They were discovered by Thorold Gosset, although only the demipenteract (and lower regular forms) were included in his regular and semiregular polytope list since he defined semiregular to mean only regular polytope facets could be used.
They were discovered by Thorold Gosset. Only the demipenteract (and lower regular forms) were included in his regular and semiregular polytope list. He defined. Semiregular to mean only regular polytope facets could be used.