- Duck is the common name for numerous species of waterfowl in the family Anatidae. Ducks are generally smaller and shorter-necked than swans and geese, which are members of the same family. Divided among several subfamilies, they are a form taxon; they do not represent a monophyletic group (the group of all descendants of a single common ancestral species), since swans and geese are not considered ducks. Ducks are mostly aquatic birds, and may be found in both fresh water and sea water.
- Turing kicked us out of Heaven (buttondown.com)
The halting problem is “undecidable”: there’s no algorithm which can tell you if an arbitrary program with an arbitrary input will halt or not. IE, if you give me a proposed “halt-detector”, I can inspect it and come up with a program and input for which it would give the wrong answer.