R
↳Dependency Pair Analysis
REV1(X, cons(Y, L)) -> REV1(Y, L)
REV(cons(X, L)) -> REV1(X, L)
REV(cons(X, L)) -> REV2(X, L)
REV2(X, cons(Y, L)) -> REV(cons(X, rev(rev2(Y, L))))
REV2(X, cons(Y, L)) -> REV(rev2(Y, L))
REV2(X, cons(Y, L)) -> REV2(Y, L)
R
↳DPs
→DP Problem 1
↳Forward Instantiation Transformation
→DP Problem 2
↳Nar
REV1(X, cons(Y, L)) -> REV1(Y, L)
rev1(0, nil) -> 0
rev1(s(X), nil) -> s(X)
rev1(X, cons(Y, L)) -> rev1(Y, L)
rev(nil) -> nil
rev(cons(X, L)) -> cons(rev1(X, L), rev2(X, L))
rev2(X, nil) -> nil
rev2(X, cons(Y, L)) -> rev(cons(X, rev(rev2(Y, L))))
innermost
one new Dependency Pair is created:
REV1(X, cons(Y, L)) -> REV1(Y, L)
REV1(X, cons(Y0, cons(Y'', L''))) -> REV1(Y0, cons(Y'', L''))
R
↳DPs
→DP Problem 1
↳FwdInst
→DP Problem 3
↳Forward Instantiation Transformation
→DP Problem 2
↳Nar
REV1(X, cons(Y0, cons(Y'', L''))) -> REV1(Y0, cons(Y'', L''))
rev1(0, nil) -> 0
rev1(s(X), nil) -> s(X)
rev1(X, cons(Y, L)) -> rev1(Y, L)
rev(nil) -> nil
rev(cons(X, L)) -> cons(rev1(X, L), rev2(X, L))
rev2(X, nil) -> nil
rev2(X, cons(Y, L)) -> rev(cons(X, rev(rev2(Y, L))))
innermost
one new Dependency Pair is created:
REV1(X, cons(Y0, cons(Y'', L''))) -> REV1(Y0, cons(Y'', L''))
REV1(X, cons(Y0'', cons(Y''0, cons(Y'''', L'''')))) -> REV1(Y0'', cons(Y''0, cons(Y'''', L'''')))
R
↳DPs
→DP Problem 1
↳FwdInst
→DP Problem 3
↳FwdInst
...
→DP Problem 4
↳Argument Filtering and Ordering
→DP Problem 2
↳Nar
REV1(X, cons(Y0'', cons(Y''0, cons(Y'''', L'''')))) -> REV1(Y0'', cons(Y''0, cons(Y'''', L'''')))
rev1(0, nil) -> 0
rev1(s(X), nil) -> s(X)
rev1(X, cons(Y, L)) -> rev1(Y, L)
rev(nil) -> nil
rev(cons(X, L)) -> cons(rev1(X, L), rev2(X, L))
rev2(X, nil) -> nil
rev2(X, cons(Y, L)) -> rev(cons(X, rev(rev2(Y, L))))
innermost
REV1(X, cons(Y0'', cons(Y''0, cons(Y'''', L'''')))) -> REV1(Y0'', cons(Y''0, cons(Y'''', L'''')))
REV1(x1, x2) -> x2
cons(x1, x2) -> cons(x1, x2)
R
↳DPs
→DP Problem 1
↳FwdInst
→DP Problem 3
↳FwdInst
...
