SMU Professor of Finance Melvyn Teo has written to Straits Times Forum regarding Transport Minister Lui Tuck Yew's proposals to vary the supply of certificates of entitlement (COEs). Prof Teo argues that ?Setting strict limits on the amount of financing may be the simplest and most effective way to put the brakes on runaway COE premiums?. An excerpt of his letter appears in print; the full letter is available in ST Forum online.