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Fix the cohesion of the model when a view is part of unification #90

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merged 1 commit into from
Aug 21, 2024
Merged

Fix the cohesion of the model when a view is part of unification #90

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19 changes: 19 additions & 0 deletions crates/fzn-huub/corpus/unify_with_view.fzn.json
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Original file line number Diff line number Diff line change
@@ -0,0 +1,19 @@
{
"variables": {
"x" : { "type" : "bool"},
"y" : { "type" : "bool"},
"z" : { "type" : "bool"},
"ivar" : { "type" : "int", "domain" : [[1, 3]]}
},
"arrays": {

},
"constraints": [
{ "id" : "bool_eq", "args" : ["x", "y"], "ann" : ["domain_change_constraint"]},
{ "id" : "bool_eq", "args" : ["x", "z"], "ann" : ["domain_change_constraint"]},
{ "id" : "int_le_reif", "args" : ["ivar", 2, "x"], "defines" : "x"}
],
"output": ["x", "y", "z", "ivar"],
"solve": { "method" : "satisfy"},
"version": "1.0"
}
16 changes: 16 additions & 0 deletions crates/fzn-huub/corpus/unify_with_view.sol
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Original file line number Diff line number Diff line change
@@ -0,0 +1,16 @@
x = false;
y = false;
z = false;
ivar = 3;
----------
x = true;
y = true;
z = true;
ivar = 1;
----------
x = true;
y = true;
z = true;
ivar = 2;
----------
==========
1 change: 1 addition & 0 deletions crates/fzn-huub/tests/flatzinc_tests.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,7 @@ mod tests {
assert_all_solutions!(unification);
assert_all_solutions!(unify_element_1);
assert_all_solutions!(unify_element_2);
assert_all_solutions!(unify_with_view);

assert_optimal!(jobshop);

Expand Down
285 changes: 163 additions & 122 deletions crates/huub/src/model/flatzinc.rs
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Original file line number Diff line number Diff line change
@@ -1,6 +1,6 @@
use std::{
cell::RefCell,
collections::BTreeMap,
collections::{btree_map::Entry, BTreeMap},
fmt::{Debug, Display},
ops::Deref,
rc::Rc,
Expand Down Expand Up @@ -35,8 +35,120 @@ impl Model {
let mut map = BTreeMap::<S, ModelView>::new();
let mut prb = Model::default();

// Unify variables (e.g., from `bool_eq` and `int_eq` constraints)
// Extract views from `defines_var` constraints
let mut processed = vec![false; fzn.constraints.len()];
for (i, c) in fzn.constraints.iter().enumerate() {
let mut add_view = |map: &mut BTreeMap<_, _>, name: S, view: ModelView| {
let e = map.insert(name, view);
debug_assert!(e.is_none());
processed[i] = true;
};

