thys/turing_basic.thy
changeset 53 25b1633a278d
parent 52 2cb1e4499983
child 54 e7d845acb0a7
equal deleted inserted replaced
52:2cb1e4499983 53:25b1633a278d
   221     assume ind: 
   221     assume ind: 
   222       "\<And>tp'. steps (1, tp) A n = (0, tp') \<Longrightarrow>
   222       "\<And>tp'. steps (1, tp) A n = (0, tp') \<Longrightarrow>
   223       \<exists>n'. \<not> is_final (steps (1, tp) A n') \<and> steps (1, tp) A (Suc n') = (0, tp')"
   223       \<exists>n'. \<not> is_final (steps (1, tp) A n') \<and> steps (1, tp) A (Suc n') = (0, tp')"
   224     and h: " steps (1, tp) A (Suc n) = (0, tp')"
   224     and h: " steps (1, tp) A (Suc n) = (0, tp')"
   225     from h show  "\<exists>n'. \<not> is_final (steps (1, tp) A n') \<and> steps (1, tp) A (Suc n') = (0, tp')"
   225     from h show  "\<exists>n'. \<not> is_final (steps (1, tp) A n') \<and> steps (1, tp) A (Suc n') = (0, tp')"
   226       (*
       
   227       apply(simp add: step_red del: steps.simps)
       
   228       apply(case_tac "(steps (Suc 0, tp) A n)")
       
   229       apply(case_tac "a = 0")
       
   230       apply(simp)
       
   231       *)
       
   232     proof(simp add: step_red del: steps.simps, 
   226     proof(simp add: step_red del: steps.simps, 
   233                      case_tac "(steps (Suc 0, tp) A n)", case_tac "a = 0", simp)
   227                      case_tac "(steps (Suc 0, tp) A n)", case_tac "a = 0", simp)
   234       fix a b c
   228       fix a b c
   235       assume " steps (Suc 0, tp) A n = (0, tp')"
   229       assume " steps (Suc 0, tp) A n = (0, tp')"
   236       hence "\<exists>n'. \<not> is_final (steps (1, tp) A n') \<and> steps (1, tp) A (Suc n') = (0, tp')"
   230       hence "\<exists>n'. \<not> is_final (steps (1, tp) A n') \<and> steps (1, tp) A (Suc n') = (0, tp')"