An autogram (Greek: αὐτός = self, γράμμα = letter) is a sentence that describes itself in the sense of providing an inventory of its own characters. They were invented by Lee Sallows, who also coined the word autogram. An essential feature is the use of full cardinal number names such as "one", "two", etc., in recording character counts. Autograms are also called 'self-enumerating' or 'self-documenting' sentences. Often, letter counts only are recorded while punctuation signs are ignored, as in this example:
A type of autogram that has attracted special interest is the autogramic pangram, a self-enumerating sentence in which every letter of the alphabet occurs at least once. Certain letters do not appear in either of the two autograms above, which are therefore not pangrams. The first ever self-enumerating pangram appeared in a Dutch newspaper and was composed by Rudy Kousbroek. Sallows, who lives in the Netherlands, was challenged by Kousbroek to produce a self-enumerating 'translation' of this pangram into English—an impossible-seeming task. This prompted Sallows to construct an electronic Pangram Machine. Eventually the machine succeeded, producing the example below which was published in Scientific American in October 1984:
Sallows wondered if one could produce a pangram that counts its letters as percentages of the whole sentence–a particularly difficult task since such percentages usually won't be exact integers. He mentioned the problem to Chris Patuzzo and in late 2015 Patuzzo produced the following solution:
- This sentence is dedicated to Lee Sallows and to within one decimal place
- four point five percent of the letters in this sentence are a's, zero point one percent are b's,
- four point three percent are c's, zero point nine percent are d's, twenty point one percent are e's,
- one point five percent are f's, zero point four percent are g's, one point five percent are h's,
- six point eight percent are i's, zero point one percent are j's, zero point one percent are k's,
- one point one percent are l's, zero point three percent are m's, twelve point one percent are n's,
- eight point one percent are o's, seven point three percent are p's, zero point one percent are q's,
- nine point nine percent are r's, five point six percent are s's, nine point nine percent are t's,
- zero point seven percent are u's, one point four percent are v's, zero point seven percent are w's,
- zero point five percent are x's, zero point three percent are y's and one point six percent are z's.
Just as an autogram is a sentence that describes itself, so there exist closed chains of sentences each of which describes its predecessor in the chain. Viewed thus, an autogram is such a chain of length 1. Here follows a chain of length 2:
A special kind of autogram is the 'reflexicon' (short for "reflexive lexicon"), which is a self-descriptive word list that describes its own letter frequencies. The constraints on reflexicons are much tighter than on autograms because the freedom to choose alternative words such as "contains", "comprises", "employs", and so on, is lost. However, a degree of freedom still exists through appending entries to the list that are strictly superfluous.
For example, "Sixteen e's, six f's, one g, three h's, nine i's, nine n's, five o's, five r's, sixteen s's, five t's, three u's, four v's, one w, four x's" is a reflexicon, but it includes what Sallows calls "dummy text", which is only having one of some letter. Dummy text are in the form "one #", where "#" can be any typographical sign not already listed. Sallows has made an extensive computer search and conjectures that there exist only three pure (i.e., no dummy text) English reflexicons.