Octadecagon and 2{9/4} or two enneagrams, {18/6} is reduced to 6{3} or 6 equilateral triangles, and finally {18/9} is reduced to 9{2} as nine digons. Deeper truncations of the regular enneagon and enneagrams can produce isogonal (vertex-transitive) intermediate octadecagram forms with equally spaced vertices and two edge lengths. Other truncations form double coverings: t{9/8}={18/8}=2{9/4}, t{9/4}={18/4}=2{9/2}, t{9/2}={18/2}=2{9}. The regular octadecagon is the Petrie polygon for a number of higher-dimensional polytopes, shown in these skew orthogonal projections from Coxeter planes: Octadecagon An octadecagon (or octakaidecagon) or 18-gon is an eighteen-sided polygon. A "regular octadecagon" has a Schläfli symbol {18} and can be constructed
How to Have Sex in an Epidemic How to Have Sex in an Epidemic How to Have Sex in an Epidemic: One Approach is a 1983 nonfiction manual by Richard Berkowitz and Michael Callen, under the direction of Joseph Sonnabend, to advise men who have sex with men (MSM) about how to avoid contracting the infecting agent which causes AIDS. It was among the first publications to recommend the use of condoms to prevent the transmission of STDs in men having sex with men, and has even been named, along with "Play Fair!," as one of the foundational publications in the advent of modern safe sex. The