Notes from Structure and Interpretation of Computer Programs computational process - A running program that is able to alter data it has access to. (Computational processes are abstract beings that inhabit computers and manipulate other abstractionsa as they grow.) recursion equations - Deals with the recurrance of a specific reference. Something related to another event that has happened before, a cyclical behavior. procedures - A way to describe a process. data - Anything that can be manipulated by a process. expression - anything that returns a value. Can be single or compound. evaluating - computing an expression or term. combinations - an expression in Lisp that uses a primitive value inside of parentheses. Contains operators and operands. operator - a primitive expression operand - data that is being evaluated recursive - In order to evaluate one expression, another expression must first be evaluated until a base case is reached, meaning the simplest form of that expression. One of the steps in the procedure is to refer to itself. tree accumulation. - Values percolate upwards during a process. special forms - Information must be gathered from the environment in order to process the expression properly. These expressions go outside of the general evaluation rules. procedure definitions - A technique that allows the program to be more dynamic. It takes a compound operation and gives it a name. compound procedure - A non-simple evaluation of an expression or operation by following a sequence of steps. This allows it to be used as a building block in constructing further processes. substitution model - A model that searches for the meaning of an application or a procedure being used. normal-order evaluation - fully expand and then reduce in order to come to a conclusion. applicative-order evaluation - evalutate the arguments and then apply case analysis - A conditional deciding which flow of logic evaluates to true predicate - first condition in each pair, procedure that returns true or false clauses - pairs of expressions consequent expression - the return value of a certain conditional