Recent content by mbarby

guys guys guys. i bought the book with enthusiasm to begin to understand the mechanics of the quantum world. i have to say that for and outsider (i am a computer engineer with no quantum related physics background) the book is rather good. it is giving different examples. if you are a physicst...

to prove that i use the triangular inequality d(x,A) <= d(x,y)+d(y,A) d(x,A) - d(y,A) <= d(x,y) ---> -d(x,y) <= d(x,A) - d(y,A) <= d(x,y) but honestly i couldn't connect it to any kind of a proof :/ ...

hi all, i am studying from croom's introduction to topology book. i came across such a question. and i don't have a clue as to how to start . Let X be a metric space with metric d and A a non-empty subset of X. define f:X->IR by : f(x): d(x,A), x E X (x is an element of X) show that f is...

thx all guys, that eased my mind. i was tearing myself apart to understand where i was making the mistakes :/ ...

thx a lot this explains a great to me. is it true , then , if i say any interval having the border of the interval is open, or sth similar to that ?

sorry for the questions , i am not a math guy. but topology is one of the topics i want to learn. so somethings are as clear to me as it is to you guys. (0,1) is the space's itself. so we can't take an interval of (1-e, 1+e) without exceeding 1 by +e. but what i get from your reaction is that we...

what really confuses me here is that: lets assume 1 is accumulation point in (0,1) then shouldn't it be contained in an interval like (1-e, 1+e) (e=epsilon) but we don't have 1+e since it exceeds interval border.. where am i wrong now ?

are 0,1 accumulation points in (0,1) ? how about in [0,1] ? if 0 and 1 are accumulation points in [0,1] interval what is the open subset they are in ? i need explanation about this...pls...

thx for the help, i will have to go through all this once more , i think :). ...

but the result of the unions itself is of the form (x,y] . so this is considered open i guess...

let me rephrased this so that i understand it right: when we say open we mean open in the topological sense, i.e. if (0,1] is given as open then all the open subsets should be in the form of (x,y], is that right ?

hi, the subject seems rather cold. but there are things i still can't comprehend after reading your discussions several times. for example why can't we take (0 , 1/n(k) ) U ( 1/n(k+1), 1) for simplicitys sake. this is a finite subcover is it not ? (k are indexes) ps: i am not a mathematician...