→DP Problem 5
↳Dependency Graph
→DP Problem 2
↳Nar
rev1(0, nil) -> 0
rev1(s(X), nil) -> s(X)
rev1(X, cons(Y, L)) -> rev1(Y, L)
rev(nil) -> nil
rev(cons(X, L)) -> cons(rev1(X, L), rev2(X, L))
rev2(X, nil) -> nil
rev2(X, cons(Y, L)) -> rev(cons(X, rev(rev2(Y, L))))
innermost
R
↳DPs
→DP Problem 1
↳FwdInst
→DP Problem 2
↳Narrowing Transformation
REV2(X, cons(Y, L)) -> REV2(Y, L)
REV2(X, cons(Y, L)) -> REV(rev2(Y, L))
REV2(X, cons(Y, L)) -> REV(cons(X, rev(rev2(Y, L))))
REV(cons(X, L)) -> REV2(X, L)
rev1(0, nil) -> 0
rev1(s(X), nil) -> s(X)
rev1(X, cons(Y, L)) -> rev1(Y, L)
rev(nil) -> nil
rev(cons(X, L)) -> cons(rev1(X, L), rev2(X, L))
rev2(X, nil) -> nil
rev2(X, cons(Y, L)) -> rev(cons(X, rev(rev2(Y, L))))
innermost
two new Dependency Pairs are created:
REV2(X, cons(Y, L)) -> REV(rev2(Y, L))
REV2(X, cons(Y', nil)) -> REV(nil)
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(rev(cons(Y0, rev(rev2(Y'', L'')))))
R
↳DPs
→DP Problem 1
↳FwdInst
→DP Problem 2
↳Nar
→DP Problem 6
↳Rewriting Transformation
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(rev(cons(Y0, rev(rev2(Y'', L'')))))
REV(cons(X, L)) -> REV2(X, L)
REV2(X, cons(Y, L)) -> REV(cons(X, rev(rev2(Y, L))))
REV2(X, cons(Y, L)) -> REV2(Y, L)
rev1(0, nil) -> 0
rev1(s(X), nil) -> s(X)
rev1(X, cons(Y, L)) -> rev1(Y, L)
rev(nil) -> nil
rev(cons(X, L)) -> cons(rev1(X, L), rev2(X, L))
rev2(X, nil) -> nil
rev2(X, cons(Y, L)) -> rev(cons(X, rev(rev2(Y, L))))
innermost
one new Dependency Pair is created:
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(rev(cons(Y0, rev(rev2(Y'', L'')))))
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(cons(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))))
R
↳DPs
→DP Problem 1
↳FwdInst
→DP Problem 2
↳Nar
→DP Problem 6
↳Rw
...
→DP Problem 7
↳Forward Instantiation Transformation
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(cons(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))))
REV2(X, cons(Y, L)) -> REV2(Y, L)
REV2(X, cons(Y, L)) -> REV(cons(X, rev(rev2(Y, L))))
REV(cons(X, L)) -> REV2(X, L)
rev1(0, nil) -> 0
rev1(s(X), nil) -> s(X)
rev1(X, cons(Y, L)) -> rev1(Y, L)
rev(nil) -> nil
rev(cons(X, L)) -> cons(rev1(X, L), rev2(X, L))
rev2(X, nil) -> nil
rev2(X, cons(Y, L)) -> rev(cons(X, rev(rev2(Y, L))))
innermost
two new Dependency Pairs are created:
REV(cons(X, L)) -> REV2(X, L)
REV(cons(X'', cons(Y'', L''))) -> REV2(X'', cons(Y'', L''))
REV(cons(X'', cons(Y0'', cons(Y'''', L'''')))) -> REV2(X'', cons(Y0'', cons(Y'''', L'''')))
R
↳DPs
→DP Problem 1
↳FwdInst
→DP Problem 2
↳Nar
→DP Problem 6
↳Rw
...
→DP Problem 8
↳Narrowing Transformation
REV2(X, cons(Y, L)) -> REV2(Y, L)
REV(cons(X'', cons(Y0'', cons(Y'''', L'''')))) -> REV2(X'', cons(Y0'', cons(Y'''', L'''')))
REV2(X, cons(Y, L)) -> REV(cons(X, rev(rev2(Y, L))))
REV(cons(X'', cons(Y'', L''))) -> REV2(X'', cons(Y'', L''))
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(cons(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))))
rev1(0, nil) -> 0
rev1(s(X), nil) -> s(X)
rev1(X, cons(Y, L)) -> rev1(Y, L)
rev(nil) -> nil
rev(cons(X, L)) -> cons(rev1(X, L), rev2(X, L))
rev2(X, nil) -> nil
rev2(X, cons(Y, L)) -> rev(cons(X, rev(rev2(Y, L))))
innermost
two new Dependency Pairs are created:
REV2(X, cons(Y, L)) -> REV(cons(X, rev(rev2(Y, L))))
REV2(X, cons(Y', nil)) -> REV(cons(X, rev(nil)))
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(cons(X, rev(rev(cons(Y0, rev(rev2(Y'', L'')))))))
R
↳DPs
→DP Problem 1
↳FwdInst
→DP Problem 2
↳Nar
→DP Problem 6
↳Rw
...
