(0) Obligation:
The Runtime Complexity (innermost) of the given
CpxTRS could be proven to be
BOUNDS(1, n^1).
The TRS R consists of the following rules:
f(x, c(y)) → f(x, s(f(y, y)))
f(s(x), y) → f(x, s(c(y)))
Rewrite Strategy: INNERMOST
(1) CpxTrsToCdtProof (BOTH BOUNDS(ID, ID) transformation)
Converted Cpx (relative) TRS to CDT
(2) Obligation:
Complexity Dependency Tuples Problem
Rules:
f(z0, c(z1)) → f(z0, s(f(z1, z1)))
f(s(z0), z1) → f(z0, s(c(z1)))
Tuples:
F(z0, c(z1)) → c1(F(z0, s(f(z1, z1))), F(z1, z1))
F(s(z0), z1) → c2(F(z0, s(c(z1))))
S tuples:
F(z0, c(z1)) → c1(F(z0, s(f(z1, z1))), F(z1, z1))
F(s(z0), z1) → c2(F(z0, s(c(z1))))
K tuples:none
Defined Rule Symbols:
f
Defined Pair Symbols:
F
Compound Symbols:
c1, c2
(3) CdtRuleRemovalProof (UPPER BOUND(ADD(n^1)) transformation)
Found a reduction pair which oriented the following tuples strictly. Hence they can be removed from S.
F(z0, c(z1)) → c1(F(z0, s(f(z1, z1))), F(z1, z1))
We considered the (Usable) Rules:none
And the Tuples:
F(z0, c(z1)) → c1(F(z0, s(f(z1, z1))), F(z1, z1))
F(s(z0), z1) → c2(F(z0, s(c(z1))))
The order we found is given by the following interpretation:
Polynomial interpretation :
POL(F(x1, x2)) = x2
POL(c(x1)) = [1] + x1
POL(c1(x1, x2)) = x1 + x2
POL(c2(x1)) = x1
POL(f(x1, x2)) = x2
POL(s(x1)) = 0
(4) Obligation:
Complexity Dependency Tuples Problem
Rules:
f(z0, c(z1)) → f(z0, s(f(z1, z1)))
f(s(z0), z1) → f(z0, s(c(z1)))
Tuples:
F(z0, c(z1)) → c1(F(z0, s(f(z1, z1))), F(z1, z1))
F(s(z0), z1) → c2(F(z0, s(c(z1))))
S tuples:
F(s(z0), z1) → c2(F(z0, s(c(z1))))
K tuples:
F(z0, c(z1)) → c1(F(z0, s(f(z1, z1))), F(z1, z1))
Defined Rule Symbols:
f
Defined Pair Symbols:
F
Compound Symbols:
c1, c2
(5) CdtForwardInstantiationProof (BOTH BOUNDS(ID, ID) transformation)
Use forward instantiation to replace
F(
z0,
c(
z1)) →
c1(
F(
z0,
s(
f(
z1,
z1))),
F(
z1,
z1)) by
F(z0, c(c(y1))) → c1(F(z0, s(f(c(y1), c(y1)))), F(c(y1), c(y1)))
F(s(y0), c(z1)) → c1(F(s(y0), s(f(z1, z1))), F(z1, z1))
F(z0, c(s(y0))) → c1(F(z0, s(f(s(y0), s(y0)))), F(s(y0), s(y0)))
(6) Obligation:
Complexity Dependency Tuples Problem
Rules:
f(z0, c(z1)) → f(z0, s(f(z1, z1)))
f(s(z0), z1) → f(z0, s(c(z1)))
Tuples:
F(s(z0), z1) → c2(F(z0, s(c(z1))))
F(z0, c(c(y1))) → c1(F(z0, s(f(c(y1), c(y1)))), F(c(y1), c(y1)))
F(s(y0), c(z1)) → c1(F(s(y0), s(f(z1, z1))), F(z1, z1))
F(z0, c(s(y0))) → c1(F(z0, s(f(s(y0), s(y0)))), F(s(y0), s(y0)))
S tuples:
F(s(z0), z1) → c2(F(z0, s(c(z1))))
