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|
Quickstart Guide
================
First, create a cvc5 solver instance:
.. literalinclude:: ../../../../examples/api/python/quickstart.py
:language: python
:lines: 22
We will ask the solver to produce models and unsat cores in the following,
and for this we have to enable the following options.
.. literalinclude:: ../../../../examples/api/python/quickstart.py
:language: python
:lines: 26-27
Next we set the logic.
The simplest way to set a logic for the solver is to choose ``"ALL"``.
This enables all logics in the solver.
Alternatively, ``"QF_ALL"`` enables all logics without quantifiers.
To optimize the solver's behavior for a more specific logic,
use the logic name, e.g. ``"QF_BV"`` or ``"QF_AUFBV"``.
.. literalinclude:: ../../../../examples/api/python/quickstart.py
:language: python
:lines: 36
In the following, we will define constraints of reals and integers.
For this, we first query the solver for the corresponding sorts.
.. literalinclude:: ../../../../examples/api/python/quickstart.py
:language: python
:lines: 40-41
Now, we create two constants ``x`` and ``y`` of sort ``Real``,
and two constants ``a`` and ``b`` of sort ``Integer``.
Notice that these are *symbolic* constants, but not actual values.
.. literalinclude:: ../../../../examples/api/python/quickstart.py
:language: python
:lines: 46-49
We define the following constraints regarding ``x`` and ``y``:
.. math::
(0 < x) \wedge (0 < y) \wedge (x + y < 1) \wedge (x \leq y)
We construct the required terms and assert them as follows:
.. literalinclude:: ../../../../examples/api/python/quickstart.py
:language: python
:lines: 59-81
Now we check if the asserted formula is satisfiable, that is, we check if
there exist values of sort ``Real`` for ``x`` and ``y`` that satisfy all
the constraints.
.. literalinclude:: ../../../../examples/api/python/quickstart.py
:language: python
:lines: 85
The result we get from this satisfiability check is either ``sat``, ``unsat``
or ``unknown``.
It's status can be queried via `isSat`, `isUnsat` and `isSatUnknown` functions.
Alternatively, it can also be printed.
.. literalinclude:: ../../../../examples/api/python/quickstart.py
:language: python
:lines: 89-90
This will print:
.. code:: text
expected: sat
result: sat
Now, we query the solver for the values for ``x`` and ``y`` that satisfy
the constraints.
.. literalinclude:: ../../../../examples/api/python/quickstart.py
:language: python
:lines: 93-94
It is also possible to get values for terms that do not appear in the original
formula.
.. literalinclude:: ../../../../examples/api/python/quickstart.py
:language: python
:lines: 98-99
We can retrieve the Python representation of these values as follows.
.. literalinclude:: ../../../../examples/api/python/quickstart.py
:language: python
:lines: 102-108
This will print the following:
.. code:: text
value for x: 1/6
value for y: 1/6
value for x - y: 0
Another way to independently compute the value of ``x - y`` would be to
use the Python minus operator instead of asking the solver.
However, for more complex terms, it is easier to let the solver do the
evaluation.
.. literalinclude:: ../../../../examples/api/python/quickstart.py
:language: python
:lines: 114-118
This will print:
.. code:: text
computed correctly
Next, we will check satisfiability of the same formula,
only this time over integer variables ``a`` and ``b``.
For this, we first reset the assertions added to the solver.
.. literalinclude:: ../../../../examples/api/python/quickstart.py
:language: python
:lines: 130
Next, we assert the same assertions as above, but with integers.
This time, we inline the construction of terms
to the assertion command.
.. literalinclude:: ../../../../examples/api/python/quickstart.py
:language: python
:lines: 135-139
Now, we check whether the revised assertion is satisfiable.
.. literalinclude:: ../../../../examples/api/python/quickstart.py
:language: python
:lines: 142, 145-146
This time the asserted formula is unsatisfiable:
.. code:: text
expected: unsat
result: unsat
We can query the solver for an unsatisfiable core, that is, a subset
of the assertions that is already unsatisfiable.
.. literalinclude:: ../../../../examples/api/python/quickstart.py
:language: python
:lines: 150-152
This will print:
.. code:: text
unsat core size: 3
unsat core: [(< 0 a), (< 0 b), (< (+ a b) 1)]
Example
-------
| The SMT-LIB input for this example can be found at `examples/api/smtlib/quickstart.smt2 <https://github.com/cvc5/cvc5/blob/master/examples/api/smtlib/quickstart.smt2>`_.
| The source code for this example can be found at `examples/api/python/quickstart.py <https://github.com/cvc5/cvc5/blob/master/examples/api/python/quickstart.cpp>`_.
.. api-examples::
<examples>/api/cpp/quickstart.cpp
<examples>/api/java/QuickStart.java
<examples>/api/python/quickstart.py
<examples>/api/smtlib/quickstart.smt2
|