→DP Problem 9
↳Rewriting Transformation
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(cons(X, rev(rev(cons(Y0, rev(rev2(Y'', L'')))))))
REV(cons(X'', cons(Y0'', cons(Y'''', L'''')))) -> REV2(X'', cons(Y0'', cons(Y'''', L'''')))
REV2(X, cons(Y', nil)) -> REV(cons(X, rev(nil)))
REV(cons(X'', cons(Y'', L''))) -> REV2(X'', cons(Y'', L''))
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(cons(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))))
REV2(X, cons(Y, L)) -> REV2(Y, L)
rev1(0, nil) -> 0
rev1(s(X), nil) -> s(X)
rev1(X, cons(Y, L)) -> rev1(Y, L)
rev(nil) -> nil
rev(cons(X, L)) -> cons(rev1(X, L), rev2(X, L))
rev2(X, nil) -> nil
rev2(X, cons(Y, L)) -> rev(cons(X, rev(rev2(Y, L))))
innermost
one new Dependency Pair is created:
REV2(X, cons(Y', nil)) -> REV(cons(X, rev(nil)))
REV2(X, cons(Y', nil)) -> REV(cons(X, nil))
R
↳DPs
→DP Problem 1
↳FwdInst
→DP Problem 2
↳Nar
→DP Problem 6
↳Rw
...
→DP Problem 10
↳Rewriting Transformation
REV(cons(X'', cons(Y0'', cons(Y'''', L'''')))) -> REV2(X'', cons(Y0'', cons(Y'''', L'''')))
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(cons(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))))
REV2(X, cons(Y, L)) -> REV2(Y, L)
REV(cons(X'', cons(Y'', L''))) -> REV2(X'', cons(Y'', L''))
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(cons(X, rev(rev(cons(Y0, rev(rev2(Y'', L'')))))))
rev1(0, nil) -> 0
rev1(s(X), nil) -> s(X)
rev1(X, cons(Y, L)) -> rev1(Y, L)
rev(nil) -> nil
rev(cons(X, L)) -> cons(rev1(X, L), rev2(X, L))
rev2(X, nil) -> nil
rev2(X, cons(Y, L)) -> rev(cons(X, rev(rev2(Y, L))))
innermost
one new Dependency Pair is created:
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(cons(X, rev(rev(cons(Y0, rev(rev2(Y'', L'')))))))
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(cons(X, rev(cons(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))))))
R
↳DPs
→DP Problem 1
↳FwdInst
→DP Problem 2
↳Nar
→DP Problem 6
↳Rw
...
→DP Problem 11
↳Rewriting Transformation
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(cons(X, rev(cons(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))))))
REV(cons(X'', cons(Y'', L''))) -> REV2(X'', cons(Y'', L''))
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(cons(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))))
REV2(X, cons(Y, L)) -> REV2(Y, L)
REV(cons(X'', cons(Y0'', cons(Y'''', L'''')))) -> REV2(X'', cons(Y0'', cons(Y'''', L'''')))
rev1(0, nil) -> 0
rev1(s(X), nil) -> s(X)
rev1(X, cons(Y, L)) -> rev1(Y, L)
rev(nil) -> nil
rev(cons(X, L)) -> cons(rev1(X, L), rev2(X, L))
rev2(X, nil) -> nil
rev2(X, cons(Y, L)) -> rev(cons(X, rev(rev2(Y, L))))
innermost
one new Dependency Pair is created:
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(cons(X, rev(cons(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))))))
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(cons(X, cons(rev1(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))), rev2(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))))))
R
↳DPs
→DP Problem 1
↳FwdInst
→DP Problem 2
↳Nar
→DP Problem 6
↳Rw
...
