Logic operators: How to create complex logical propositions

In this video we consider logic operators. The figure below shows a visual representation of how computers make decisions using logical propositions.

The black dot at the top indicates the starting point/flow of the program. Then there is a diamond which indicates a conditional. This is where the program will evaluate a logical expression to determine its truth (is it True or False?). If the condition (A) is True, then the program will follow the branch on the left and do (B). If the condition (A) is False, then the program will follow the branch on the right and do (C).

As a result, a program can do different things, depending on a condition. For example, your program may express as (A) the condition “if the window is open, and it’s raining” and your program will “close the window” as action (B) or “open the window” as action (C). Logical propositions are concerned with the condition (A).

We said that a logical proposition is an expression that can either be True or False, but can’t be both True and False. These expressions will usually express some truth about an event. For example, “is it raining outside” is a logical proposition which can either be True or False ( True if indeed it is raining outside or False if not).

We also said that we can create complex logic propositions using connectives (aka logical operators): AND, OR and NOT. There are more connectives than this, but in this course we focus on the very basic ones. In the next step we’ll revisit each one.