if two objects are rubbing each other, then they are moving against each other
hugging is not humans_touching_each_other. rubbing is not friction. humans_touching_each_other is situation_involving_physical_contact. butting_against is not touching. if rub does not occur then touch occurs. massage is rubbing. touching is not touching. rubbing is friction. butting_against is touching. humans_touching_each_other is not situation_involving_physical_contact.