→DP Problem 12
↳Forward Instantiation Transformation
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(cons(X, cons(rev1(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))), rev2(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))))))
REV(cons(X'', cons(Y0'', cons(Y'''', L'''')))) -> REV2(X'', cons(Y0'', cons(Y'''', L'''')))
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(cons(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))))
REV2(X, cons(Y, L)) -> REV2(Y, L)
REV(cons(X'', cons(Y'', L''))) -> REV2(X'', cons(Y'', L''))
rev1(0, nil) -> 0
rev1(s(X), nil) -> s(X)
rev1(X, cons(Y, L)) -> rev1(Y, L)
rev(nil) -> nil
rev(cons(X, L)) -> cons(rev1(X, L), rev2(X, L))
rev2(X, nil) -> nil
rev2(X, cons(Y, L)) -> rev(cons(X, rev(rev2(Y, L))))
innermost
two new Dependency Pairs are created:
REV2(X, cons(Y, L)) -> REV2(Y, L)
REV2(X, cons(Y0, cons(Y'', L''))) -> REV2(Y0, cons(Y'', L''))
REV2(X, cons(Y', cons(Y0'', cons(Y'''', L'''')))) -> REV2(Y', cons(Y0'', cons(Y'''', L'''')))
R
↳DPs
→DP Problem 1
↳FwdInst
→DP Problem 2
↳Nar
→DP Problem 6
↳Rw
...
→DP Problem 13
↳Forward Instantiation Transformation
REV2(X, cons(Y', cons(Y0'', cons(Y'''', L'''')))) -> REV2(Y', cons(Y0'', cons(Y'''', L'''')))
REV2(X, cons(Y0, cons(Y'', L''))) -> REV2(Y0, cons(Y'', L''))
REV(cons(X'', cons(Y0'', cons(Y'''', L'''')))) -> REV2(X'', cons(Y0'', cons(Y'''', L'''')))
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(cons(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))))
REV(cons(X'', cons(Y'', L''))) -> REV2(X'', cons(Y'', L''))
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(cons(X, cons(rev1(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))), rev2(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))))))
rev1(0, nil) -> 0
rev1(s(X), nil) -> s(X)
rev1(X, cons(Y, L)) -> rev1(Y, L)
rev(nil) -> nil
rev(cons(X, L)) -> cons(rev1(X, L), rev2(X, L))
rev2(X, nil) -> nil
rev2(X, cons(Y, L)) -> rev(cons(X, rev(rev2(Y, L))))
innermost
two new Dependency Pairs are created:
REV(cons(X'', cons(Y'', L''))) -> REV2(X'', cons(Y'', L''))
REV(cons(X''', cons(Y''0, cons(Y'''', L'''')))) -> REV2(X''', cons(Y''0, cons(Y'''', L'''')))
REV(cons(X''', cons(Y'''', cons(Y0'''', cons(Y'''''', L''''''))))) -> REV2(X''', cons(Y'''', cons(Y0'''', cons(Y'''''', L''''''))))
R
↳DPs
→DP Problem 1
↳FwdInst
→DP Problem 2
↳Nar
→DP Problem 6
↳Rw
...
→DP Problem 14
↳Forward Instantiation Transformation
REV(cons(X''', cons(Y'''', cons(Y0'''', cons(Y'''''', L''''''))))) -> REV2(X''', cons(Y'''', cons(Y0'''', cons(Y'''''', L''''''))))
REV2(X, cons(Y0, cons(Y'', L''))) -> REV2(Y0, cons(Y'', L''))
REV(cons(X''', cons(Y''0, cons(Y'''', L'''')))) -> REV2(X''', cons(Y''0, cons(Y'''', L'''')))
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(cons(X, cons(rev1(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))), rev2(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))))))
REV(cons(X'', cons(Y0'', cons(Y'''', L'''')))) -> REV2(X'', cons(Y0'', cons(Y'''', L'''')))
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(cons(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))))
REV2(X, cons(Y', cons(Y0'', cons(Y'''', L'''')))) -> REV2(Y', cons(Y0'', cons(Y'''', L'''')))
rev1(0, nil) -> 0
rev1(s(X), nil) -> s(X)
rev1(X, cons(Y, L)) -> rev1(Y, L)
rev(nil) -> nil
rev(cons(X, L)) -> cons(rev1(X, L), rev2(X, L))
rev2(X, nil) -> nil
rev2(X, cons(Y, L)) -> rev(cons(X, rev(rev2(Y, L))))
innermost
two new Dependency Pairs are created:
REV2(X, cons(Y0, cons(Y'', L''))) -> REV2(Y0, cons(Y'', L''))
REV2(X, cons(Y0'', cons(Y''0, cons(Y'''', L'''')))) -> REV2(Y0'', cons(Y''0, cons(Y'''', L'''')))
REV2(X, cons(Y0', cons(Y'''', cons(Y0'''', cons(Y'''''', L''''''))))) -> REV2(Y0', cons(Y'''', cons(Y0'''', cons(Y'''''', L''''''))))
R
↳DPs
→DP Problem 1
↳FwdInst
→DP Problem 2
↳Nar
→DP Problem 6
↳Rw
...
