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1 Handle the complexity Five mechanisms to understand and handle our complex world: classification generalization aggregation composition and power types.

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Presentation on theme: "1 Handle the complexity Five mechanisms to understand and handle our complex world: classification generalization aggregation composition and power types."— Presentation transcript:

1 1 Handle the complexity Five mechanisms to understand and handle our complex world: classification generalization aggregation composition and power types.

2 2 Classification Concepts Term Referent ”Nisse Hall” ”Anna Svan” ”Nisse Hall” ”Anna Svan” ”Student” When we classificate we apply a concept (in form of an object type) to object. It means that we only visualize the properties which are common to see similarities. Without this concepts (object types) we would only know that things are different. ”Anna Svan” ”Nisse Hall” ”Student”

3 3 Classification Object typeObject ?..* 0..* Classify is_an_instance_of Anna Svan Student Woman Nils Hall Cecilia Björk Zlatan

4 4 Classification Object type Object (?)..* 0..* classify is_an_instance_of 1..* 0..* classify is_an_instance_of Object type and class are almost the same thing? The reality Models Class Object

5 5 Classification Anna Svan Nisse Hall Cecilia Björk Zlatan Student Man Woman

6 6 Classification The objects does not group themselves. The objects form groups thanks to the concepts (in form of object types) that we apply or place at the objects. It is people that group/classify. Note how children immediately see the difference between a dog and a cat. They seem to be able to understand the difference between the concept (the object type) dog and the concept (the object type) cat.

7 7 Generalization Concepts Term Referent ”Nisse Hall” ”Anna Svan” ”Nisse Hall” ”Anna Svan” ”Student” ”Cecilia Björk” ”Person” ”Woman” Generalization means that concepts, i.e object types that entirely includes or comprise other object types are distinguished When we are generalizing we show if object types – not objects - have something in common. ”Anna Svan” ”Nisse Hall” ”Student” ”Person” ”Kvinna

8 8 Generalization Concepts ”Nisse Hall” ”Anna Svan” ”Student” ”Cecilia Björk” ”Person” ”Woman” Person Student Woman The reality Models

9 9 Generalization - notation Anna Svan Nisse Hall Cecilia Björk Zlatan Student Woman Person Woman Student

10 10 Generalization set Anna Svan Cecilia Björk Student Woman Person Nils Hall Zlatan Man Person ManWoman Student

11 11 Generalization Person Nils Hall Cecilia Björk Anna Svan Eva Strid Zlatan Man Woman Person Man Woman

12 12 Generalization – inheritance Eva Strid Anna Svan Nils Hall Cecilia Björk Zlatan Person Student personalnr studentregnr Superclass of Student Subclass of Person

13 13 More examples of generalization Person Student personalnr studentregnr Teacher emplyeenr eva strid:Student personalnr = ” XXXX” studentregnr = ” ” eva strid:Teacher personalnr = ” XXXX” employeenr = ”177745” Eva Strid Cecilia Björk Nils Hall Anna Svan Arne Stolt Person Student Lärare arne stolt:Teacher personalnr = ” XXXX” employeenr = ”177750” Zlatan

14 14 Classification och generalization Generalization: Object type is_a_subclass_to 0..* is_a_superclass_to Classification: Object typeObject 1..* 0..* classify is_an_instance_of

15 15 Classification or generalization? 2. A Border Collie is a dog. 3. Dogs are animals. 4. A Border Collie is a breed of dog. 5. Dog is a sort. Test if following is a classification or a generalization! 1. Shep is a Border Collie.

16 16 The reality and models – again The realityGraphical models/diagram Nils Hall Cecilia Björk Anna Svan Eva Strid Zlatan Nils Hall Cecilia Björk Anna Svan Eva Strid Zlatan Person ManWoman zlatan:Man nilsHall:Man annaSvan:Kvinna ceciliaBjörk:Kvinna evaStrid:Kvinna Classification Woman Man Person Generalization Classification

17 17 Aggregation och composition Rabbit EarLeg Order Order line 0..* 1 AggregationComposition

18 18 Composition Object is composed of 0..* is part of Composition: Classification: Object typeObject 1..* 0..* classify is_an_instance_of Generalization: Object type is_a_subclass_to 0..* is_a_superclass_to

19 19 Abstraction Composition, aggregation, generalization and classification can be looked at as different types of abstraction. Note that some authors think that only the classiffication is abstraction. There are also authors who thinks that neither composition, aggregation, generalization nor classification are abstractions but to abstract is to start from the reality and to create models.

20 20 Why Power Type? Dog name weight breed average_weight maw_strength (for german shepherds) back_length (for dachshunds)

21 21 Why Power Type? Dog name weight breed average_weight German shepherdDachshund maw_strength back_length

22 22 Why Power Type? Dog name weight German shepherdDachshund maw_strengthback_length Breed * breed_name average_weight

23 23 Why Power Type? Dog name weight German shepherdDachshund maw_strength back_length Breed * breed_name average_weight Criteria * criterion_name Dogshow 1..* Show_name responsible hall 0..*


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