K tuples:
F(z0, c(c(y1))) → c1(F(z0, s(f(c(y1), c(y1)))), F(c(y1), c(y1)))
F(s(y0), c(z1)) → c1(F(s(y0), s(f(z1, z1))), F(z1, z1))
F(z0, c(s(y0))) → c1(F(z0, s(f(s(y0), s(y0)))), F(s(y0), s(y0)))
Defined Rule Symbols:
f
Defined Pair Symbols:
F
Compound Symbols:
c2, c1
(7) CdtGraphSplitRhsProof (BOTH BOUNDS(ID, ID) transformation)
Split RHS of tuples not part of any SCC
(8) Obligation:
Complexity Dependency Tuples Problem
Rules:
f(z0, c(z1)) → f(z0, s(f(z1, z1)))
f(s(z0), z1) → f(z0, s(c(z1)))
Tuples:
F(s(z0), z1) → c2(F(z0, s(c(z1))))
F(z0, c(c(y1))) → c1(F(z0, s(f(c(y1), c(y1)))), F(c(y1), c(y1)))
F(s(y0), c(z1)) → c3(F(s(y0), s(f(z1, z1))))
F(s(y0), c(z1)) → c3(F(z1, z1))
F(z0, c(s(y0))) → c3(F(z0, s(f(s(y0), s(y0)))))
F(z0, c(s(y0))) → c3(F(s(y0), s(y0)))
S tuples:
F(s(z0), z1) → c2(F(z0, s(c(z1))))
K tuples:
F(z0, c(c(y1))) → c1(F(z0, s(f(c(y1), c(y1)))), F(c(y1), c(y1)))
F(s(y0), c(z1)) → c3(F(s(y0), s(f(z1, z1))))
F(s(y0), c(z1)) → c3(F(z1, z1))
F(z0, c(s(y0))) → c3(F(z0, s(f(s(y0), s(y0)))))
F(z0, c(s(y0))) → c3(F(s(y0), s(y0)))
Defined Rule Symbols:
f
Defined Pair Symbols:
F
Compound Symbols:
c2, c1, c3
(9) CdtLeafRemovalProof (ComplexityIfPolyImplication transformation)
Removed 1 leading nodes:
F(s(y0), c(z1)) → c3(F(z1, z1))
(10) Obligation:
Complexity Dependency Tuples Problem
Rules:
f(z0, c(z1)) → f(z0, s(f(z1, z1)))
f(s(z0), z1) → f(z0, s(c(z1)))
Tuples:
F(s(z0), z1) → c2(F(z0, s(c(z1))))
F(z0, c(c(y1))) → c1(F(z0, s(f(c(y1), c(y1)))), F(c(y1), c(y1)))
F(s(y0), c(z1)) → c3(F(s(y0), s(f(z1, z1))))
F(z0, c(s(y0))) → c3(F(z0, s(f(s(y0), s(y0)))))
F(z0, c(s(y0))) → c3(F(s(y0), s(y0)))
S tuples:
F(s(z0), z1) → c2(F(z0, s(c(z1))))
K tuples:
F(z0, c(c(y1))) → c1(F(z0, s(f(c(y1), c(y1)))), F(c(y1), c(y1)))
F(s(y0), c(z1)) → c3(F(s(y0), s(f(z1, z1))))
F(z0, c(s(y0))) → c3(F(z0, s(f(s(y0), s(y0)))))
F(z0, c(s(y0))) → c3(F(s(y0), s(y0)))
Defined Rule Symbols:
f
Defined Pair Symbols:
F
Compound Symbols:
c2, c1, c3
(11) CdtNarrowingProof (BOTH BOUNDS(ID, ID) transformation)
Use narrowing to replace
F(
z0,
c(
c(
y1))) →
c1(
F(
z0,
s(
f(
c(
y1),
c(
y1)))),
F(
c(
y1),
c(
y1))) by
F(x0, c(c(z1))) → c1(F(x0, s(f(c(z1), s(f(z1, z1))))), F(c(z1), c(z1)))
(12) Obligation:
Complexity Dependency Tuples Problem
Rules:
f(z0, c(z1)) → f(z0, s(f(z1, z1)))
f(s(z0), z1) → f(z0, s(c(z1)))
Tuples:
F(s(z0), z1) → c2(F(z0, s(c(z1))))
F(s(y0), c(z1)) → c3(F(s(y0), s(f(z1, z1))))
F(z0, c(s(y0))) → c3(F(z0, s(f(s(y0), s(y0)))))
