E-Commerce

270E-Commerceof the bracket that includes a term is a component of a formula, we say that the formulaincludes the term. It is the same with a term and a factor. An example is shown below.The term a(b+c){d+e} has factors a, (b+c), {d+e}, and includes factors b, c, d, e.2.3 A Condition Formula SearchIf a user can specify search conditions, searches will become more functional whensearching data from data storage. Here, we introduce the function for specifying conditionsdefining a condition formula by Formula Expression into CDS. We call it a conditionformula search, which is one of the main functions of CDS.1) Logical operation. Let propositions P, Q be sets which include characters p, qrespectively. The conjunction, disjunction and negation of them in logical operation aredefined by Formula Expression as follows:1) ConjunctionP∧Q = p×q2) DisjunctionP∨Q = p+q3) Negation¬P = !p2) A condition formula processing map f. A formula created from these is called acondition formula. "!" is a special factor which means negation. Recursivity by () in FormulaExpression is supported so that the recursive search condition of a user is expressed by acondition formula. A condition formula processing map f is a map that gets a disjoint unionof terms which satisfies a condition formula from a formula. When condition formulaprocessing is considered, the concept of a remainder of spaces is inevitable. A remainderacquisition map g is a map that has a term that doesn’t include a specified factor. If youassume x to be a formula and p, !p, p+q, p×q, !(p+q), !(p×q) to be condition formulas, theimages of (x, p+q), (x, p×q), (x, !(p+q)), (x, !(p×q)) by f, g are the following:f(x, p) = g(x, !p)f(x, !p) = g(x, p)f(x, p+q) = f(x, p)+f(g(x, p), q)f(x, p×q) = f(f(x, p), q)f(x, !(p+q)) = g(g(x, p), q)f(x, !(p×q)) = g(f(f(x, p), q)Figure 2.3 shows each image by the condition formula processing map f. It is obvious thatany complicated condition formula can be processed using combinations of the above sixcorrespondences.