Express each of these system specifications using predicates, quantifiers, and logical connectives.
- At least one mail message, among the nonempty set of messages, can be saved if there is a disk with more than 10 kilobytes of free space.
- Whenever there is an active alert, all queued messages are transmitted.
- The diagnostic monitor tracks the status of all systems except the main console.
- Each participant on the conference call whom the host of the call did not put on a special list was billed.