If-then statement

Fuzzy Logic Control The apphcation of fuzzy logic to process control requires the concepts of Fuzzy rules and fuzzy inference. A fuzzy rule, also known as a fuzzy IF-THEN statement, has the form ... 

Rules seemingly have the same format as IF.. THEN.. statements in any other conventional computer language. The major difference is that the latter statements are constructed to be executed sequentially and always in the same order, whereas expert system rules are meant as little independent pieces of knowledge. It is the task of the inference engine to recognize the applicable rules. This may be different in different situations. There is no preset order in which the rules must be executed. Clarity of the rule base is an essential characteristic because it must be possible to control and follow the system on reasoning errors. The structuring of rules into rule sets favours comprehensibility and allows a more efficient consultation of the system. Because of the natural resemblance to real expertise, rule-based expert systems are the most popular. Many of the earlier developed systems are pure rule-based systems. 

Develop a theoretical decision rule in the form of if... then statement... 

The team also states the action level in numerical terms and verifies that the proposed measurement methods have adequate sensitivity to meet the stated action levels. Finally, the team develops a decision rule expressed as an if... then statement that links the parameter of interest, the scale of decision-making, the action level, and the alternative action. 

The complexity of the problem would lead to code that is not maintainable in particular, if rules are built in using if-then approaches, the complexity of code may increase dramatically. If code contains more than 20 lines of if-then statements, it is usually a good idea to think about a rule-based approach. 

In the second phase, a less deterministic approach to knowledge implementation was chosen. A set of preliminary rules in the form of "If. . . then. statements was developed, and the set was grouped into categories such as landfills, above-ground contamination, and removal options and issues. The knowledge engineers rewrote the rules using PRL syntax, and these new rules formed the... 

The If...Then statement is a one-liner statement, with the syntax... 

An important concept in the absorption modeling of any extravascular administered drug is that the absorption process is independent of distribution and elimination. Hence, in accounting for these different formulations all that needs to be accounted for is the absorption process because distribution and elimination is usually the same regardless of how the drug is absorbed. Hence, different formulations are usually accorded their own absorption model through a series of IF-THEN statements with one formulation being the reference formulation. Thus, a solution and capsule may be modeled as... 

The second type of Structured English process is a conditional statement. A case statement is declared, followed by a group of possible actions that will be executed after the evaluation of the case. Programmers refer to this as an if/then statement. An example of a conditional statement is ... 

Decision structure tables are a print version of if, then statements (the what if scenario) in computer programs. They also are known as protocols or contingency tables see Table 21 for an example. They unambiguously describe complex, multivariable, multirule decision systems. A spreadsheet is a computerized decision structure table. 

Let us write down, therefore, further subdivisions in our fuzzy logical hierarchy. We will start by writing some of them down in terms of IF. . . THEN statements, which we will then convert to logical implications. The complete hierarchy to be used here is shown in Fig. 10.6. It is emphasised that the lowest statements in this hierarchy may also be further subdivided entirely as required for the problem under consideration. 

Line Numbers Should Double as Editing Aids and Targets of GOTO and if-then Statements... 

The trouble was that not all versions of BASIC allowed this feature about half did but the other half did not. Those that did allow multiple statements used different symbols as separators—a colon ( ), a solidus (/), or a comma (,). As popular as this feature is, it can become a user trap in at least one version of BASIC that appeared in the late 1970s. (A user trap is a feature whose interpretation is not self-evident and that may induce mistakes.) A concrete example is this Many versions of BASIC extended the IF-THEN statement to allow more than line numbers to appear after the word THEN. For example,... 

To be sure, both the general loop and the general IF-THEN-ELSE can be constructed using GOTO and IF-THEN statements, but that is not the point. Programmers tend to make fewer errors when the language they are using provides the constructs they need to carry out their work. 

Besides relying on line numbers as targets for the GOTO and IF-THEN statements, this construction is difficult to follow because the test (line 300) checks for a wrong answer rather than a right answer. Contrast this with a more modern way to make this choice ... 

Expert systems Typically computer-based heuristics or rules for forecasting. These rules are determined by interviewing forecasting experts and then constructing if-then statements. 