match (c.id.deref(), c.defines.as_ref()) {
("bool2int", Some(l)) => {
if let [b, Argument::Literal(Literal::Identifier(x))] = c.args.as_slice() {
if x == l {
let b = arg_bool(fzn, &mut prb, &mut map, b)?;
add_view(&mut map, l.clone(), IntView::from(b).into());
}
}
}
("bool_not", Some(l)) => match c.args.as_slice() {
[Argument::Literal(Literal::Identifier(x)), b]
| [b, Argument::Literal(Literal::Identifier(x))]
if x == l =>
{
let b = arg_bool(fzn, &mut prb, &mut map, b)?;
add_view(&mut map, l.clone(), (!b).into());
}
_ => {}
},
("int_eq_reif", Some(l)) => match c.args.as_slice() {
[Argument::Literal(Literal::Int(i)), Argument::Literal(x), Argument::Literal(Literal::Identifier(r))]
| [Argument::Literal(x), Argument::Literal(Literal::Int(i)), Argument::Literal(Literal::Identifier(r))]
if r == l =>
{
let x = lit_int(fzn, &mut prb, &mut map, x)?;
add_view(&mut map, l.clone(), BoolView::IntEq(Box::new(x), *i).into());
}
_ => {}
},
("int_le_reif", Some(l)) => match c.args.as_slice() {
[Argument::Literal(Literal::Int(i)), Argument::Literal(x), Argument::Literal(Literal::Identifier(r))]
if r == l =>
{
let x = lit_int(fzn, &mut prb, &mut map, x)?;
add_view(
&mut map,
l.clone(),
BoolView::IntGreaterEq(Box::new(x), *i).into(),
);
}
[Argument::Literal(x), Argument::Literal(Literal::Int(i)), Argument::Literal(Literal::Identifier(r))]
if r == l =>
{
let x = lit_int(fzn, &mut prb, &mut map, x)?;
add_view(
&mut map,
l.clone(),
BoolView::IntLessEq(Box::new(x), *i).into(),
);
}
_ => {}
},
("int_ne_reif", Some(l)) => match c.args.as_slice() {
[Argument::Literal(Literal::Int(i)), Argument::Literal(x), Argument::Literal(Literal::Identifier(r))]
| [Argument::Literal(x), Argument::Literal(Literal::Int(i)), Argument::Literal(Literal::Identifier(r))]
if r == l =>
{
let x = lit_int(fzn, &mut prb, &mut map, x)?;
add_view(
&mut map,
l.clone(),
BoolView::IntNotEq(Box::new(x), *i).into(),
);
}
_ => {}
},
("int_lin_eq", Some(l))
if c.args
.get(1)
.map(|v| arg_has_length(fzn, v, 2))
.unwrap_or(false) =>
'int_lin_eq: {
let [coeff, vars, sum] = c.args.as_slice() else {
break 'int_lin_eq;
};
let coeff = arg_array(fzn, coeff)?;
let vars = arg_array(fzn, vars)?;
let (c, (cy, vy)) = match vars.as_slice() {
[Literal::Identifier(v), y] if v == l => {
(par_int(fzn, &coeff[0])?, (par_int(fzn, &coeff[1])?, y))
}
[y, Literal::Identifier(v)] if v == l => {
(par_int(fzn, &coeff[1])?, (par_int(fzn, &coeff[0])?, y))
}
_ => break 'int_lin_eq,
};
let sum = arg_par_int(fzn, sum)?;
// c * l + cy * y = sum === l = (sum - cy * y) / c
if cy % c != 0 || sum % c != 0 {
break 'int_lin_eq;
}
let offset = sum / c;
let view = if let Some(scale) = NonZeroIntVal::new(-cy / c) {
let y = lit_int(fzn, &mut prb, &mut map, vy)?;
y * scale + offset
} else {
IntView::Const(offset)
};
add_view(&mut map, l.clone(), view.into());
}
_ => {}
}
}

// Unify variables (e.g., from `bool_eq` and `int_eq` constraints)
let mut unify_map = BTreeMap::<S, Rc<RefCell<Vec<Literal<S>>>>>::new();
let unify_map_find = |map: &BTreeMap<S, Rc<RefCell<Vec<Literal<S>>>>>, a: &Literal<S>| {
if let Literal::Identifier(x) = a {
Expand Down Expand Up @@ -124,7 +236,8 @@ impl Model {
}
let ty = &fzn.variables[&k].ty;
let li = li.borrow();
let var = match ty {
// Determine the domain of the list of literals
let domain: Option<Literal<S>> = match ty {
Type::Bool => {
let mut domain = None;
for lit in li.iter() {
Expand All @@ -140,10 +253,7 @@ impl Model {
_ => unreachable!(),
};
}
match domain {
Some(b) => ModelView::Bool(BoolView::Const(b)),
None => ModelView::Bool(prb.new_bool_var()),
}
domain.map(Literal::Bool)
}
Type::Int => {
let mut domain = None::<RangeList<IntVal>>;
Expand All @@ -169,129 +279,60 @@ impl Model {
_ => unreachable!(),
};
}
if let Some(domain) = domain {
if domain.is_empty() {
return Err(ReformulationError::TrivialUnsatisfiable.into());
} else if domain.card() == 1 {
ModelView::Int(IntView::Const(*domain.lower_bound().unwrap()))
} else {
ModelView::Int(prb.new_int_var(domain))
}
} else {
todo!("Variables without a domain are not yet supported")
}
domain.map(Literal::IntSet)
}
_ => unreachable!(),
};
// Find any view that is part of a unified group
let var = li
.iter()
.find_map(|lit| -> Option<ModelView> {
if let Literal::Identifier(id) = lit {
map.get(id).cloned()
} else {
None
}
})
// Create a new variable if no view is found
.unwrap_or_else(|| match domain {
Some(Literal::Bool(b)) => BoolView::Const(b).into(),
Some(Literal::IntSet(dom)) => prb.new_int_var(dom).into(),
Some(_) => unreachable!(),
None => match ty {
Type::Bool => prb.new_bool_var().into(),
Type::Int => panic!("unbounded integer variables are not supported yet"),
_ => unreachable!(),
},
});

// Map (or equate) all names in the group to the new variable
for lit in li.iter() {
if let Literal::Identifier(id) = lit {
let x = map.insert(id.clone(), var.clone());
debug_assert!(x.is_none());
}
}
}