F(z0, c(s(y0))) → c3(F(s(y0), s(y0)))
F(x0, c(c(z1))) → c1(F(x0, s(f(c(z1), s(f(z1, z1))))), F(c(z1), c(z1)))
S tuples:
F(s(z0), z1) → c2(F(z0, s(c(z1))))
K tuples:
F(z0, c(c(y1))) → c1(F(z0, s(f(c(y1), c(y1)))), F(c(y1), c(y1)))
F(s(y0), c(z1)) → c3(F(s(y0), s(f(z1, z1))))
F(z0, c(s(y0))) → c3(F(z0, s(f(s(y0), s(y0)))))
F(z0, c(s(y0))) → c3(F(s(y0), s(y0)))
Defined Rule Symbols:
f
Defined Pair Symbols:
F
Compound Symbols:
c2, c3, c1
(13) CdtNarrowingProof (BOTH BOUNDS(ID, ID) transformation)
Use narrowing to replace
F(
z0,
c(
s(
y0))) →
c3(
F(
z0,
s(
f(
s(
y0),
s(
y0))))) by
F(x0, c(s(z0))) → c3(F(x0, s(f(z0, s(c(s(z0)))))))
(14) Obligation:
Complexity Dependency Tuples Problem
Rules:
f(z0, c(z1)) → f(z0, s(f(z1, z1)))
f(s(z0), z1) → f(z0, s(c(z1)))
Tuples:
F(s(z0), z1) → c2(F(z0, s(c(z1))))
F(s(y0), c(z1)) → c3(F(s(y0), s(f(z1, z1))))
F(z0, c(s(y0))) → c3(F(s(y0), s(y0)))
F(x0, c(c(z1))) → c1(F(x0, s(f(c(z1), s(f(z1, z1))))), F(c(z1), c(z1)))
F(x0, c(s(z0))) → c3(F(x0, s(f(z0, s(c(s(z0)))))))
S tuples:
F(s(z0), z1) → c2(F(z0, s(c(z1))))
K tuples:
F(z0, c(c(y1))) → c1(F(z0, s(f(c(y1), c(y1)))), F(c(y1), c(y1)))
F(s(y0), c(z1)) → c3(F(s(y0), s(f(z1, z1))))
F(z0, c(s(y0))) → c3(F(z0, s(f(s(y0), s(y0)))))
F(z0, c(s(y0))) → c3(F(s(y0), s(y0)))
Defined Rule Symbols:
f
Defined Pair Symbols:
F
Compound Symbols:
c2, c3, c1
(15) CdtInstantiationProof (BOTH BOUNDS(ID, ID) transformation)
Use instantiation to replace
F(
s(
z0),
z1) →
c2(
F(
z0,
s(
c(
z1)))) by
F(s(z0), s(c(x1))) → c2(F(z0, s(c(s(c(x1))))))
F(s(x0), s(y0)) → c2(F(x0, s(c(s(y0)))))
F(s(x1), s(x1)) → c2(F(x1, s(c(s(x1)))))
F(s(z0), s(f(c(x1), s(y0)))) → c2(F(z0, s(c(s(f(c(x1), s(y0)))))))
F1(s(z0), z1) → c2(F(z0, s(c(z1))))
(16) Obligation:
Complexity Dependency Tuples Problem
Rules:
f(z0, c(z1)) → f(z0, s(f(z1, z1)))
f(s(z0), z1) → f(z0, s(c(z1)))
Tuples:
F(s(y0), c(z1)) → c3(F(s(y0), s(f(z1, z1))))
F(z0, c(s(y0))) → c3(F(s(y0), s(y0)))
F(x0, c(c(z1))) → c1(F(x0, s(f(c(z1), s(f(z1, z1))))), F(c(z1), c(z1)))
F(x0, c(s(z0))) → c3(F(x0, s(f(z0, s(c(s(z0)))))))
F(s(z0), s(c(x1))) → c2(F(z0, s(c(s(c(x1))))))
F(s(x0), s(y0)) → c2(F(x0, s(c(s(y0)))))
F(s(x1), s(x1)) → c2(F(x1, s(c(s(x1)))))
F(s(z0), s(f(c(x1), s(y0)))) → c2(F(z0, s(c(s(f(c(x1), s(y0)))))))
F1(s(z0), z1) → c2(F(z0, s(c(z1))))
S tuples:
F(s(z0), s(c(x1))) → c2(F(z0, s(c(s(c(x1))))))
F(s(x0), s(y0)) → c2(F(x0, s(c(s(y0)))))
F(s(x1), s(x1)) → c2(F(x1, s(c(s(x1)))))
