};
struct interaction * interaction_create (const struct variable *);
+struct interaction * interaction_clone (const struct interaction *);
void interaction_destroy (struct interaction *);
void interaction_add_variable (struct interaction *, const struct variable *);
void interaction_dump (const struct interaction *);
struct ccase;
-unsigned int interaction_case_hash (const struct interaction *, const struct ccase *);
+unsigned int interaction_case_hash (const struct interaction *, const struct ccase *, unsigned int base);
bool interaction_case_equal (const struct interaction *, const struct ccase *, const struct ccase *);
bool interaction_case_is_missing (const struct interaction *, const struct ccase *, enum mv_class);
int interaction_case_cmp_3way (const struct interaction *, const struct ccase *, const struct ccase *);