types that have a demonintor are not Modularizable

denominator could become zero mod prime

Modular_arithmetic/doc_tex/Modular_arithmetic_ref/Modularizable.tex

@@ -5,28 +5,35 @@
 An algebraic structure is called \ccRefName, if there is a suitable mapping 
 into an algebraic structure which is based on the type \ccc{CGAL::Residue}. 
 For scalar types, e.g. Integers, this mapping is just the canonical homomorphism 
-into the type \ccc{CGAL::Residue}. For compound types, e.g. Polynomials, 
+into the type \ccc{CGAL::Residue} with respect to the current prime. 
+For compound types, e.g. Polynomials, 
 the mapping is applied to the coefficients of the compound type. 
 
 The mapping is provided via \ccc{CGAL::Modular_traits<Modularizable>}, 
 being a model of \ccc{ModularTraits}.
 
+Note that types representing rationals, or types which do have some notion 
+of denominator, are not \ccc{Modularizable}. 
+This is due to the fact that the denominator may be zero modulo the prime, 
+which can not be represented.  
+
+%\ccRefIdfierPage{CORE::BigRat}\\
+%\ccRefIdfierPage{CGAL::Gmpq}\\
+%\ccRefIdfierPage{leda::rational}\\
+%\ccRefIdfierPage{mpq_class}\\
+%\ccRefIdfierPage{CGAL::Quotient<NT>}\\
+
 \ccHasModels
 
 \ccRefIdfierPage{int}\\
 \ccRefIdfierPage{long}\\
 \ccRefIdfierPage{CORE::BigInt}\\
-\ccRefIdfierPage{CORE::BigRat}\\
 \ccRefIdfierPage{CGAL::Gmpz}\\
-\ccRefIdfierPage{CGAL::Gmpq}\\
 \ccRefIdfierPage{leda::integer}\\
-\ccRefIdfierPage{leda::rational}\\
 \ccRefIdfierPage{mpz_class}\\
-\ccRefIdfierPage{mpq_class}\\
 
-\ccRefIdfierPage{CGAL::Quotient<NT>}, depends on template argument.\\ 
 \ccRefIdfierPage{CGAL::Lazy_exact_nt<NT>}, depends on template argument.\\ 
-\ccRefIdfierPage{CGAL::Sqrt_extension<NT,ROOT>}, depends on template arguments.\\ 
+\ccRefIdfierPage{CGAL::Sqrt_extension<NT,ROOT>}, depends on template arguments.\\
 \ccRefIdfierPage{CGAL::Polynomial<Coeff>}, depends on template argument.\\ 
 
 \ccSeeAlso