news for release ala since release al6
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simpdelay=100 option to delay preprocessing for faster incremental use

news for release al6 since release 587
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cloning in plingeling
better simplification scheduling
cleaned up code and removed irrelevant algorithms
lglrepr + lglfork + lgljoin + lglookahead
pure simplification mode

news for release 587 since first public release 276
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lifting units and equivalences
sharing of equivalences in parallel solver
reusing of trail after restart
unhiding hidden tautologies, hidden literal removal, variable elimination
dynamic activity versus glue based reductions
capping of long learned clauses
poison flag for minimization
partially flipping initial phase during rebias and rephrasing
more aggressive rebias
setting options through environment variables
initial incremental interface with one assumption
optional tracing of API calls
added missing reschedule when using '--bias' option
improved verbose messages for plingeling

news for release 276 since competition version 271
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added '-i' option to ignore additional clauses
better logging and verbose messages
first worker of plingling = lingeling
externalized parameters: lhbr, redlmininc
cleaned up unused code
