explain valid or invalid
95851
Validity of an argument with a contradictory conclusion
50733
Help to understand material implication
38167
What do I do when two squares are equally valid?
89938
Is the Formula Logically Valid?
63490
Can I use "reasonable" in place of "plausible" in the following context?
105545
Confused about language and words in logic
22193
Why, logically, is proof by contradiction valid?
18051
Negation of 2 things: "and" or "or"?
108990
What is the difference between "necessary" and "sufficient"?
99159
This is not valid housing. What is valid housing?
131288
form.valid() should not display validation text?
146260
Question about how to interpret arbitrary elements
40607
What does 'close invalidated' mean
43694
Prompt the user to input something else if the first input is invalid
64902
How to properly say that a given day/date does not exist?
43104
How should the "and/or" text of a card be interpreted?
42559
(Built-in) way in JavaScript to check if a string is a valid number