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    <p>You can do that by adding a new constraint that blocks the model returned by Z3. For example, suppose that in the model returned by Z3 we have that <code>x = 0</code> and <code>y = 1</code>. Then, we can block this model by adding the constraint <code>Or(x != 0, y != 1)</code>. The following script does the trick. You can try it online at: <a href="http://rise4fun.com/Z3Py/4blB" rel="noreferrer">http://rise4fun.com/Z3Py/4blB</a> </p> <p>Note that the following script has a couple of limitations. The input formula cannot include uninterpreted functions, arrays or uninterpreted sorts. </p> <pre><code>from z3 import * # Return the first "M" models of formula list of formulas F def get_models(F, M): result = [] s = Solver() s.add(F) while len(result) &lt; M and s.check() == sat: m = s.model() result.append(m) # Create a new constraint the blocks the current model block = [] for d in m: # d is a declaration if d.arity() &gt; 0: raise Z3Exception("uninterpreted functions are not supported") # create a constant from declaration c = d() if is_array(c) or c.sort().kind() == Z3_UNINTERPRETED_SORT: raise Z3Exception("arrays and uninterpreted sorts are not supported") block.append(c != m[d]) s.add(Or(block)) return result # Return True if F has exactly one model. def exactly_one_model(F): return len(get_models(F, 2)) == 1 x, y = Ints('x y') s = Solver() F = [x &gt;= 0, x &lt;= 1, y &gt;= 0, y &lt;= 2, y == 2*x] print get_models(F, 10) print exactly_one_model(F) print exactly_one_model([x &gt;= 0, x &lt;= 1, y &gt;= 0, y &lt;= 2, 2*y == x]) # Demonstrate unsupported features try: a = Array('a', IntSort(), IntSort()) b = Array('b', IntSort(), IntSort()) print get_models(a==b, 10) except Z3Exception as ex: print "Error: ", ex try: f = Function('f', IntSort(), IntSort()) print get_models(f(x) == x, 10) except Z3Exception as ex: print "Error: ", ex </code></pre>
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    1. USAdam Van Prooyen
    1. USLeonardo de Moura
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    1. COI also would like to ask, is the same possible in Z3's SMT language extension?
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      1. USDennis Yurichev
    2. CONo, it is not. However, I think it is a good idea to add this command in the SMT 2.0 front-end.
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      1. USLeonardo de Moura
    3. COCould you add a note to explain why uninterpreted functions and arrays are not supported using this method? Is it an accidental limitation (the data structures aren't ExprRefs, or something) or a more fundamental one?
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