def retractOnWorld(cogstate,worldname,proposition): """ INPUT: a triple (cognitive state, worldname, proposition) OUTPUT: array of worlds WHAT IT DOES: Definition 4 (i) """ result=[] world=getWorldByName(worldname,cogstate) for situation in sitgen(world): # s if Forceable(situation, proposition, cogstate): continue # s may not force P adding=False for basis in getAllBases(world,cogstate): # s' if not subset(situation,basis): continue # s is has to be a subset of s' Maximal=True for t in subsitgen(basis): if Forceable(situation, proposition, cogstate): continue # t may not force P if subset(situation,t): if situation != t: Maximal=False if not Maximal: continue # s should be a maximal subset of s' adding=True if adding: result.append(situation) return result
from propositions import propositionFromFormula
from counterfactual import ifItHadBeenTheCase
language = ['p','q','r']
s0 = worldgen(language)
s1=updateFormula(s0, "r")
s2=updateLaw(s1, "(r)>((p)|(q))")
s3=updateFormula(s1, "p")
print "\nThis is s3:"
print(texify(s3))
print "\nThe bases of w_7 in s3 are: "
pprint(getAllBases(getWorldByName("w_7",s3),s3))
prop=propositionFromFormula(s3,"p")
print "\nThe retraction of w_7 with [[p]] is:"
pprint(retractOnWorld(s3,"w_7",prop))
print "\nThe retraction of s3 with [[p]] is:"
s4=retractOnState(s3,prop)
pprint(s4)
print(texify(s4))
s5=ifItHadBeenTheCase(s3,"~(p)")
