anchor.diff:  
   (defun psr-atribuicoes-consistentes-arco-p (psr var1 v1 var2 v2)
   	(if (equal (psr-listconstrains psr) nil)
  -		(return-from
  -			psr-atribuicoes-consistentes-arco-p
  -				(values T 0)
  -		)
  -	)
  -
  -	(let
  -		(
  -			(testes 0)
  -			(aux1 (psr-variavel-valor psr var1))
  -			(aux2 (psr-variavel-valor psr var2))
  -		)
  -		
  -		(if (equal aux1 nil)
  -			(setf aux1 nil)
  -		)
  -		
  -		(if (equal aux2 nil)
  -			(setf aux2 nil)
  -		)
  -
  +		(return-from psr-atribuicoes-consistentes-arco-p (values T 0))
  +	)
  +	(let ((testes 0) (aux1 (psr-variavel-valor psr var1)) (aux2 (psr-variavel-valor psr var2)))
  +		(if (equal aux1 nil) (setf aux1 nil))
  +		(if (equal aux2 nil) (setf aux2 nil))
   		(psr-adiciona-atribuicao! psr var1 v1)
   		(psr-adiciona-atribuicao! psr var2 v2)
  -		
   		(dolist (r (psr-variavel-restricoes psr var1))
  -			(cond
  -				(
  -					(membro var2 (restricao-variaveis r))
  +			(cond ((my-member var2 (restricao-variaveis r))
   					(incf testes)
  -					(cond
  -						(
  -							(not (funcall (restricao-funcao-validacao r) psr))
  -							(psr-adiciona-atribuicao! psr var1 aux1)
  -							(psr-adiciona-atribuicao! psr var2 aux2)
  -							(return-from
  -								psr-atribuicoes-consistentes-arco-p
  -									(values nil testes)
  -							)
  -						)
  -				  )
  -				)
  +					(cond ((not (funcall (restricao-funcao-validacao r) psr))
  +						(psr-adiciona-atribuicao! psr var1 aux1)
  +						(psr-adiciona-atribuicao! psr var2 aux2)
  +						(return-from psr-atribuicoes-consistentes-arco-p (values nil testes))
  +						  )
  +				    )
  +				   )
   			)
   		)
   		(psr-adiciona-atribuicao! psr var1 aux1)
  
positive.code: ; ======================================================================================= ;
  
  
  ; TRANSFORMA FILL-A-PIX EM PSR
  
  ; Receives a corresponding array to a two-dimensional table mxn of a puzzle
  ; Fill-a-Pix unresolved and returns a PSR representing the problem to solve
  
negative.code: ; Returns a list of all restrictions applicable to this variable.
  
  (defun psr-variavel-restricoes (psr key)
      (let ( (ans NIL)
  		
  				)
  				
  		(setf psr psr)
        (setf ans (gethash key hashtableconstr)) 
        ans
        )
  )
  
  
  