, r: renamed, rf: refer to, sg: general specialization, sd: domain-specific specialization, X: semantics and name of the original construct not changed

d: deleted, l: label, r: renamed, rf: refer to, sg: general specialization, sd: domain-specific specialization, X: semantics and name of the original construct not changed, mapping: 1:N- and M:N-types of relationships, min/max: relationship types, characterized by min/max-cardinalitied

d: deleted, l: label, r: renamed, rf: refer to, sg: general specialization, sd: domain-specific specialization, X: semantics and name of the original construct not changed

if stated by the author

ER model mentioned for the first time (according to the year of the conference, references or information by the author); may differ from the year of the evaluated publication

Publication used for evaluation