F(s(z0), s(f(c(x1), s(y0)))) → c2(F(z0, s(c(s(f(c(x1), s(y0)))))))
F1(s(z0), z1) → c2(F(z0, s(c(z1))))
K tuples:
F(z0, c(c(y1))) → c1(F(z0, s(f(c(y1), c(y1)))), F(c(y1), c(y1)))
F(s(y0), c(z1)) → c3(F(s(y0), s(f(z1, z1))))
F(z0, c(s(y0))) → c3(F(z0, s(f(s(y0), s(y0)))))
F(z0, c(s(y0))) → c3(F(s(y0), s(y0)))
Defined Rule Symbols:
f
Defined Pair Symbols:
F, F1
Compound Symbols:
c3, c1, c2
(17) CdtLeafRemovalProof (ComplexityIfPolyImplication transformation)
Removed 1 leading nodes:
F1(s(z0), z1) → c2(F(z0, s(c(z1))))
(18) Obligation:
Complexity Dependency Tuples Problem
Rules:
f(z0, c(z1)) → f(z0, s(f(z1, z1)))
f(s(z0), z1) → f(z0, s(c(z1)))
Tuples:
F(s(y0), c(z1)) → c3(F(s(y0), s(f(z1, z1))))
F(z0, c(s(y0))) → c3(F(s(y0), s(y0)))
F(x0, c(c(z1))) → c1(F(x0, s(f(c(z1), s(f(z1, z1))))), F(c(z1), c(z1)))
F(x0, c(s(z0))) → c3(F(x0, s(f(z0, s(c(s(z0)))))))
F(s(z0), s(c(x1))) → c2(F(z0, s(c(s(c(x1))))))
F(s(x0), s(y0)) → c2(F(x0, s(c(s(y0)))))
F(s(x1), s(x1)) → c2(F(x1, s(c(s(x1)))))
F(s(z0), s(f(c(x1), s(y0)))) → c2(F(z0, s(c(s(f(c(x1), s(y0)))))))
S tuples:
F(s(z0), s(c(x1))) → c2(F(z0, s(c(s(c(x1))))))
F(s(x0), s(y0)) → c2(F(x0, s(c(s(y0)))))
F(s(x1), s(x1)) → c2(F(x1, s(c(s(x1)))))
F(s(z0), s(f(c(x1), s(y0)))) → c2(F(z0, s(c(s(f(c(x1), s(y0)))))))
K tuples:
F(s(y0), c(z1)) → c3(F(s(y0), s(f(z1, z1))))
F(z0, c(s(y0))) → c3(F(s(y0), s(y0)))
Defined Rule Symbols:
f
Defined Pair Symbols:
F
Compound Symbols:
c3, c1, c2
(19) CdtInstantiationProof (BOTH BOUNDS(ID, ID) transformation)
Use instantiation to replace
F(
z0,
c(
s(
y0))) →
c3(
F(
s(
y0),
s(
y0))) by
F(c(s(z1)), c(s(z1))) → c3(F(s(z1), s(z1)))
(20) Obligation:
Complexity Dependency Tuples Problem
Rules:
f(z0, c(z1)) → f(z0, s(f(z1, z1)))
f(s(z0), z1) → f(z0, s(c(z1)))
Tuples:
F(s(y0), c(z1)) → c3(F(s(y0), s(f(z1, z1))))
F(x0, c(c(z1))) → c1(F(x0, s(f(c(z1), s(f(z1, z1))))), F(c(z1), c(z1)))
F(x0, c(s(z0))) → c3(F(x0, s(f(z0, s(c(s(z0)))))))
F(s(z0), s(c(x1))) → c2(F(z0, s(c(s(c(x1))))))
F(s(x0), s(y0)) → c2(F(x0, s(c(s(y0)))))
F(s(x1), s(x1)) → c2(F(x1, s(c(s(x1)))))
F(s(z0), s(f(c(x1), s(y0)))) → c2(F(z0, s(c(s(f(c(x1), s(y0)))))))
F(c(s(z1)), c(s(z1))) → c3(F(s(z1), s(z1)))
S tuples:
F(s(z0), s(c(x1))) → c2(F(z0, s(c(s(c(x1))))))
F(s(x0), s(y0)) → c2(F(x0, s(c(s(y0)))))
F(s(x1), s(x1)) → c2(F(x1, s(c(s(x1)))))
F(s(z0), s(f(c(x1), s(y0)))) → c2(F(z0, s(c(s(f(c(x1), s(y0)))))))
K tuples:
F(s(y0), c(z1)) → c3(F(s(y0), s(f(z1, z1))))
F(c(s(z1)), c(s(z1))) → c3(F(s(z1), s(z1)))
