Inheritance hierarchy

Figure 3 One way to define a multiple-inheritance hierarchy for bonds...

Features and functions of our system are encapsulated into packages called objects. Each object has a known relationship with other objects in the system. Objects may belong to a multiple-inheritance hierarchy and can be connected through relationships (an object can be stored as the value of an attribute of another object). 

I ask 3 Transform ( inherit ) local Taylor expansions from a upper hierarchy level to the next lower hierarchy level. 

A typical feature of expert systems that support frames is inheritance. Frames can be organized in a hierarchical structure. They can inherit properties (attributes) from frames that are higher in the hierarchy. The latter are therefore called parent frame and the former child frame. There are many varieties of the inheritance principle. Frames can have only one parent frame (simple inheritance) or may have multiple parent frames (multiple inheritance). All attributes can be inherited (full inheritance) or only a few, selected by the knowledge engineer, may be inherited (partial inheritance) by the child frames. An example of a simple inheritance organization of frames is shown in Table 43.1. The frame Organic Compound is the parent frame. The frames Ester and Acids are child frames of Organic Compound . A typical example of inheritance is instantiation. The frame Acetic acid is a child of Acids and, since no extra attributes are added, it is also an instantiation. 

The basic idea of plugging in to a code framework shows up in different ways in different languages, including C++ templates, component/connector technologies, and class hierarchies. The latter tend to be overused it is often better to replace the inheritance with composition and explicit forwarding and to use types to document the subtle call patterns between superclasses and subclasses. 

There are different types of code reuse. Here we focus on code reuse using a class hierarchy—in other words, through inheritance. 

Notice that now each of these two classes extends Molstructure class and all common code is removed from them. This result is because the common behaviors are inherited from the common superclass—Molstructure. Also notice that even some logic in the constructor is inherited from the superclass. Now we have achieved some code reuse through inheritance by having a class hierarchy. 

The Physical Level contains all the nuts and bolts of the formulation domain in a number of information sources, including a database. The Physical Level is accessed from the Task Level via a query interface. The physical net contains the domain knowledge in a number of objects. An object consists of a set of attributes, each of which may have zero or more values. The objects are arranged in a classification hierarchy. Subobjects, which descend from another object, inherit their attributes and values. 

They define hierarchy and inheritance between concepts easily in a network format. 

KL-ONE is a frame-like family of knowledge representation approaches in the tradition of semantic networks [11], It was developed to overcome some of the drawbacks of semantic networks and represents conceptual information in a structured network for inheritance. The frames — in the KL-ONE approach called concepts — are arranged in a class-like hierarchy that includes the relations between frames. Frames are typically inherited from super classes. 

Multiple inheritance To propagate information through class-object hierarchies and exception and uncertainty handlers. 

The left hand side (x) may contain any number of clauses combined by Boolean algebra operators. In all but the simplest expert systems it is possible to include the expert s confidence in the conclusion. A frame describes hierarchical dependencies between objects. In a frame, the upper level (or parent) object passes attributes to the objects beneath it in the hierarchy (children). In other words, children inherit attributes from their parents. For example ... 

Frames An hierarchical method of representing knowledge in an expert system. Using the hierarchy, information is either explicitly stated or inherited from a higher level. Rules are also used to connect facts throughout the frames. Expert systems using frames will search hierarchies to associate facts with conclusions. 

Inheritance Some classes are subordinate to others and are called subclasses. Subclasses are considered to be special cases of the class under which they are grouped in the hierarchy. The variables and methods defined in the higher-level classes will be automatically inherited by the lower-level classes. 

Polymorphism Allows us to send the same message to different objects in different levels of class hierarchy. Each object responds in a way that is inherited or redefined with respect to the object s characteristics. 

Specialized subtypes of abstract module types can be specified as illustrated in lines 63-72. There, cpuc l, cpuc 2 and cpuc 3 inherit aU Behaviors, Guards- and Cause-Conditions of the abstract module cpuc and are specialized by the newly defined conditions. The concrete instances of these abstract modules are defined as cpuci in the modules cm l, cm 2 and cm 3 (see lines 124-139). In this way it is possible to build up a hierarchy of modules with different (sub-)module types in each hierarchy layer. 

The relationships between the production process, fibre properties, material structure, and the properties of the final product can be summarized in two diagrams. Figure 1.1 shows the general production route of textile materials from fibres to composites, and at the same time explains the structural hierarchy and inheritance of properties from parent products to those that result from further processing. Figure 1.2, in a simple form, encapsulates the relationships between the properties of fibres, processing technology, material structure, and the material s properties which are affected by temperature, humidity, and other environmental parameters. 

A hierarchy of cell models is often represented as a chain of models of various dimensionality (from ID to 3D). This picture is inherited from fluid dynamics, where 3D models traditionally have been considered as being superior over ID or 2D models. However, in fuel cell studies, the situation is more complicated. 

All attributes (and methods) are inherited along a single path. The hierarchy is a strict tree. 

The attributes and methods are inherited from different paths. A subclass that exhibits multiple inheritance allows the benefit of extracting the properties from a. several subcla.sses and U ees. The hierarchy as a whole is no longer a tree. 

Figure 2 Multiple inheritance in a class hierarchy provides additional design flexibility...

We could alternatively define bond subclasses in a multiple hierarchy. Intermediate subclasses would classify bonds based on a criterion such as the order and the elements involved in the bond. More specific subclasses would combine the criteria, leading to classes such as carbon-carbon single bonds , as shown in Figure 3. Note that, at the bottom level, each class inherits from precisely two superclasses. 

We have not included any attributes in a molecule to store its name or list of names. Clearly, it would be desirable to store both a common, short name as well as a systematic name for a molecule it would also be desirable to allow for additional names, and provide methods to manipulate these attributes. In our OOP representation of biochemical systems, we will provide a generic mechanism which relies on a superclass called named object . Then, all we need to do is designate the named object as a superclass of molecules all the attributes and methods are then automatically inherited. This is an example of software reuse facilitated by OOP. Once we abstract a very generic behavior in one system, we can use that same behavior in many other systems, through the class hierarchy and multiple inheritance mechanisms of OOP. 

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