/** ***************************************************************************************************************************
*this is only applicable using the database that Jamie has used during his lecture. in this case its lecture 17 [l17] database*
*************************************************************************************************************************** **/

addplus(4,5,9).
/** returns false **/

addplus(4,5,z).
/** returns an instanciation of z=4+5 **/

/** due to a crash of jove the lecture was more observed rather than coded**/

sum(10,S).
/** returns an instanciation of S=55, a sum of all numbers from 0 to the number input. it does so working down from 10 rather than up **/

sumofsquares(10,S).
/** returns an instanciation of S=385, for a sum of all squares from 0 to the number input **/

/** 
 * sum(0,0).
 * sum(N,S) :- N1 is N-1, sum(N1,S1),S is S1+N. 
**/
/** S1 is a subvariable for recursive call of the function. if N1 would be placed after the it would return "varialbes not fully instanciated" error **/

sumlist([1,2,3],S).
/** returns an instanciation of S=6. the sum of all items in the list **/

smlist([1,2,3,10],S).
/** returns an instanciation of S=16. **/