Modus tollens - Wikipedia
https://en.wikipedia.org/wiki/Modus_tollensExplanation. The form of a modus tollens argument resembles a syllogism, with two premises and a conclusion: . If P, then Q. Not Q. Therefore, not P.. The first premise is a conditional ("if-then") claim, such as P implies Q.The second premise is an assertion that Q, the consequent of the conditional claim, is not the case. From these two premises it can be logically concluded …
:not | CSS-Tricks - CSS-Tricks
https://css-tricks.com/almanac/selectors/n/not06.09.2011 · p:not(:nth-child(2n+1)) { font-size: 3em; } However, if we use a pseudo-element selector as our argument it will not produce the expected result.:not(::first-line) { /* ::first-line is a pseudo element selector and not a simple selector */ color: white; } Complex selectors. These are newer than the basic :not() selectors.
"If..., Then..."
math.hawaii.edu/~ramsey/Logic/IfThen.htmlWhat happens if you interchange (commute) P and Q in an "if...then"? Generally, you get a sentence with a different truth. For example, here is a true "if...then": if an animal is a bird, then it is a warm-blooded animal (this sentence is always true).