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  2. Commutative property - Wikipedia

    en.wikipedia.org/wiki/Commutative_property

    The Egyptians used the commutative property of multiplication to simplify computing products. [7] [8] Euclid is known to have assumed the commutative property of multiplication in his book Elements. [9] Formal uses of the commutative property arose in the late 18th and early 19th centuries, when mathematicians began to work on a theory of ...

  3. Commutativity of conjunction - Wikipedia

    en.wikipedia.org/wiki/Commutativity_of_conjunction

    In propositional logic, the commutativity of conjunction is a valid argument form and truth-functional tautology. It is considered to be a law of classical logic. It is the principle that the conjuncts of a logical conjunction may switch places with each other, while preserving the truth-value of the resulting proposition. [1]

  4. List of rules of inference - Wikipedia

    en.wikipedia.org/wiki/List_of_rules_of_inference

    The column-11 operator (IF/THEN), shows Modus ponens rule: when p→q=T and p=T only one line of the truth table (the first) satisfies these two conditions. On this line, q is also true. Therefore, whenever p → q is true and p is true, q must also be true.

  5. List of set identities and relations - Wikipedia

    en.wikipedia.org/wiki/List_of_set_identities_and...

    The great variety and (relative) complexity of formulas involving set subtraction (compared to those without it) is in part due to the fact that unlike ,, and , set subtraction is neither associative nor commutative and it also is not left distributive over ,, , or even over itself.

  6. Law (mathematics) - Wikipedia

    en.wikipedia.org/wiki/Law_(mathematics)

    In mathematics, a law is a formula that is always true within a given context. [1] Laws describe a relationship , between two or more expressions or terms (which may contain variables ), usually using equality or inequality , [ 2 ] or between formulas themselves, for instance, in mathematical logic .

  7. Proofs involving the addition of natural numbers - Wikipedia

    en.wikipedia.org/wiki/Proofs_involving_the...

    We prove associativity by first fixing natural numbers a and b and applying induction on the natural number c.. For the base case c = 0, (a + b) + 0 = a + b = a + (b + 0)Each equation follows by definition [A1]; the first with a + b, the second with b.

  8. Logical equivalence - Wikipedia

    en.wikipedia.org/wiki/Logical_equivalence

    In particular, the truth value of can change from one model to another. On the other hand, the claim that two formulas are logically equivalent is a statement in metalanguage, which expresses a relationship between two statements and . The statements are logically equivalent if, in every model, they have the same truth value.

  9. Truth table - Wikipedia

    en.wikipedia.org/wiki/Truth_table

    A truth table is a structured representation that presents all possible combinations of truth values for the input variables of a Boolean function and their corresponding output values. A function f from A to F is a special relation , a subset of A×F, which simply means that f can be listed as a list of input-output pairs.