Hello, I have 2 strictly ordered sequences of dates t1... tn, and td1...tdm, where m and n may or may not be different. We always have: t1<...<tn and td1<...<tdm. I am trying to place the (t1...tn) sequence over the (td1...tdm) sequence, and generate all these "permutations" ie . all ti < td1 or. all ti < tn = td1 or. all ti except tn < td1 and (tn >td1 or tn=td2 or td3>tn>td2 or tn=td3 or ....tn>tdm-1 or tn=tdm or tn>tdm) or. t1...tn-2 < td1 and tn-1=td1 and (td1<tn<td2 or tn=td2 or tn>td2 or tn=td3 or ....tn>tdm-1 or tn=tdm or tn>tdm) or. t1...tn-2 < td1 and td1<tn-1<td2 and (the same) or. t1...tn-2 < td1 and td2=tn-1 and (the same) ...etc...etc or. t1 < td1 and distribute the rest of t_i_s or. t1 = td1 and distribute the rest of t_i_s or. td2> t1 > td1 and distribute the rest of t_i_s etc or. tdm< t1< t2< ...<tn I hope the description is clear enough even though it is not formal at all. The problem is like distributing n balls over m-1 buckets or to the left or to the right of all buckets or exactly at bucket borders (with never more than 1 t_i on any bucket order) In the runtime world, the pseudo-code would look like: calling i0: number of t_is in the 0th bucket (the one to the left) calling i1: number of t_is in the 1th bucket (between td1 and td2) ... calling im-1: number of t_is in the (m-1)th bucket (between tdm-1 and tdm) calling im: number of t_is in the mth bucket (>tdm) j1 : number of t_is = td1 (0 or 1) ... jm: number of t_is = tdm (0 or 1) for (i0 = n; i0>=0; --i0) for (i1 = n-i0; i1>=0; --i1) for (i2 = n-i0-i1; i2>=0; --i2) ... for (im = n-i0-i1-im_1; im>=0; --im) ... 0. The pseudo code is incorrect here. I need to account for the j_s as well. 1. I would normally think of using recursion to generate the serie of inner-loops. 2. I believe there must be a purely iterative solution. 3. This problem seems familiar in that perhaps one of the STL algorithm does something similar 4. n and m are never bigger than 4 or 5. Though already, that yields a large number of permutations. I haven't figured out yet the exact number. So I think compilation will be slow but not unbearably (it's a guess). I am interested in doing this in compile-time though. I encode dates as an ints. I would start with the td dates the mpl::vector_c< 20100109, 20100125, 20100322, 201004228 > which gives m=4. Then I would set n to 3 for e.g. Then I would ask the mpl metafunction to return all the possible combinations. That would be a vector or vectors? vector_c< permut1, permumt2, ... permut_last > For each vector of the permut_s, I would have a runtime function to run (chooses dates and distribute them as provided by the vector). Regards,