i think, you can work on with this..
since , such that
actually this questions has got nothing to do with the above quetsion, which is above all my understandung, by the way..
but im new here so i kinda dont no how to deal with this forum example where to post my questions and where to go to may be help someone.. can any one help?
many helpful friends will read it and help you do it..
EDIT: i think you already know what to do..
Thanks Kalagota - I've got that far but haven't got further.
I think I can establish that if there's an identity element then it needs to be .
I think that if I can then establish that both and need to be equal to then the job is done.
I haven't been able to rule out the possibility that and need not be equal to .
And I can get no further.