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add notes and unit tests

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2021-09-22 05:04:07 -07:00
parent 6478e789e9
commit dc55fbf30d
2 changed files with 138 additions and 13 deletions
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23
src/math/polysat/ule_constraint.cpp
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@ -12,7 +12,8 @@ Author:
Notes:
Rewrite rules to simplify expressions
Rewrite rules to simplify expressions.
In the following let k, k1, k2 be values.
- k1 <= k2 ==> 0 <= 0 if k1 <= k2
- k1 <= k2 ==> 1 <= 0 if k1 > k2
@ -21,9 +22,16 @@ Notes:
- k*2^n*p <= 0 ==> 2^n*p <= 0 if k is odd, leading coeffient is always a power of 2.
- k <= p ==> p - k <= - k - 1
TODO:
- p <= p + q ==> p <= -q - 1
- p + k <= p ==> p + k <= k - 1 for k > 0
TODO: clause simplifications:
- p + k <= p ==> p + k <= k or p = 0 for k != 0
- p*q = 0 ==> p = 0 or q = 0 applies to any factoring
- 2*p <= 2*q ==> (p >= 2^n-1 & q < 2^n-1) or (p >= 2^n-1 = q >= 2^n-1 & p <= q)
==> (p >= 2^n-1 => q < 2^n-1 or p <= q) &
(p < 2^n-1 => p <= q) &
(p < 2^n-1 => q < 2^n-1)
--*/
@ -53,7 +61,11 @@ namespace polysat {
if (m_rhs.is_val() && m_rhs.val() == m_rhs.manager().max_value()) {
m_lhs = 0, m_rhs = 0;
return;
}
}
if (m_lhs == m_rhs) {
m_lhs = m_rhs = 0;
return;
}
if (m_lhs.is_val() && m_rhs.is_val()) {
if (m_lhs.val() <= m_rhs.val())
m_lhs = m_rhs = 0;
@ -75,6 +87,7 @@ namespace polysat {
if (x.is_neg())
x = mod(x, m_lhs.manager().two_to_N());
m_lhs *= x;
SASSERT(m_lhs.leading_coefficient().is_power_of_two());
}
}