4.
In the example LockManager implementation

a) A server votes No, if it has lost the connection to the client or the client
still waits for locks. (I.e. is in the LockQueue Vector in LockManager.java)

b) If transaction has asked to commit, it is supposed to have released all 
locks prior to committing (i.e. explicitly released). So a server votes No,
if either of the conditions in a) hold or the client still holds locks. 
(I.e. has entry in the locks Vector in LockManager.java)