View difference between Paste ID: br5bj8iV and r1tmLdir

 %% Backward chaining
 
 -module(backward).
 -export([start/0,solveGoal/2,solveRule/2,collect/3,unify/2]).
 
 start() ->
 	Query = io:read("Enter query: "),
 	solveGoal(element(2, Query), self()),
 	receive
 		{_, Truth} -> io:format("Answer is: ~w~n", [Truth])
 	end.
 
-solveGoal(Goal,Caller) ->
+solveGoal(Goal, Caller) ->
     %% Fetch rules...
 	Rule = case Goal of
 		g -> [g,a,b,c];
 		a -> [a];
 		b -> [b];
 		c -> [c]
 	end,
-	Applicable = backward:unify(Goal,Rule),
+	Applicable = backward:unify(Goal, Rule),
 	if Applicable == true ->
 		if
 			%% If RHS is null
-			tl(Rule) == [] -> Caller ! {Goal,0.9};
+			tl(Rule) == [] -> Caller ! {Goal, 0.9};
 			%% If RHS contains subgoals
 			true -> spawn(backward, solveRule, [tl(Rule), self()])
 		end
 	%% If unify fails do nothing
 	end,
 	receive
 		%% Each message is of the form {goal,truth}
 		%% Just accept the 1st answer
 		{_, Truth} -> Caller ! {Goal, Truth}
 	end.
 
 solveRule(RuleTail, Caller) ->
 	N = length(RuleTail),
 	Collector = spawn(backward, collect, [[], N, Caller]),
 	%% For each subgoal in Rule
 	%% Spawn a process to solve each subgoal
 	lists:map(fun(Subgoal) -> spawn(backward, solveGoal, [Subgoal, Collector]) end,
 		RuleTail).
 
 %% Accumulate results
 collect(Truths, N, Caller) ->
 	%% If we have N messages send back the answer
-	%% Answer = min of list, equivalent to fuzzy-logic AND
+	%% Answer = min of truth values, equivalent to fuzzy-logic AND
 	if length(Truths) == N -> Caller ! {dont_care, lists:min(Truths)};
 	   true -> true
 	end,
 	receive
 		{_, Truth} -> collect([Truth | Truths], N, Caller)
 	end.
 
 %% Unify: just a stub
 unify(Goal,Rule) -> Goal == hd(Rule).