Related Clues:

• It's empty
• It has no members
• Group with no members, in math
• It has zero measure, in math
• It's got nothing
• There's nothing to it
• Sell nonsense in head, there's nothing in it
• Empty math class
• Mathematical collection with nothing in it
• There’s nothing to it, in math
• After editing, tell Sun it's valueless
• Mathematical void symbolized by { }