Appendix:English hyphenation

English has certain conventions and tendencies toward writing compounds and affixed words solid, with a hyphen or with a space. There are no simple rules covering all cases. "A good learner’s dictionary will tell you how to write a prefixed word" ; this notion is supported by the chaotic complexity of patterns of actual usage. In some other languages, the rule is simple: almost never use hyphen in prefixed words; examples are in the translation table of anti-American.

The practice drifts over time and there are some differences in tendecies between the U.S. and the U.K.

Some words are written with a hyphen:
 * forget-me-not
 * father-in-law
 * thirty-three: a number word from 21 to 99

Usage guides
GPO manual recommends using a hyphen to avoid doubling a vowel except after short prefixes:
 * anti-inflation
 * micro-organism: however, microorganism is several times more common.

GPO manual (6.7.) recommends using a hyphen to avoid tripling a consonant, e.g. in shell-like.

GPO manual (6.34.) recommends using a hyphen after the prefixes ex-, self-, and quasi-.

GPO manual (6.35.) recommends spelling prefixed words where the second element is capitalized with a hyphen: anti-American. Other guides agree. transatlantic is an exception. .

See the referenced GPO manual in Wikisource for the complete set of recommendations.

OED2 entry for non- shows mostly hyphenated forms and notes that the hyphen is usually retained.

British vs. American usage
We can investigate changes in prevalence of hyphenation of prefixed words between British and American usage using Google Ngram Viewer corpora, with the use of frequency ratios. Some examples:
 * non-standard: nonstandard keeps gaining on non-standard in American usage, reaching the factor of 2.5 in 2019. By contrast, the ratio is rather stable after year 2000 in British usage, reaching 38% in 2019.
 * anti-aircraft: the ratio in favor of antiaircraft is rather stable after 2000 in the American corpus, reaching nearly 1.7 in 2019. By contrast, antiaircraft gained rapidly after 2000 in British corpus, reaching 50% in 2019.
 * anti-social: antisocial gained ground in both American and British corpora, reaching the factor of 15 in the American corpus and factor 2.24 in the British corpus.
 * pseudo-science: pseudoscience gains ground in both American and British corpora, reaching the factor of 5 in the American corpus and the factor of 2.5 in the British corpuse.
 * non-compositional: the hyphenated form outperformed the solid one by a factor of at least 1.7 in both corpora.

One cannot draw any sweeping conclusions from such a small sample, except for the following:
 * The ratios vary wildly between particular words.
 * American usage tends to favor solid spellings.
 * In American usage, hyphenation is widespread even if somewhat less common; for antiaircraft, the in-favor factor is only 1.7. For some words, the hyphenated form prevails despite GPO manual recommendation, an example being non-compositional.
 * British usage tends to favor hyphenated spellings, but antisocial is an exception.

The situation is different for prefixes for which GPO manual indicates they are written with a hyphen: ex-, self- and quasi-:
 * ex-teacher: the hyphenated form reaches the factor of over 14 or 20 in both corpora. Furthermore, Google scanning picks some hyphenations across the page as solid forms, so the solid exteacher performs even worse.
 * self-govern: the hyphenated form reaches the factor of over 10 in both corpora.
 * quasi-scientific: the hyphenated form reaches the factor of over 6 in both corpora

GPO manual favors adding a hyphen to prevent doubling of a vowel. Indeed:
 * anti-immigration: The hyphenated form reaches the factor of at least 6 in both corpora.
 * anti-inflation: The hyphenated form reaches the factor of at least 10 in both corpora.

The above would be a subject of a properly conducted academic study if one could be found.

Usage guides
GPO manual: "6.31. Print solid words ending in like, but use a hyphen to avoid tripling a consonant or when the first element is a proper name." Scotland-like is written with a hyphen.

Reliance on dictionaries
The Cambridge dictionary indicates that "A good learner’s dictionary will tell you how to write a prefixed word."

Guardian and Observer style guide lists individual words and then defers to Collins for hyphenation.

Australian government style manual directs the readers to "use the dictionary your organisation recommends and follow its hyphenation practices."

UNESCO style manual defers to Concise Oxford English Dictionary for hyphenation.

Which style guide
There are many style guides or manuals to choose from.

The U.S. Government Printing Office Style Manual is in public domain, stored in Wikisource, used by the U.S. government, and is fairly detailed about writing hyphens in prefixed words and compounds. Other guides available online tend to be much less detailed about hyphenation.