#math - Mon 5 Mar 2007 between 02:11 and 02:25

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sparrWhere can I find a list of polyhedra with information about how many faces and edges meet at each vertex?
TRWBWokay, a second set of rules. a>b <=> c*a>c*b if c>0. a>b <=> c*a<c*b if c<0. if c=0, then c*a=c*b=0 and it tells you nothing
FatalErrorSpark, wikipedia probably
sparr even
sparrFatalError: the normal info is there, face/vertex/edge counts, but not what i need
schmityTRWBW: so i cant multiply by x+5
TRWBWsparr: just to make it simple, every polygon has the same number of edges and faces meeting at a vertex
schmity: you can. you just need keep track of the two cases, x+5<0 and x+5>0, and handle them separately
sparrTRWBW: polyhedra, not polygons
TRWBWsparr: yeah, polyhedron.
sparrTRWBW: and thats only true for regular polyhedra. im interested in all the other "common" non-regular polyhedra, like a soccer ball (Truncated icosahedron)
for which it is ALSO true, so i guess thats a bad example :)
schmityTRWBW: so how do i solve it then? yeah sorry i know you already posted it but im stupid at this
TRWBWschmity: read the rules i gave you. there were two sets, 2 ways of doing it. you need at some point to break down the denominators into negative and positive and handle certain cases differently.
schmityahhh
so i need to do test intervals?
TRWBWschmity: in each case, and it depends on the two ways of doing it, you transform it into something else based on the sign.
sparrTRWBW: im interested in polyhedra where some vertices have 3 edges, some have 4, and/or some have 5
TRWBWsparr: at this point i don't even know what you mean by polyhedra, but my suggesting is what FatalError said, start with wikipedia, maybe planetmath. maybe just search polyhedra. btw, i don't even know what definition of polyhedra you are using. might be good to start with something mathematically rigorous.
sparrTRWBW: erm... a solid constructed of polygonal faces. my conception is a lot more specific than that, i guess, since im only thinking of convex polyhedra with some sort of symmetry
schmityaright thanks dude
thanks TRWBW
TRWBWnp
schmityim still only getting 2 numbers
but thanks
TRWBWsparr: good luck.
sparrTRWBW: consider a pentagonal prism 'capped' by two pentagonal pyramids. 5 square faces, 10 triangular faces. the vertices of the square faces each connect to 4 edges, while the vertices at the top (/bottom) of the pyramids connect to 5 edges.
schmityhey TRWBW im only getting x =-1 and x =-5 for test intervals
TRWBWschmity: no it's not test intervals, and anyways it shold be -5 and -3/2
schmityhow do you get -3/2
TRWBWschmity: 2x+3=0
schmitybut you need to put that on the other side dont you?
TRWBWschmity: did i misremember your problem?
schmityidk
im feeling retarded
TRWBWthey aren't test intervals. they are intervals in which you can apply operations like multiplying by x+5 or doing 1/a < 1/b and get the right answer.
schmityTRWBW: is it right that i get (7x - 7)/(x+5) > 0
TRWBW: wtf are you talking about
sparrTRWBW: mathworld doesnt have such a list, plus their individual polyhedra pages have horrible flash animation
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