A binary decision is a choice between two alternatives, for instance between taking some specific action or not taking it.[1]
Binary decisions are basic to many fields. Examples include:
See also: Binary decision diagram. A binary decision diagram (BDD) is a way to visually represent a boolean function. One application of BDDs is in CAD software and digital circuit analysis where they are an efficient way to represent and manipulate boolean functions.[6]
The value of a boolean function can be determined by following a path in its BDD down to a terminal, making a binary decision at each node where a solid line is followed if the value of the variable at the node is true and a dotted line if it is false. A BDD is said to be 'ordered' if the order of the variables tested is fixed. A BDD is said to be 'reduced' if the two following conditions are true:
BDDs that are ordered and reduced can be called Reduced Ordered Binary Decision Diagrams (ROBDD). An example of a ROBDD is the figure to the right, which represents the function
f(x1,x2,x3)=\bar{x}1\bar{x}2\bar{x}3+x1x2+x2x3
x1
x2
x3
In computer science, conditional statements are used to make binary decisions.[9] A program can perform different computations or actions depending on whether a certain boolean value evaluates to true or false.
The if-then-else construct is a control flow statement which runs one of two code blocks depending on the value of a boolean expression, and its structure looks like this:
if condition then
code block 1
else
code block 2
end
The conditional expression is condition, and if it is true, then code block 1 is executed, otherwise code block 2 is executed. It is also possible to combine multiple conditions with the else-if construct:
if condition 1 then
code block 1
else if condition 2 then
code block 2
else
code block 3
end
This can be represented by the flow diagram on the right. If one condition is found to be true, then the rest are skipped, so only one of the three code blocks above can be executed.A while loop is a control flow statement which executes a code block repeatedly until its boolean expression becomes false, making a decision on whether to continue repeating before each loop. This is similar to the if-then construct, but it can executing a code block multiple times.