There are several categories of expert systems, but by far the most popular are the rule-based expert systems. Most rule-based expert systems are created with an expert system shell. The first successful rule-based expert system shell was the OPS 5 of Digital Equipment Corporation (DEG), and the most popular modern systems are CLIPS, developed by the National Aeronautics and Space Administration (NASA) in 1985, and its Java clone, Jess, developed at Sandia National Laboratories in 1995. All rule-based expert systems have a similar architecture, and the shells make it fairly easy to create an expert system as soon as a knowledge engineer gathers the knowledge from a domain expert. The most important component of a rule-based expert system is its knowledge base of rules. Each rule consists of an if-then statement... 

A step-by-step procedure for solving a problem that contains conditional logic (if/then) statements (SMDMC, 1992)... 

In the methodology developed by Watano et al. (50,51), four fuzzy variables were used, namely ZR (zero), PS (positive small), PM (positive medium) and PL (positive large). The values of D t), AD t) and V(t) were all classified into these four categories. Ten rules were proposed to relate measured D(t) and AD(t) with V((). Consequently, V(t) can be quantified using the if-then statement. An example is given as follows ... 

Scientists use generalizations about the data to formulate a hypothesis, or testabie statement. The hypothesis serves as a basis for making predictions and for carrying out further experiments. Hypotheses are often drafted as "if-then statements. The "then part of the hypothesis is a prediction that is the basis for testing by experiment. Figure 1.2 shows data collected to test a hypothesis. 

Philosophical reasoning and especially logical inferences need propositions, which refer to relational content with meaning for further rational thinking possibilities and they are declarative in the forms of IF-THEN statement implications. Each logical statement is a proposition with its antecedent and consequent parts that imply IF (antecedent) THEN (consequent) sort of relationships. 

To illustrate the use of qualitative knowledge in AED, consider the liquid storage system in Fig. 10.5. Using qualitative concepts such as low, normal and high, an AED would be indicated if the following logical IF-THEN statement is true based on measurements of q, q2, 3, and dhidt ... 

Kennedy (1991) defines an enthymeme as a rhetorical syllogism, i.e., a statement with a supporting reason introduced by for, because, or since or an if.. . then statement. In contrast to a logical syllogism, the premises and conclusion are ordinarily probable, not necessarily logically valid. A premise may be omitted if it will be easily assumed by the audience (Kennedy, 1991,... 

Identical functionality does not mean identical circuits. A behavioural VHDL description that uses a Case statement can have an identical function to a description constructed from If-then statements. However, as the synthesized circuits illustrated in Chapter 4, the characteristics of the circuits generated are very different, aldiough functionally identical. Chapter 4 further illustrated that the same behaviour can be created using ei er concurrent or sequential logic constructs. The choice of statement type can have a significant impact on circuit characteristics. 

Fuzzy control uses experience instead of differential equations to determine desirable control actions. Fuzzy control consists of implementation of rules, in the format of IF... THEN statements, which relate the input variables to the control action. The process begins by first defining membership functions to classify the inputs and outputs using linguistic terms. In structural control applications, the inputs are usually a combination of structural responses displacement, velocity, and acceleration. The input values are then converted to fuzzy values, using the membership functions. This step is referred to as fuzzification. The next step is... 

A fuzzy system maps an input spaee to an output spaee by means linguistic rules, which is based on human reasoning. The linguistie representation presents an intuitive, natural description of a system allowing for relatively easy algorithm development compared to numerical systems. A fuzzy linguistic mle consists of an IF-THEN statement. A fuzzy mle is evaluated by means of fuzzy operators such as fuzzy AND , fuzzy OR etc. For example, in the case of two inputs (A and I2) and single output (O) fuzzy system, it can be expressed as shown below ... 

Fuzzy logic systems are knowledge-based or rule-based systems constructed from human knowledge in the form of fuzzy IF-THEN rales (Wang (1997)). An important contribution of fuzzy system theory is that it provides a systematic procedure for transforming a knowledge base into non-linear mapping. A fuzzy IF-THEN rule is an IF-THEN statement in which some words are characterised by continuous membership functions. 

The ELSE part of the statement is optional. If the else part is not used, the statement simply is called an if-then statement. Some examples of if-then-else statements... 

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