November 2025
Beginner
416 pages
8h 6m
English
Content preview from Logic For Dummies, 2nd Edition
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Chapter 18
Expanding Logical Relations
IN THIS CHAPTER
Understanding QL relational expressions
Unmasking identities
Writing proofs using relations and identities
In sentential logic (SL), you represent a basic statement with just one letter — a constant. For example, you can translate the statement “Barb is a tree surgeon” as
B |
(SL translation) |
In quantification logic (QL), you represent the same sentence with a two-letter combination of a property constant and an individual constant. For example:
|
(QL translation) |
This representation works great. But suppose you want to translate the statement “Barb hired Marty” into QL. Now that more than one person is in the picture, you need a way to express their relationship.
Or suppose you want to translate the statement “Barb is the best tree surgeon in the county.” In this case, you aren’t describing a property that applies to Barb, but rather her identity as the single best tree surgeon in the county.
Fortunately, QL allows you to express these more sophisticated ideas easily. In this chapter, I discuss both relations ...
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.