Hi Lorenzo, I am trying to understand how the feature of relaxing preconditions in overridden functions work or should work. Given the situation, where I call an overridden function via base class reference: *struct Base { virtual void fun(bool b) = 0 precondition{ b == true }; }; struct Deriv : Base { void fun(bool b) override precondition{ true }; }; void test( Base & b ) { b.fun(false); **// broken contract or not?** }* Should this be treated as a broken contract or not? My reading of the documentation says that contract is not broken (because the "logic-or<http://contractpp.svn.sourceforge.net/viewvc/contractpp/releases/contractpp_0_4_0/doc/html/contract__/contract_programming_overview.html#logic_or_anchor>" logic applies), but I feel that whoever implemented function *test *made a mistake: he cannot assume what type will be implementing "interface" *Base*, so he cannot rely on the precondition being relaxed (even if he gets away with it this time). Regards, &rzej