Defined Rule Symbols:
f
Defined Pair Symbols:
F
Compound Symbols:
c3, c1, c2
(21) CdtInstantiationProof (BOTH BOUNDS(ID, ID) transformation)
Use instantiation to replace
F(
x0,
c(
c(
z1))) →
c1(
F(
x0,
s(
f(
c(
z1),
s(
f(
z1,
z1))))),
F(
c(
z1),
c(
z1))) by
F(c(c(z1)), c(c(z1))) → c1(F(c(c(z1)), s(f(c(z1), s(f(z1, z1))))), F(c(z1), c(z1)))
(22) Obligation:
Complexity Dependency Tuples Problem
Rules:
f(z0, c(z1)) → f(z0, s(f(z1, z1)))
f(s(z0), z1) → f(z0, s(c(z1)))
Tuples:
F(s(y0), c(z1)) → c3(F(s(y0), s(f(z1, z1))))
F(x0, c(s(z0))) → c3(F(x0, s(f(z0, s(c(s(z0)))))))
F(s(z0), s(c(x1))) → c2(F(z0, s(c(s(c(x1))))))
F(s(x0), s(y0)) → c2(F(x0, s(c(s(y0)))))
F(s(x1), s(x1)) → c2(F(x1, s(c(s(x1)))))
F(s(z0), s(f(c(x1), s(y0)))) → c2(F(z0, s(c(s(f(c(x1), s(y0)))))))
F(c(s(z1)), c(s(z1))) → c3(F(s(z1), s(z1)))
F(c(c(z1)), c(c(z1))) → c1(F(c(c(z1)), s(f(c(z1), s(f(z1, z1))))), F(c(z1), c(z1)))
S tuples:
F(s(z0), s(c(x1))) → c2(F(z0, s(c(s(c(x1))))))
F(s(x0), s(y0)) → c2(F(x0, s(c(s(y0)))))
F(s(x1), s(x1)) → c2(F(x1, s(c(s(x1)))))
F(s(z0), s(f(c(x1), s(y0)))) → c2(F(z0, s(c(s(f(c(x1), s(y0)))))))
K tuples:
F(s(y0), c(z1)) → c3(F(s(y0), s(f(z1, z1))))
F(c(s(z1)), c(s(z1))) → c3(F(s(z1), s(z1)))
Defined Rule Symbols:
f
Defined Pair Symbols:
F
Compound Symbols:
c3, c2, c1
(23) CdtRhsSimplificationProcessorProof (BOTH BOUNDS(ID, ID) transformation)
Removed 1 trailing tuple parts
(24) Obligation:
Complexity Dependency Tuples Problem
Rules:
f(z0, c(z1)) → f(z0, s(f(z1, z1)))
f(s(z0), z1) → f(z0, s(c(z1)))
Tuples:
F(s(y0), c(z1)) → c3(F(s(y0), s(f(z1, z1))))
F(x0, c(s(z0))) → c3(F(x0, s(f(z0, s(c(s(z0)))))))
F(s(z0), s(c(x1))) → c2(F(z0, s(c(s(c(x1))))))
F(s(x0), s(y0)) → c2(F(x0, s(c(s(y0)))))
F(s(x1), s(x1)) → c2(F(x1, s(c(s(x1)))))
F(s(z0), s(f(c(x1), s(y0)))) → c2(F(z0, s(c(s(f(c(x1), s(y0)))))))
F(c(s(z1)), c(s(z1))) → c3(F(s(z1), s(z1)))
F(c(c(z1)), c(c(z1))) → c1(F(c(z1), c(z1)))
S tuples:
F(s(z0), s(c(x1))) → c2(F(z0, s(c(s(c(x1))))))
F(s(x0), s(y0)) → c2(F(x0, s(c(s(y0)))))
F(s(x1), s(x1)) → c2(F(x1, s(c(s(x1)))))
F(s(z0), s(f(c(x1), s(y0)))) → c2(F(z0, s(c(s(f(c(x1), s(y0)))))))
K tuples:
F(s(y0), c(z1)) → c3(F(s(y0), s(f(z1, z1))))
F(c(s(z1)), c(s(z1))) → c3(F(s(z1), s(z1)))
Defined Rule Symbols:
f
Defined Pair Symbols:
F
Compound Symbols:
c3, c2, c1
(25) CdtRuleRemovalProof (UPPER BOUND(ADD(n^1)) transformation)
Found a reduction pair which oriented the following tuples strictly. Hence they can be removed from S.
