its predecessor in the chain. Viewed thus, an autogram is such a chain of length 1. Here follows a chain of length 2: Reflexicons 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. Other variants There are many different variants to autograms. One such variant is by representing the letter frequencies using roman numerals: The frequency count can also be replaced with the decimal form rather than its corresponding english numerals form: See also Quine (computing) Diagonal lemma References External links Autograms in various languages Self-reference Word play Constrained writing