%------------------------------------------------------------------------------ %----The USA is a country. fof(usa,axiom, country(usa) ). %----The capital of every country is a beautiful big city fof(country_big_city,axiom, ! [C] : ( country(C) => ( big_city(capital_of(C)) & beautiful(capital_of(C)) ) ) ). %----Washington is the capital of the USA, and it's not a big city. fof(usa_capital_axiom,axiom, ( capital_of(usa) = washington & ~ big_city(washington) ) ). %----Every big city has crime. fof(crime_axiom,axiom, ! [C] : ( big_city(C) => has_crime(C) ) ). %----A big city is a city. fof(big_city_city,axiom, ! [C] : ( big_city(C) => city(C) ) ). %----There is some city that is beautiful and has (no) crime. fof(some_beautiful_crime,conjecture, ? [C] : ( city(C) & beautiful(C) & ~ has_crime(C) ) ). %------------------------------------------------------------------------------