A ket is a vector living in a dual
vector space to that containing bras. Bras and kets are commonly encountered in quantum
mechanics. Bras and kets can be considered as 1-vectors and 1-forms (or vice versa),
although this is almost always done only in a finite-dimensional vector
space.
is a vector living in a dual
vector space to that containing bras 
. Bras and kets are commonly encountered in quantum
mechanics. Bras and kets can be considered as 1-vectors and 1-forms (or vice versa),
although this is almost always done only in a finite-dimensional vector
space.
.
