resistor(power,n1).
	resistor(power,n2).

	transistor(n2,ground,n1).
	transistor(n3,n4,n2).
	transistor(n5,ground,n4).

/*
	inverter(Input,Output) :-
		Output is the inversion of Input.
*/

	inverter(Input,Output) :-
		transistor(Input,ground,Output),
		resistor(power,Output).

/*
	nand_gate(Input1,Input2,Output):-
	   Output is the logical nand of Input1 and Input2.
*/

	nand_gate(Input1,Input2,Output) :-
		transistor(Input1,X,Output),
		transistor(Input2,ground,X),
		resistor(power,Output).

/*
	and_gate(Input1,Input2,Output):-
	  Output is the logical and of Input1 and Input2.		     
*/

	and_gate(Input1,Input2,Output) :-
		nand_gate(Input1,Input2,X),
		inverter(X,Output).

%	Program 2.2: A circuit for a logical and-gate