Do opposite categories always exist?
123259
Maps in Opposite Categories
114773
counterexamples on modules
80260
Can it happen that the image of a functor is not a category?
92614
Does the Banach-Tarski paradox contradict our understanding of nature?
112906
Categories of mathematics
65176
When A and B are positively related variables, can they have opposite effect on their outcome variable C?
155592
Conditional conundrum
71250
Is this statement always true?
84378
Does axiom of foundation/regularity protect against Russell-like paradoxes?
87264
Are bicategories and lax 2-categories the same?
53421
What's the opposite of a cross product?
110376
Antonyms and mutually exclusive words
141299
Alternative set theories
113497
Is there a name for synonyms that appear to have opposite meanings?
106342
Why $L$-structures cannot satisfy a contradiction
77546
Does a "backwards" choice function imply the Axiom of Choice?
22057
Is it possible for something to have no cause?