Space-Efficient Circuit Evaluation
  We prove that uniform circuits of size n can be evaluated in space O(n/log n). Thus, Space(O(n)) is not in uniform Size(o(n*log n)). For uniformity, we only require that the circuit is O(n/log n)-Space uniform. We also generalize the construction to prove that a machine with O(n^delta) (delta<1) internal storage and O(2^n^delta) length single-bit-access read-write RAM that does only O(n) RAM reads (1 bit per read) can be simulated in space O(n * log log n / log n). 
Dmytro Taranovsky
cs.CC