Need help with finishing this proof.
Question
Let {x1 , . . . , xk} be a linearly independent finite set in a normed linear space. Show that there exists delta > 0 such that the condition
max||xi-yi||<delta ,1<=i<=k
implies that {y1 , . . . , yk} is also linearly independent
proof:
Assume {y1 , . . . , yk} is also linearly dependent
there exist c1,...,ck not all zero s.t.
c1y1+...+ckyk=0
WLOG suppose c1=1
yi=xi+ei, ,1<=i<=k (where ei is really small)
c1(x1+e1)1+...+ck(xk+ek)=0
c1x1+...+ckxk=-(c1e1+...+ckek)
RHS span{x1,..xk}
therefore,
c1e1+...+ckek=t1x1+...+tkxk
Now, I don't know what
to do. I know i need to use that fact that the norms are equivalent to
prove that c1 cannot equal 1, but I don't know how to do it.
Thankful for any help