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Merge pull request #126 from ahorn/minimum

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Basic infrastructure for minimum aggregation function
This commit is contained in:
Nikolaj Bjorner 2015-06-11 09:38:39 -07:00
commit 94f8ecb06d
17 changed files with 550 additions and 10 deletions
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68
src/ast/dl_decl_plugin.cpp
View file

@ -44,7 +44,8 @@ namespace datalog {
m_num_sym("N"),
m_lt_sym("<"),
m_le_sym("<="),
m_rule_sym("R")
m_rule_sym("R"),
m_min_sym("min")
{
}
@ -490,6 +491,66 @@ namespace datalog {
return m_manager->mk_func_decl(m_clone_sym, 1, &s, s, info);
}
/**
In SMT2 syntax, we can write \c ((_ min R N) v_0 v_1 ... v_k)) where 0 <= N <= k,
R is a relation of sort V_0 x V_1 x ... x V_k and each v_i is a zero-arity function
(also known as a "constant" in SMT2 parlance) whose range is of sort V_i.
Example:
(define-sort number_t () (_ BitVec 2))
(declare-rel numbers (number_t number_t))
(declare-rel is_min (number_t number_t))
(declare-var x number_t)
(declare-var y number_t)
(rule (numbers #b00 #b11))
(rule (numbers #b00 #b01))
(rule (=> (and (numbers x y) ((_ min numbers 1) x y)) (is_min x y)))
This says that we want to find the mininum y grouped by x.
*/
func_decl * dl_decl_plugin::mk_min(decl_kind k, unsigned num_parameters, parameter const * parameters) {
if (num_parameters < 2) {
m_manager->raise_exception("invalid min aggregate definition due to missing parameters");
return 0;
}
parameter const & relation_parameter = parameters[0];
if (!relation_parameter.is_ast() || !is_func_decl(relation_parameter.get_ast())) {
m_manager->raise_exception("invalid min aggregate definition, first parameter is not a function declaration");
return 0;
}
func_decl* f = to_func_decl(relation_parameter.get_ast());
if (!m_manager->is_bool(f->get_range())) {
m_manager->raise_exception("invalid min aggregate definition, first paramater must be a predicate");
return 0;
}
parameter const & min_col_parameter = parameters[1];
if (!min_col_parameter.is_int()) {
m_manager->raise_exception("invalid min aggregate definition, second parameter must be an integer");
return 0;
}
if (min_col_parameter.get_int() < 0) {
m_manager->raise_exception("invalid min aggregate definition, second parameter must be non-negative");
return 0;
}
if ((unsigned)min_col_parameter.get_int() >= f->get_arity()) {
m_manager->raise_exception("invalid min aggregate definition, second parameter exceeds the arity of the relation");
return 0;
}
func_decl_info info(m_family_id, k, num_parameters, parameters);
SASSERT(f->get_info() == 0);
return m_manager->mk_func_decl(m_min_sym, f->get_arity(), f->get_domain(), f->get_range(), info);
}
func_decl * dl_decl_plugin::mk_func_decl(
decl_kind k, unsigned num_parameters, parameter const * parameters,
unsigned arity, sort * const * domain, sort * range) {
@ -617,6 +678,9 @@ namespace datalog {
break;
}
case OP_DL_MIN:
return mk_min(k, num_parameters, parameters);
default:
m_manager->raise_exception("operator not recognized");
return 0;
@ -627,7 +691,7 @@ namespace datalog {
}
void dl_decl_plugin::get_op_names(svector<builtin_name> & op_names, symbol const & logic) {
op_names.push_back(builtin_name(m_min_sym.bare_str(), OP_DL_MIN));
}
void dl_decl_plugin::get_sort_names(svector<builtin_name> & sort_names, symbol const & logic) {

59
src/ast/dl_decl_plugin.h
View file

@ -50,6 +50,7 @@ namespace datalog {
OP_DL_LT,
OP_DL_REP,
OP_DL_ABS,
OP_DL_MIN,
LAST_RA_OP
};
@ -71,6 +72,7 @@ namespace datalog {
symbol m_lt_sym;
symbol m_le_sym;
symbol m_rule_sym;
symbol m_min_sym;
bool check_bounds(char const* msg, unsigned low, unsigned up, unsigned val) const;
bool check_domain(unsigned low, unsigned up, unsigned val) const;
@ -94,12 +96,69 @@ namespace datalog {
func_decl * mk_compare(decl_kind k, symbol const& sym, sort*const* domain);
func_decl * mk_clone(sort* r);
func_decl * mk_rule(unsigned arity);
func_decl * mk_min(decl_kind k, unsigned num_parameters, parameter const * parameters);
sort * mk_finite_sort(unsigned num_params, parameter const* params);
sort * mk_relation_sort(unsigned num_params, parameter const* params);
sort * mk_rule_sort();
public:
/**
Is \c decl a min aggregation function?
*/
static bool is_aggregate(const func_decl* const decl)
{
return decl->get_decl_kind() == OP_DL_MIN;
}
/**
\pre: is_aggregate(aggregate)
\returns function declaration of predicate which is subject to min aggregation function
*/
static func_decl * min_func_decl(const func_decl* const aggregate)
{
SASSERT(is_aggregate(aggregate));
parameter const & relation_parameter = aggregate->get_parameter(0);
return to_func_decl(relation_parameter.get_ast());
}
/**
\pre: is_aggregate(aggregate)
\returns column identifier (starting at zero) which is minimized by aggregation function
*/
static unsigned min_col(const func_decl* const aggregate)
{
SASSERT(is_aggregate(aggregate));
return (unsigned)aggregate->get_parameter(1).get_int();
}
/**
\pre: is_aggregate(aggregate)
\returns column identifiers for the "group by" in the given min aggregation function
*/
static unsigned_vector group_by_cols(const func_decl* const aggregate)
{
SASSERT(is_aggregate(aggregate));
unsigned _min_col = min_col(aggregate);
if (aggregate->get_arity() == 0U)
return unsigned_vector();
unsigned col_num = 0;
unsigned_vector cols(aggregate->get_arity() - 1U);
for (unsigned i = 0; i < cols.size(); ++i, ++col_num)
{
if (col_num == _min_col)
++col_num;
cols[i] = col_num;
}
return cols;
}
dl_decl_plugin();
virtual ~dl_decl_plugin() {}