Propositional calculus – Wikipedia, the free encyclopedia
Modus Ponens ((p → q) ∧ p) ├ q if p then q; p; therefore q
Modus Tollens ((p → q) ∧ ¬q) ├ ¬p if p then q; not q; therefore not p
Hypothetical Syllogism ((p → q) ∧ (q → r)) ├ (p → r) if p then q; if q then r; therefore, if p then r
Linguistic typology – Wikipedia, the free encyclopedia
Linguistic typology is a subfield of linguistics that studies and classifies languages according to their structural features. Its aim is to describe and explain the structural diversity of the world’s languages. It includes three subdisciplines: Qualitative typology deals with the issue of comparing languages and within-language variance, Quantitative typology deals with the distribution of structural patterns in the world’s languages, and Theoretical typology explains these distributions.
Verb Subject Object – Wikipedia, the free encyclopedia
Verb Subject Object (VSO) is a term in linguistic typology. It represents one type of languages when classifying languages according to the sequence of these constitutents in neutral expressions: Ate Sam oranges. The word order roughly corresponds to the order of symbols in (non-reverse) Polish notation or the S-expressions of the Lisp programming language.
Reverse Polish notation – Wikipedia, the free encyclopedia
[edit] The RPN algorithm
Generalizing the above example, we can easily describe a method to evaluate any RPN expression:
* While there are input tokens left o Read the next token from input. o If the token is a number Push it onto the stack. o Otherwise, the token is a function. (Operators, like , are simply functions taking two arguments.) It is known that the function takes n arguments. So, pop the top n values from the stack. # If there are fewer than n values on the stack * (Error) The user has not input sufficient values in the expression. Evaluate the function, with the values as arguments. Push the returned results, if any, back onto the stack. * If there is only one value in the stack o The value is the result of the calculation. * If there are more values in the stack o (Error) The user input too many values.
