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IsFactorClosed

test whether a list of PPs is factor closed

Syntax 
IsFactorClosed(L: LIST of power products): BOOL

Description
A set of power products is factor closed iff it contains every factor of every one of its elements. This function checks whether the given set is factor closed (also known as "order-ideal"). It is an error if L is empty.

Example 
/**/  use P ::= QQ[x,y,z];
/**/  IsFactorClosed([1, x, x^2]);
true
/**/  IsFactorClosed([one(P), y^2]);
false

See Also