lte
Cons
x'
xs'
Cons
x
xs
lte
xs'
xs
lte
Cons
x
xs
Nil
False
even
Cons
x
Nil
False
even
Cons
x'
Cons
x
xs
even
xs
notEmpty
Cons
x
xs
True
notEmpty
Nil
False
lte
Nil
y
True
even
Nil
True
goal
x
y
and
lte
x
y
even
x
and
False
False
False
and
True
False
False
and
False
True
False
and
True
True
True
even
1
lte
2
True
0
Cons
2
Nil
0
notEmpty
1
and
2
goal
2
False
0
INNERMOST