How can a particular user among four users with same responsibility can have access to particular view and this view should not be visible to other users?

A1: yes by assigning the position and giving a unique,user id he can acess the data

A2: The new views which are to be restricted from the other 3 users can be grouped up in a seperate responsibility and then the 1st user can be assigned that the newly created responsibility. This will save time and will ensure smooth operations as well.

A3: think this is possible only by scripting. given view's item identifier should be '0'. we need to capture the USERID of the particular user. if that user id matches the login name then we need to change this view's item identifier to any other number other than zero.
this script should be written at application level.