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feat: no additional variables during constraint construction #131

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merged 1 commit into from
Jan 22, 2025
Merged

feat: no additional variables during constraint construction #131

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9 changes: 4 additions & 5 deletions pumpkin-solver/src/bin/pumpkin-solver/flatzinc/compiler/post_constraints.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -451,12 +451,11 @@ fn compile_bool2int(
let a = context.resolve_bool_variable(&exprs[0])?;
let b = context.resolve_integer_variable(&exprs[1])?;

Ok(constraints::binary_equals(
a,
context.solver.new_literal_for_predicate(predicate!(b == 1)),
Ok(
constraints::binary_equals(a.get_integer_variable(), b.scaled(1))
.post(context.solver, None)
.is_ok(),
)
.post(context.solver, None)
.is_ok())
}

fn compile_bool_or(
Expand Down
49 changes: 10 additions & 39 deletions pumpkin-solver/src/constraints/boolean.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -3,7 +3,6 @@ use std::num::NonZero;
use super::equals;
use super::less_than_or_equals;
use super::Constraint;
use crate::predicate;
use crate::variables::AffineView;
use crate::variables::DomainId;
use crate::variables::Literal;
Expand Down Expand Up @@ -49,7 +48,7 @@ impl Constraint for BooleanLessThanOrEqual {
solver: &mut Solver,
tag: Option<NonZero<u32>>,
) -> Result<(), ConstraintOperationError> {
let domains = self.create_domains(solver);
let domains = self.create_domains();

less_than_or_equals(domains, self.rhs).post(solver, tag)
}
Expand All @@ -60,34 +59,19 @@ impl Constraint for BooleanLessThanOrEqual {
reification_literal: Literal,
tag: Option<NonZero<u32>>,
) -> Result<(), ConstraintOperationError> {
let domains = self.create_domains(solver);
let domains = self.create_domains();

less_than_or_equals(domains, self.rhs).implied_by(solver, reification_literal, tag)
}
}

impl BooleanLessThanOrEqual {
fn create_domains(&self, solver: &mut Solver) -> Vec<AffineView<DomainId>> {
let domains = self
.bools
fn create_domains(&self) -> Vec<AffineView<DomainId>> {
self.bools
.iter()
.enumerate()
.map(|(index, bool)| {
let corresponding_domain_id = solver.new_bounded_integer(0, 1);
// bool -> [domain = 1]
let _ = solver.add_clause([
!(*bool).get_true_predicate(),
predicate![corresponding_domain_id >= 1],
]);
// !bool -> [domain = 0]
let _ = solver.add_clause([
bool.get_true_predicate(),
predicate![corresponding_domain_id <= 0],
]);
corresponding_domain_id.scaled(self.weights[index])
})
.collect::<Vec<_>>();
domains
.map(|(index, bool)| bool.get_integer_variable().scaled(self.weights[index]))
.collect()
}
}

Expand All @@ -103,7 +87,7 @@ impl Constraint for BooleanEqual {
solver: &mut Solver,
tag: Option<NonZero<u32>>,
) -> Result<(), ConstraintOperationError> {
let domains = self.create_domains(solver);
let domains = self.create_domains();

equals(domains, 0).post(solver, tag)
}
Expand All @@ -114,31 +98,18 @@ impl Constraint for BooleanEqual {
reification_literal: Literal,
tag: Option<NonZero<u32>>,
) -> Result<(), ConstraintOperationError> {
let domains = self.create_domains(solver);
let domains = self.create_domains();

equals(domains, 0).implied_by(solver, reification_literal, tag)
}
}

impl BooleanEqual {
fn create_domains(&self, solver: &mut Solver) -> Vec<AffineView<DomainId>> {
fn create_domains(&self) -> Vec<AffineView<DomainId>> {
self.bools
.iter()
.enumerate()
.map(|(index, bool)| {
let corresponding_domain_id = solver.new_bounded_integer(0, 1);
// bool -> [domain = 1]
let _ = solver.add_clause([
!(*bool).get_true_predicate(),
predicate![corresponding_domain_id >= 1],
]);
// !bool -> [domain = 0]
let _ = solver.add_clause([
(*bool).get_true_predicate(),
predicate![corresponding_domain_id <= 0],
]);
corresponding_domain_id.scaled(self.weights[index])
})
.map(|(index, bool)| bool.get_integer_variable().scaled(self.weights[index]))
.chain(std::iter::once(self.rhs.scaled(-1)))
.collect()
}
Expand Down
4 changes: 4 additions & 0 deletions pumpkin-solver/src/engine/variables/literal.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,10 @@ impl Literal {
}
}

pub fn get_integer_variable(&self) -> AffineView<DomainId> {
self.integer_variable
}

pub fn get_true_predicate(&self) -> Predicate {
self.lower_bound_predicate(1)
}
Expand Down
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