Topic 1.1. Logical expressions and operations

A Grade 8 topic in Computer Science: “Topic 1.1. Logical expressions and operations” (pp. 60–62, I. N. Tsybulya, L. A. Samykbaeva et al.). Logic is the science of correct thinking, of proving statements and of reaching decisions; in ancient Greek the word “logic” means “the science of reasoning”. Boolean algebra is one of the foundations of computer science: in 1847 the English mathematician George Boole proposed a mathematical method in which logical statements are denoted by short symbols. A simple logical statement is one that cannot be reduced or divided without losing its meaning. A compound statement consists of simple statements joined by logical connectives matching the logical operations. A logical expression is a set of logical statements joined by logical operations. The basic logical operations are disjunction (addition, “or”), conjunction (multiplication, “and”), implication (following, “if … then”), inversion (negation, “not”) and equivalence (“if and only if”). In the truth table 0 denotes a false statement and 1 denotes truth.