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- Release Notes for MiniSat 2.2.0
- ===============================
-
- Changes since version 2.0:
-
- * Started using a more standard release numbering.
-
- * Includes some now well-known heuristics: phase-saving and luby
- restarts. The old heuristics are still present and can be activated
- if needed.
-
- * Detection/Handling of out-of-memory and vector capacity
- overflow. This is fairly new and relatively untested.
-
- * Simple resource controls: CPU-time, memory, number of
- conflicts/decisions.
-
- * CPU-time limiting is implemented by a more general, but simple,
- asynchronous interruption feature. This means that the solving
- procedure can be interrupted from another thread or in a signal
- handler.
-
- * Improved portability with respect to building on Solaris and with
- Visual Studio. This is not regularly tested and chances are that
- this have been broken since, but should be fairly easy to fix if
- so.
-
- * Changed C++ file-extention to the less problematic ".cc".
-
- * Source code is now namespace-protected
-
- * Introducing a new Clause Memory Allocator that brings reduced
- memory consumption on 64-bit architechtures and improved
- performance (to some extent). The allocator uses a region-based
- approach were all references to clauses are represented as a 32-bit
- index into a global memory region that contains all clauses. To
- free up and compact memory it uses a simple copying garbage
- collector.
-
- * Improved unit-propagation by Blocking Literals. For each entry in
- the watcher lists, pair the pointer to a clause with some
- (arbitrary) literal from the clause. The idea is that if the
- literal is currently true (i.e. the clause is satisfied) the
- watchers of the clause does not need to be altered. This can thus
- be detected without touching the clause's memory at all. As often
- as can be done cheaply, the blocking literal for entries to the
- watcher list of a literal 'p' is set to the other literal watched
- in the corresponding clause.
-
- * Basic command-line/option handling system. Makes it easy to specify
- options in the class that they affect, and whenever that class is
- used in an executable, parsing of options and help messages are
- brought in automatically.
-
- * General clean-up and various minor bug-fixes.
-
- * Changed implementation of variable-elimination/model-extension:
-
- - The interface is changed so that arbitrary remembering is no longer
- possible. If you need to mention some variable again in the future,
- this variable has to be frozen.
-
- - When eliminating a variable, only clauses that contain the variable
- with one sign is necessary to store. Thereby making the other sign
- a "default" value when extending models.
-
- - The memory consumption for eliminated clauses is further improved
- by storing all eliminated clauses in a single contiguous vector.
-
- * Some common utility code (I/O, Parsing, CPU-time, etc) is ripped
- out and placed in a separate "utils" directory.
-
- * The DIMACS parse is refactored so that it can be reused in other
- applications (not very elegant, but at least possible).
-
- * Some simple improvements to scalability of preprocessing, using
- more lazy clause removal from data-structures and a couple of
- ad-hoc limits (the longest clause that can be produced in variable
- elimination, and the longest clause used in backward subsumption).
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