<s>
In	O
mathematical	O
analysis	O
and	O
metric	O
geometry	O
,	O
Laakso	B-Algorithm
spaces	I-Algorithm
are	O
a	O
class	O
of	O
metric	O
spaces	O
which	O
are	O
fractal	B-Application
,	O
in	O
the	O
sense	O
that	O
they	O
have	O
non-integer	O
Hausdorff	O
dimension	O
,	O
but	O
that	O
admit	O
a	O
notion	O
of	O
differential	O
calculus	O
.	O
</s>
<s>
Cheeger	O
defined	O
a	O
notion	O
of	O
differentiability	O
for	O
real-valued	O
functions	O
on	O
metric	O
measure	O
spaces	O
which	O
are	O
doubling	O
and	O
satisfy	O
a	O
Poincaré	O
inequality	O
,	O
generalizing	O
the	O
usual	O
notion	O
on	O
Euclidean	O
space	O
and	O
Riemannian	B-Architecture
manifolds	I-Architecture
.	O
</s>
<s>
Spaces	O
that	O
satisfy	O
these	O
conditions	O
include	O
Carnot	O
groups	O
and	O
other	O
sub-Riemannian	O
manifolds	O
,	O
but	O
not	O
classic	O
fractals	B-Application
such	O
as	O
the	O
Koch	B-Algorithm
snowflake	I-Algorithm
or	O
the	O
Sierpiński	O
gasket	O
.	O
</s>
<s>
These	O
examples	O
are	O
now	O
known	O
as	O
Laakso	B-Algorithm
spaces	I-Algorithm
.	O
</s>
