Explore design space of endgame database building

[rhalbersma]

• Binomial coefficients
  • ranking/unranking of combinations (colex)
  • ranking/unranking of positions
  • increment/decrement of combinations (colex)
  • increment/decrement of positions
  • gappless position indexing
  • symmetry reduced indexing
• Subdivisions
  • by piece counts
  • by piece counts, leading ranks (any region)
  • by piece counts, leading ranks, leading rank configurations
  • by piece counts, leading ranks, leading rank configurations, subleading ranks
• Conversions
  • enumerate capture conversions
  • enumerate promotion conversions
  • enumerate leading rank conversions
  • enumerate subleading rank conversions
• Build dependencies
  • create Boost.Graph (vertices = subdivisions, edges = conversions)
  • topological sort for valid build order
  • total work
  • minimal memory requirements
  • uniform-cost search for critical path
  • potential parallelism
  • bread-first search for parallel build order
• Build algorithm
  • forward iteration
  • backward iteration
  • outcounting
  • leapfrog
  • one-sided vs. two-sided
• Metric
  • bitbases (won, not won)
  • WLD (win, loss, draw)
  • DTZ (distance to zeroing move)
  • DTM (distance to mate)
• Statistics
  • disk I/O
  • memory access
  • moves generated
  • moves done/undone
  • ranking/unranking
  • estimate performance model (per build algorithm)
  • automate build algorithm selection per subdivision
• Storage
  • design format of db, idx, log, stats files
  • serialization of std::vector, boost::dynamic_bitset
  • explore iostreams performance settings
• Compression
  • run-length
  • Tunstall
  • explore Re-Pair
• Access
  • LRU cache
  • explore memory mapped I/O