[math-fun] horizontal and vertical flip in Dihedral group (D4)

hi, iirc, the elements are : e, r, r2, r3, h, v, d1, and d2. does h flip about the x or y axis? is d1 / or \? or are there a more mnemonic set of element names? thanks --- ray tayek http://tayek.com/ actively seeking mentoring or telecommuting work vice chair orange county java users group http://www.ocjug.org/ hate spam? http://samspade.org/ssw/