z3/src/muz/transforms/dl_mk_scale.cpp

/*++
Copyright (c) 2013 Microsoft Corporation

Module Name:

    dl_mk_scale.cpp

Abstract:


Author:

    Nikolaj Bjorner (nbjorner) 2013-08-19

Revision History:

--*/

#include "muz/transforms/dl_mk_scale.h"
#include "muz/base/dl_context.h"
#include "muz/base/fp_params.hpp"

namespace datalog {

    class mk_scale::scale_model_converter : public model_converter {
        ast_manager& m;
        func_decl_ref_vector m_trail;
        arith_util   a;
        obj_map<func_decl, func_decl*> m_new2old;
    public:
        scale_model_converter(ast_manager& m): m(m), m_trail(m), a(m) {}

        void add_new2old(func_decl* new_f, func_decl* old_f) {
            m_trail.push_back(old_f);
            m_trail.push_back(new_f);
            m_new2old.insert(new_f, old_f);
        }

        void get_units(obj_map<expr, bool>& units) override { units.reset(); }

        void operator()(model_ref& md) override {
            model_ref old_model = alloc(model, m);
            for (auto const& kv : m_new2old) {
                func_decl* old_p = kv.m_value;
                func_decl* new_p = kv.m_key;
				func_interp* new_fi = md->get_func_interp(new_p);
				expr_ref_vector subst(m);
				var_subst vs(m, false);
				expr_ref tmp(m);

				if (!new_fi) {
					TRACE(dl, tout << new_p->get_name() << " has no value in the current model\n";);
					continue;
				}
				for (unsigned i = 0; i < old_p->get_arity(); ++i) {
					subst.push_back(m.mk_var(i, old_p->get_domain(i)));
				}
				subst.push_back(a.mk_numeral(rational(1), a.mk_real()));

				SASSERT(!new_fi->is_partial() && new_fi->num_entries() == 0);
				tmp = vs(new_fi->get_else(), subst.size(), subst.data());
				if (old_p->get_arity() == 0) {
					old_model->register_decl(old_p, tmp);
				}
				else {
					func_interp* old_fi = alloc(func_interp, m, old_p->get_arity());
					// Hedge that we don't have to handle the general case for models produced
					// by Horn clause solvers.
					old_fi->set_else(tmp);
					old_model->register_decl(old_p, old_fi);
				}
            }

            // register values that have not been scaled.
            unsigned sz = md->get_num_constants();
            for (unsigned i = 0; i < sz; ++i) {
                func_decl* c = md->get_constant(i);
                if (!m_new2old.contains(c)) {
                    old_model->register_decl(c, md->get_const_interp(c));
                }
            }
            sz = md->get_num_functions();
            for (unsigned i = 0; i < sz; ++i) {
                func_decl* f = md->get_function(i);
                if (!m_new2old.contains(f)) {
                    func_interp* fi = md->get_func_interp(f);
                    old_model->register_decl(f, fi->copy());
                }
            }
            md = old_model;
            //TRACE(dl, model_smt2_pp(tout, m, *md, 0); );
        }

        model_converter * translate(ast_translation & translator) override {
            UNREACHABLE();
            return nullptr;
        }

        void display(std::ostream& out) override { out << "(scale-model-converter)\n"; }

    };


    mk_scale::mk_scale(context & ctx, unsigned priority):
        plugin(priority),
        m(ctx.get_manager()),
        m_ctx(ctx),
        a(m),
        m_trail(m),
        m_eqs(m) {
    }

    rule_set * mk_scale::operator()(rule_set const & source) {
        if (!m_ctx.scale()) {
            return nullptr;
        }
        rule_manager& rm = source.get_rule_manager();
        scoped_ptr<rule_set> result = alloc(rule_set, m_ctx);
        unsigned sz = source.get_num_rules();
        rule_ref new_rule(rm);
        app_ref_vector tail(m);
        app_ref head(m);
        bool_vector neg;
        ptr_vector<sort> vars;
        ref<scale_model_converter> smc;
        if (m_ctx.get_model_converter()) {
            smc = alloc(scale_model_converter, m);
        }
        m_mc = smc.get();

