A simple linear space algorithm for computing a longest common   increasing subsequence
  This paper reformulates the problem of finding a longest common increasing subsequence of the two given input sequences in a very succinct way. An extremely simple linear space algorithm based on the new formula can find a longest common increasing subsequence of sizes $n$ and $m$ respectively, in time $O(nm)$ using additional $\min\{n,m\}+1$ space. 
Daxin Zhu, Lei Wang, Tinran Wang, and Xiaodong Wang
cs.DS