:- module(_,_,[sr/bfall]).
% A circuit topology example:

% The actual circuit

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

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

% Some circuit 'theory'

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

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

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

% Some queries to find gates in the circuit:
% ?- inverter(In,Out).
% ?- and_gate(In1,In2,Out).
% ?- nand_gate(In1,In2,Out).