Possible Clues:

• Proposition in math
• Maths proposition
• Formula the more complicated
• Diplomat (he or emissary) can issue proposition
• Rule requiring rock to be stored in the mine's entrance
• Those people hiding potentially valuable mass proposition
• Proposition nothing to do with article male pens
• Rule more flexible: article written on it
• Proposition in maths
• Proposition made by Greek boy concerning end of term?