Rule Doesn't Execute - rules

Question

I am currently creating an expert system to ask the user questions, which the answers will determine what the animal is? e.g. is the animal big? if user says yes - go on to relevant question - does it have long neck - if yes - it is a giraffe. When I am running the code I am only getting back the first question which is "Is the animal big yes or no?" when I respond with yes/no, nothing else appears, when I am hoping for the next relevant question to appear. This is the code/rules I already have included. Any guidance would be much appreciated.
(deffacts startup (animal mouse) (animal squirrel) (animal hamster) (animal giraffe) (animal elephant) (animal hippo) (animal rhino))
=>
(defrule is-animal-big (not (animal-big ?)) => (printout t "Is the animal big (yes or no)?") (assert (animal-big (read))))
(defrule yes-big
(big yes)
=>
(defrule is-neck-long (not (neck-long ?)) => (printout t "Is the animals neck long (yes or no)?") (assert neck-long (read))))
(defrule neck-long-yes
(neck-long yes)
=>
(printout t "your animal is a giraffe" crlf)
(bind ?animal giraffe)
(assert (animal-is ? animal)))
;;;===================================
(defrule neck-long-no
(neck-long no)
=>
(defrule is-nose-long (not (nose-long ?)) => (printout t "Is the animals nose long (yes or no)?") (assert (nose-long (read))))
(defrule nose-long-yes
(nose-long yes)
=>
(printout t "your animal is an elephant" crlf)
(bind ?animal elephant)
(assert (animal-is ?animal)))
;;;==============================
(defrule nose-long-no
(nose-long no)
=> (defrule does-swim-alot (not (swim-alot ?)) => (printout t "Does the animal swim a lot (yes or no)?") (assert (swim-alot (read))))
(defrule swim-alot-yes
(swim-alot yes)
=>
(printout t "your animal is a hippo" crlf)
(bind ?animal hippo)
(assert (animal-is ?animal)))
;;;===============================
(defrule swim-alot-no
(swim-alot no)
=>
(printout t "your animal is a rhino" crlf)
(bind ?animal rhino)
(assert (animal-is ?animal)))
;;;===============================
;;;*******************************
(defrule big-no
(big no)
=>
(defrule does-animal-squeak (not (animal-squeak ?)) => (printout t "Does the animal squeak (yes or no)?") (assert (animal-squeak (read))))
(defrule animal-squeak-yes
(animal-squeak yes)
=>
(printout t "your animal is a mouse" crlf)
(bind ?animal mouse)
(assert (animal-is ?animal)))
;;;==============================
(defrule animal-squeak-no
(animal-squeak no)
=>
(defrule animal-tail-bushy (not (tail-bushy ?)) => (printout t "Is the animals tail bushy (yes or no)?") (assert (tail-bushy (read))))
(defrule (tail-bushy-yes
(tail-bushy yes)
=>
(printout t "your animal is a squirrel" crlf)
(bind ?animal squirrel)
(assert (animal-is ?animal)))
;;;==============================
(defrule (tail-bushy-no
(tail-bushy no)
=>
(printout t "your animal is a hamster" crlf)
(bind ?animal hamster)
(assert (animal-is ?animal)))
;;;=============================
;;;*****************************

Answer 1

I suppose, that you want either the rule big-no or big-yes to fire after answering the first question. However, answering the first question will either assert (animal-big yes) or (animal-big no). In contrary to that, the precondition of big-no and big-yes are checking for (big ?) and not (animal-big ?). So these rules will never fire.
Additionally I would suggest, that you refactor your code in order to seperate the different rules more clearly. Judging the code that you postet, it wont work anyways. Did you try to create a new rule in the RHS of another rule?
For example:
(defrule yes-big
(big yes)
=>
(defrule is-neck-long (not (neck-long ?)) => (printout t "Is the animals neck long (yes or no)?") (assert neck-long (read))))
(defrule neck-long-yes
(neck-long yes)
=>
(printout t "your animal is a giraffe" crlf)
(bind ?animal giraffe)
(assert (animal-is ? animal)))
I would rewrite as
(defrule yes-big-check-neck
(animal-big yes)
(not (neck-long ?))
=>
(printout t "Is the animals neck long (yes or no)?")
(assert neck-long (read))
)
(defrule neck-long-yes
(neck-long yes)
=>
(printout t "your animal is a giraffe" crlf)
(bind ?animal giraffe)
(assert (animal-is ? animal))
)