        for (unsigned i = 0; i < sz; ++i) {
            rule & r = *source.get_rule(i);
            unsigned utsz = r.get_uninterpreted_tail_size();
            unsigned tsz  = r.get_tail_size();
            tail.reset();
            vars.reset();
            m_cache.reset();
            m_trail.reset();
            m_eqs.reset();
            r.get_vars(m, vars);
            unsigned num_vars = vars.size();
            for (unsigned j = 0; j < utsz; ++j) {
                tail.push_back(mk_pred(num_vars, r.get_tail(j)));
            }
            for (unsigned j = utsz; j < tsz; ++j) {
                tail.push_back(mk_constraint(num_vars, r.get_tail(j)));
            }
            app_ref new_pred = mk_pred(num_vars, r.get_head());
            tail.append(m_eqs);
            tail.push_back(a.mk_gt(m.mk_var(num_vars, a.mk_real()), a.mk_numeral(rational(0), false)));
            neg.resize(tail.size(), false);
            new_rule = rm.mk(new_pred, tail.size(), tail.data(), neg.data(), r.name(), true);
            result->add_rule(new_rule);
            if (source.is_output_predicate(r.get_decl())) {
                result->set_output_predicate(new_rule->get_decl());
            }
        }
        TRACE(dl, result->display(tout););
        if (m_mc) {
            m_ctx.add_model_converter(m_mc);
        }
        m_trail.reset();
        m_cache.reset();
        return result.detach();
    }

    app_ref mk_scale::mk_pred(unsigned sigma_idx, app* q) {
        func_decl* f = q->get_decl();
        ptr_vector<sort> domain(f->get_arity(), f->get_domain());
        domain.push_back(a.mk_real());
        func_decl_ref g(m);
        g = m.mk_func_decl(f->get_name(), f->get_arity() + 1, domain.data(), f->get_range());
        expr_ref_vector args(m);
        for (unsigned i = 0; i < q->get_num_args(); ++i) {
            expr* arg = q->get_arg(i);
            rational val;
            if (a.is_numeral(arg, val)) {
                if (val.is_zero()) {
                    // arg is unchanged.
                }
                else if (val.is_one()) {
                    arg = m.mk_var(sigma_idx, a.mk_real());
                }
                else {
                    // create a fresh variable 'v', add 'v == sigma*arg'
                    expr* v = m.mk_var(sigma_idx + 1 + m_eqs.size(), a.mk_real());
                    m_eqs.push_back(m.mk_eq(v, a.mk_mul(arg, m.mk_var(sigma_idx, a.mk_real()))));
                    arg = v;
                }
            }
            args.push_back(arg);
        }
        args.push_back(m.mk_var(sigma_idx, a.mk_real()));
        m_ctx.register_predicate(g, false);
        if (m_mc) {
            m_mc->add_new2old(g, f);
        }
        return app_ref(m.mk_app(g, q->get_num_args() + 1, args.data()), m);
    }

    app_ref mk_scale::mk_constraint(unsigned sigma_idx, app* q) {
        expr* r = linearize(sigma_idx, q);
        SASSERT(is_app(r));
        return app_ref(to_app(r), m);
    }

    expr* mk_scale::linearize(unsigned sigma_idx, expr* e) {
        expr* r;
        if (m_cache.find(e, r)) {
            return r;
        }
        if (!is_app(e)) {
            return e;
        }
        expr_ref result(m);
        app* ap = to_app(e);
        if (ap->get_family_id() == m.get_basic_family_id() ||
            a.is_add(e) || a.is_sub(e) ||
            a.is_le(e)  || a.is_ge(e)  ||
            a.is_lt(e)  || a.is_gt(e)) {
            expr_ref_vector args(m);
            for (unsigned i = 0; i < ap->get_num_args(); ++i) {
                args.push_back(linearize(sigma_idx, ap->get_arg(i)));
            }
            result = m.mk_app(ap->get_decl(), args.size(), args.data());
        }
        else if (a.is_numeral(e)) {
            result = a.mk_mul(m.mk_var(sigma_idx, a.mk_real()), e);
        }
        else {
            result = e;
        }
        m_trail.push_back(result);
        m_cache.insert(e, result);
        return result;
    }

};