F(s(z0), s(c(x1))) → c2(F(z0, s(c(s(c(x1))))))
F(s(x0), s(y0)) → c2(F(x0, s(c(s(y0)))))
F(s(x1), s(x1)) → c2(F(x1, s(c(s(x1)))))
F(s(z0), s(f(c(x1), s(y0)))) → c2(F(z0, s(c(s(f(c(x1), s(y0)))))))
We considered the (Usable) Rules:none
And the Tuples:
F(s(y0), c(z1)) → c3(F(s(y0), s(f(z1, z1))))
F(x0, c(s(z0))) → c3(F(x0, s(f(z0, s(c(s(z0)))))))
F(s(z0), s(c(x1))) → c2(F(z0, s(c(s(c(x1))))))
F(s(x0), s(y0)) → c2(F(x0, s(c(s(y0)))))
F(s(x1), s(x1)) → c2(F(x1, s(c(s(x1)))))
F(s(z0), s(f(c(x1), s(y0)))) → c2(F(z0, s(c(s(f(c(x1), s(y0)))))))
F(c(s(z1)), c(s(z1))) → c3(F(s(z1), s(z1)))
F(c(c(z1)), c(c(z1))) → c1(F(c(z1), c(z1)))
The order we found is given by the following interpretation:
Polynomial interpretation :
POL(F(x1, x2)) = x1
POL(c(x1)) = x1
POL(c1(x1)) = x1
POL(c2(x1)) = x1
POL(c3(x1)) = x1
POL(f(x1, x2)) = 0
POL(s(x1)) = [1] + x1
(26) Obligation:
Complexity Dependency Tuples Problem
Rules:
f(z0, c(z1)) → f(z0, s(f(z1, z1)))
f(s(z0), z1) → f(z0, s(c(z1)))
Tuples:
F(s(y0), c(z1)) → c3(F(s(y0), s(f(z1, z1))))
F(x0, c(s(z0))) → c3(F(x0, s(f(z0, s(c(s(z0)))))))
F(s(z0), s(c(x1))) → c2(F(z0, s(c(s(c(x1))))))
F(s(x0), s(y0)) → c2(F(x0, s(c(s(y0)))))
F(s(x1), s(x1)) → c2(F(x1, s(c(s(x1)))))
F(s(z0), s(f(c(x1), s(y0)))) → c2(F(z0, s(c(s(f(c(x1), s(y0)))))))
F(c(s(z1)), c(s(z1))) → c3(F(s(z1), s(z1)))
F(c(c(z1)), c(c(z1))) → c1(F(c(z1), c(z1)))
S tuples:none
K tuples:
F(s(y0), c(z1)) → c3(F(s(y0), s(f(z1, z1))))
F(c(s(z1)), c(s(z1))) → c3(F(s(z1), s(z1)))
F(s(z0), s(c(x1))) → c2(F(z0, s(c(s(c(x1))))))
F(s(x0), s(y0)) → c2(F(x0, s(c(s(y0)))))
F(s(x1), s(x1)) → c2(F(x1, s(c(s(x1)))))
F(s(z0), s(f(c(x1), s(y0)))) → c2(F(z0, s(c(s(f(c(x1), s(y0)))))))
Defined Rule Symbols:
f
Defined Pair Symbols:
F
Compound Symbols:
c3, c2, c1
(27) SIsEmptyProof (BOTH BOUNDS(ID, ID) transformation)
The set S is empty
(28) BOUNDS(1, 1)