TAILIEUCHUNG - Lecture Formal methods in software engineering: Partial operator
After studying this chapter you will be able to understand: Defining a type partial operators, basic types, type constructors, the set type constructor, operators on sets, operators on sets selecting elements, refinement. | Formal Methods in SE Lecture 21 VDM II Qaisar Javaid, Assistant Professor 2 1 3 Defining a type Partial Operators An operator op : T1 * . . . * Tn -> R is said to be total if, for any a1:T1,. . . an:Tn, the expression op(a1,. . ., an) is defined. If there exists some b1:T1,. . .,bn:Tn for which op(b1,. . .,bn) is undefined, op is said to be a partial operator. We avoid applying partial operators to values on which they are undefined! 4 Basic Types Type Symbol nat nat1 int real char Bool quote Values Natural numbers nat excluding 0 Integers Real Numbers Characters Booleans Named quote values Example Values 0, 1, 2, 1, 2, 3, ,-1,0,1,2, ‘g’, ‘@’ true, false , Operators +,-,*,/, +,-,*,/, +,-,*,/, +,-,*,/, =, and, or, =, 5 Type Constructors
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