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In logic and mathematics, necessity and sufficiency are terms used to describe a conditional or implicational relationship between two statements.For example, in the conditional statement: "If P then Q", Q is necessary for P, because the truth of Q is guaranteed by the truth of P.
Sufficiency can be proven by demonstrating that a system can operate when the element in question is active without the influence of other elements. However, this does not indicate that the element in question is required for functioning. The element allows the system to function, but its presence is not required in order for the system to ...
If-then-else flow diagram A nested if–then–else flow diagram. In computer science, conditionals (that is, conditional statements, conditional expressions and conditional constructs) are programming language constructs that perform different computations or actions or return different values depending on the value of a Boolean expression, called a condition.
The corresponding logical symbols are "", "", [6] and , [10] and sometimes "iff".These are usually treated as equivalent. However, some texts of mathematical logic (particularly those on first-order logic, rather than propositional logic) make a distinction between these, in which the first, ↔, is used as a symbol in logic formulas, while ⇔ is used in reasoning about those logic formulas ...
Another form of argument is known as modus tollens (commonly abbreviated MT). In this form, you start with the same first premise as with modus ponens. However, the second part of the premise is denied, leading to the conclusion that the first part of the premise should be denied as well.
Traceability confirms that the requirement set satisfies the need (no more - and no less than what is required). To the above some add Externally Observable, that is, the requirement specifies a characteristic of the product that is externally observable or experienced by the user.
The Required NPSH (NPSH R): the head value at the suction side (e.g. the inlet of a pump) required to keep the fluid away from cavitating (provided by the manufacturer). NPSH is particularly relevant inside centrifugal pumps and turbines, which are parts of a hydraulic system that are most vulnerable to cavitation.
When referring to hypothetical future circumstance, there may be little difference in meaning between the first and second conditional (factual vs. counterfactual, realis vs. irrealis). The following two sentences have similar meaning, although the second (with the second conditional) implies less likelihood that the condition will be fulfilled: