User blog comment:B1mb0w/Recursion and Summation Functions/@comment-35470197-20190405011534/@comment-10262436-20190405015300

rule s5 is a little ambiguous. Here is what I intended:

t_0(c,s)(t_0(c+1,0)) = t_0(c,0)   in all cases.

i.e.

t_0(1,s)(t_0(2,0)) = t_0(1,0)

The use of C and D in this rule is unnecessary. I have tidied up the rule to make this clearer.