// Extract views from `defines_var` constraints
for (i, c) in fzn.constraints.iter().enumerate() {
let mut mark_processed = || processed[i] = true;

match (c.id.deref(), c.defines.as_ref()) {
("bool2int", Some(l)) => {
if let [b, Argument::Literal(Literal::Identifier(x))] = c.args.as_slice() {
if x == l {
let b = arg_bool(fzn, &mut prb, &mut map, b)?;
let _ = map.insert(l.clone(), IntView::from(b).into());
mark_processed();
}
}
}
("bool_not", Some(l)) => match c.args.as_slice() {
[Argument::Literal(Literal::Identifier(x)), b]
| [b, Argument::Literal(Literal::Identifier(x))]
if x == l =>
{
let b = arg_bool(fzn, &mut prb, &mut map, b)?;
let _ = map.insert(l.clone(), (!b).into());
mark_processed();
}
_ => {}
},
("int_eq_reif", Some(l)) => match c.args.as_slice() {
[Argument::Literal(Literal::Int(i)), Argument::Literal(x), Argument::Literal(Literal::Identifier(r))]
| [Argument::Literal(x), Argument::Literal(Literal::Int(i)), Argument::Literal(Literal::Identifier(r))]
if r == l =>
{
let x = lit_int(fzn, &mut prb, &mut map, x)?;
let _ = map.insert(l.clone(), BoolView::IntEq(Box::new(x), *i).into());
mark_processed();
}
_ => {}
},
("int_le_reif", Some(l)) => match c.args.as_slice() {
[Argument::Literal(Literal::Int(i)), Argument::Literal(x), Argument::Literal(Literal::Identifier(r))]
if r == l =>
{
let x = lit_int(fzn, &mut prb, &mut map, x)?;
let _ =
map.insert(l.clone(), BoolView::IntGreaterEq(Box::new(x), *i).into());
mark_processed();
}
[Argument::Literal(x), Argument::Literal(Literal::Int(i)), Argument::Literal(Literal::Identifier(r))]
if r == l =>
{
let x = lit_int(fzn, &mut prb, &mut map, x)?;
let _ = map.insert(l.clone(), BoolView::IntLessEq(Box::new(x), *i).into());
mark_processed();
}
_ => {}
},
("int_ne_reif", Some(l)) => match c.args.as_slice() {
[Argument::Literal(Literal::Int(i)), Argument::Literal(x), Argument::Literal(Literal::Identifier(r))]
| [Argument::Literal(x), Argument::Literal(Literal::Int(i)), Argument::Literal(Literal::Identifier(r))]
if r == l =>
{
let x = lit_int(fzn, &mut prb, &mut map, x)?;
let _ = map.insert(l.clone(), BoolView::IntNotEq(Box::new(x), *i).into());
mark_processed();
}
_ => {}
},
("int_lin_eq", Some(l))
if c.args
.get(1)
.map(|v| arg_has_length(fzn, v, 2))
.unwrap_or(false) =>
'int_lin_eq: {
let [coeff, vars, sum] = c.args.as_slice() else {
break 'int_lin_eq;
};
let coeff = arg_array(fzn, coeff)?;
let vars = arg_array(fzn, vars)?;
let (c, (cy, vy)) = match vars.as_slice() {
[Literal::Identifier(v), y] if v == l => {
(par_int(fzn, &coeff[0])?, (par_int(fzn, &coeff[1])?, y))
}
[y, Literal::Identifier(v)] if v == l => {
(par_int(fzn, &coeff[1])?, (par_int(fzn, &coeff[0])?, y))
match map.entry(id.clone()) {
Entry::Vacant(e) => {
let _ = e.insert(var.clone());
}
_ => break 'int_lin_eq,
};
let sum = arg_par_int(fzn, sum)?;
// c * l + cy * y = sum === l = (sum - cy * y) / c
if cy % c != 0 || sum % c != 0 {
break 'int_lin_eq;
Entry::Occupied(e) => match ty {
Type::Bool => {
let (ModelView::Bool(new), ModelView::Bool(existing)) =
(var.clone(), e.get().clone())
else {
unreachable!()
};
prb += BoolExpr::Equiv(vec![new.into(), existing.into()])
}
Type::Int => {
let (ModelView::Int(new), ModelView::Int(existing)) =
(var.clone(), e.get().clone())
else {
unreachable!()
};
prb += Constraint::IntLinEq(vec![new, existing * -1], 0)
}
_ => unreachable!(),
},
}
let offset = sum / c;
let view = if let Some(scale) = NonZeroIntVal::new(-cy / c) {
let y = lit_int(fzn, &mut prb, &mut map, vy)?;
y * scale + offset
} else {
IntView::Const(offset)
};
let _ = map.insert(l.clone(), view.into());
mark_processed();
}
_ => {}
}
}

Expand Down
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