YES(?, 2*d + 5)

Initial complexity problem:
1:	T:
		(1, 1)    f2(a, b, c, d, e) -> f1(a, f, c, d, e) [ 1 >= a ]
		(1, 1)    f2(a, b, c, d, e) -> f300(a, b, c, d, e) [ a >= 2 /\ c >= 2 ]
		(?, 1)    f300(a, b, c, d, e) -> f1(a, f, c, d, e) [ d + 1 >= 0 ]
		(?, 1)    f300(a, b, c, d, e) -> f300(a, b, c, d + 1, e + 1) [ e >= 0 /\ 0 >= d + 2 ]
		(?, 1)    f300(a, b, c, d, e) -> f300(a, b, c, d + 1, e + 1) [ 0 >= e + 2 /\ 0 >= d + 2 ]
	start location:	f2
	leaf cost:	0

Repeatedly removing leaves of the complexity graph in problem 1 produces the following problem:
2:	T:
		(1, 1)    f2(a, b, c, d, e) -> f300(a, b, c, d, e) [ a >= 2 /\ c >= 2 ]
		(?, 1)    f300(a, b, c, d, e) -> f300(a, b, c, d + 1, e + 1) [ e >= 0 /\ 0 >= d + 2 ]
		(?, 1)    f300(a, b, c, d, e) -> f300(a, b, c, d + 1, e + 1) [ 0 >= e + 2 /\ 0 >= d + 2 ]
	start location:	f2
	leaf cost:	2

A polynomial rank function with
	Pol(f2) = -V_4 - 1
	Pol(f300) = -V_4 - 1
orients all transitions weakly and the transitions
	f300(a, b, c, d, e) -> f300(a, b, c, d + 1, e + 1) [ e >= 0 /\ 0 >= d + 2 ]
	f300(a, b, c, d, e) -> f300(a, b, c, d + 1, e + 1) [ 0 >= e + 2 /\ 0 >= d + 2 ]
strictly and produces the following problem:
3:	T:
		(1, 1)        f2(a, b, c, d, e) -> f300(a, b, c, d, e) [ a >= 2 /\ c >= 2 ]
		(d + 1, 1)    f300(a, b, c, d, e) -> f300(a, b, c, d + 1, e + 1) [ e >= 0 /\ 0 >= d + 2 ]
		(d + 1, 1)    f300(a, b, c, d, e) -> f300(a, b, c, d + 1, e + 1) [ 0 >= e + 2 /\ 0 >= d + 2 ]
	start location:	f2
	leaf cost:	2

Complexity upper bound 2*d + 5

Time: 0.226 sec (SMT: 0.215 sec)