→DP Problem 15
↳Argument Filtering and Ordering
REV2(X, cons(Y0', cons(Y'''', cons(Y0'''', cons(Y'''''', L''''''))))) -> REV2(Y0', cons(Y'''', cons(Y0'''', cons(Y'''''', L''''''))))
REV2(X, cons(Y0'', cons(Y''0, cons(Y'''', L'''')))) -> REV2(Y0'', cons(Y''0, cons(Y'''', L'''')))
REV2(X, cons(Y', cons(Y0'', cons(Y'''', L'''')))) -> REV2(Y', cons(Y0'', cons(Y'''', L'''')))
REV(cons(X''', cons(Y''0, cons(Y'''', L'''')))) -> REV2(X''', cons(Y''0, cons(Y'''', L'''')))
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(cons(X, cons(rev1(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))), rev2(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))))))
REV(cons(X'', cons(Y0'', cons(Y'''', L'''')))) -> REV2(X'', cons(Y0'', cons(Y'''', L'''')))
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(cons(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))))
REV(cons(X''', cons(Y'''', cons(Y0'''', cons(Y'''''', L''''''))))) -> REV2(X''', cons(Y'''', cons(Y0'''', cons(Y'''''', L''''''))))
rev1(0, nil) -> 0
rev1(s(X), nil) -> s(X)
rev1(X, cons(Y, L)) -> rev1(Y, L)
rev(nil) -> nil
rev(cons(X, L)) -> cons(rev1(X, L), rev2(X, L))
rev2(X, nil) -> nil
rev2(X, cons(Y, L)) -> rev(cons(X, rev(rev2(Y, L))))
innermost
REV2(X, cons(Y0', cons(Y'''', cons(Y0'''', cons(Y'''''', L''''''))))) -> REV2(Y0', cons(Y'''', cons(Y0'''', cons(Y'''''', L''''''))))
REV2(X, cons(Y0'', cons(Y''0, cons(Y'''', L'''')))) -> REV2(Y0'', cons(Y''0, cons(Y'''', L'''')))
REV2(X, cons(Y', cons(Y0'', cons(Y'''', L'''')))) -> REV2(Y', cons(Y0'', cons(Y'''', L'''')))
REV(cons(X''', cons(Y''0, cons(Y'''', L'''')))) -> REV2(X''', cons(Y''0, cons(Y'''', L'''')))
REV(cons(X'', cons(Y0'', cons(Y'''', L'''')))) -> REV2(X'', cons(Y0'', cons(Y'''', L'''')))
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(cons(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))))
REV(cons(X''', cons(Y'''', cons(Y0'''', cons(Y'''''', L''''''))))) -> REV2(X''', cons(Y'''', cons(Y0'''', cons(Y'''''', L''''''))))
rev2(X, nil) -> nil
rev2(X, cons(Y, L)) -> rev(cons(X, rev(rev2(Y, L))))
rev(nil) -> nil
rev(cons(X, L)) -> cons(rev1(X, L), rev2(X, L))
REV(x1) -> x1
cons(x1, x2) -> cons(x2)
REV2(x1, x2) -> x2
rev2(x1, x2) -> x2
rev(x1) -> x1
R
↳DPs
→DP Problem 1
↳FwdInst
→DP Problem 2
↳Nar
→DP Problem 6
↳Rw
...
→DP Problem 16
↳Dependency Graph
REV2(X, cons(Y0, cons(Y'', L''))) -> REV(cons(X, cons(rev1(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))), rev2(rev1(Y0, rev(rev2(Y'', L''))), rev2(Y0, rev(rev2(Y'', L'')))))))
rev1(0, nil) -> 0
rev1(s(X), nil) -> s(X)
rev1(X, cons(Y, L)) -> rev1(Y, L)
rev(nil) -> nil
rev(cons(X, L)) -> cons(rev1(X, L), rev2(X, L))
rev2(X, nil) -> nil
rev2(X, cons(Y, L)) -> rev(cons(X, rev(rev2(Y, L))))
innermost