s793.py

from research import *
s=begin(793,'Separate index contraction from chronological duration','What does deleting one Kainan position do to every surviving name?',{},['File53 §3; C792'])
f=json.loads((ROOT/'model/BJ_head_index.json').read_text());names=[x['name'] for x in f];retained=names[:12]+['Kainan']+names[12:]
mapping=[{'name':n,'expunged_index':i+1,'retained_index':retained.index(n)+1,'difference':int(i>=12)} for i,n in enumerate(names)]
a=artifact('model/BJ_index_contraction.json',json.dumps(mapping,indent=2)+'\n')
finish(s,{'mapping':a,'retained_Kainan_index':13,'retained_Jacob_index':23,'unchanged_prefix':names[:12],'shifted_suffix':names[12:]},'One deletion changes ten surviving indices by one and leaves the twelve-name prefix fixed. Index change alone does not determine a chronological duration.','Reconstruct the complete57-year deletion ledger.',{'all_order':retained[:12]+retained[13:]==names,'ten_shifted':sum(x['difference'] for x in mapping)==10})