Define R$2=$ i

max $\backslash |$ xi$\backslash |2$

$2$ and $\backslash$rho $=$ i

minyi

wT

f

$\backslash |$ wf $\backslash |2$

xi$.$ We want to show that the number of

mistake corrections T to take for halting is T $<=\backslash$gamma $.(1)$ Express the upper bound $\backslash$gamma using the

two terms above. $(2)$ From the resulting $\backslash$gamma $,$ explain why it is hard to know how long halting

takes