Proposition 3.3

Let be a primitive form, and let its Hessian. Recall that we write if F has a triple root in . Then

• if and only if F has at least a double root in , and if this is the case all the roots of F are in fact in itself.
• if and only if .
• If and , then if and only if . If then .
• If then we have the following: If , then . If but , then . If and , then there exists such that , and then .