Outline Examples of voting system -What should be an ideal voting system Arrow's Impossibility Theorem Main idea of the proof of Arrow's Impossibility Theorem Yes-no voting systems and the dimension of these systems. How to quantify political power -Examples of power indices and their applications to the LEGCO voting system.Outline ƒ Examples of voting system ƒ What should be an ideal voting system ? ƒ Arrow's Impossibility Theorem ƒ Main idea of the proof of Arrow's Impossibility Theorem ƒ Yes-no voting systems and the dimension of these systems. ƒ How to quantify political power ? ƒ Examples of power indices and their applications to the LEGCO voting system