The Lord's Prayer: as we forgive others

as i drove home from a memorial service i got to thinking about defining forgiveness. once again i had read believers claiming that forgiveness should be given only to those who ask for it. some believers with a lot of calfskin (multi-degreed) hold this view. but my observations are that those who withhold forgiveness only burden themselves and tie burdens onto their souls. immediately after the prayer Jesus teaches that our Father won't forgive us if we don't forgive others. but right before this we ask Father to forgive "us." who am i to ask Father to forgive someone i won't forgive.
what is forgiveness?
i made up my own definition without consulting dictionaries or commentaries so this could be totally wrong.
forgiveness is the relinquishing of my claim to justice.
when i relinquish my claim to justice i turn it over to our Father to handle. great article here.
see also an article about the effects of unforgiveness and anger
and responding to wrongs with blessing
using forgiveness to bring healing to others

update: the point asks these questions in light of the VT rampage.