Inconsistent behaviour of deletion

[bartbog]

Currently, deletion by find decreases the number of occurrences of a constraint by one. However, the check whether this reaches zero is only done in del find, not in del id.

Minimal example to see this fail:

CNF formula:

p cnf 1 1 
1 0

PROOF:

pseudo-Boolean proof version 1.0
f 1
red 1 x2 >= 1 ; x2 -> 1 ; 
* "1 x2 >= 1" is now ONE time in the database (id 2)
u 1 x2 >= 1;
* "1 x2 >= 1" is now TWO times in the database (id 2, 3)
* first deleting with find (one occ), then with id means it is not deleted: 
del find 1 x2 >= 1 ;
* "1 x2 >= 1" is now STILL TWO times in the database (despite delete) 
del id 2 
* "1 x2 >= 1" is now ONE times in the database (despite two deletes) 
u 1 x2 >= 1;
* "1 x2 >= 1" is now TWO times in the database (id3,4). This derivation USES the fact that the constraint 3 was still in the database
del find 1 x2 >= 1 ;
* A single delete has deleted the TWO occurrences.

[StephanGocht]

Thanks for the report. The issue should be fixed in f2abaa0, test case added in 64eb522 .