From researchgate: https://www.researchgate.net/post/What_is_the_actual_difference_between_1st_order_and_higher_order_logic
First and second-order logic formalizations
First and second-order logic formalizations
First and second-order logic formalizations
From researchgate: https://www.researchgate.net/post/What_is_the_actual_difference_between_1st_order_and_higher_order_logic