port more from hybridSMT

Signed-off-by: Lev Nachmanson <levnach@hotmail.com>

src/nlsat/CMakeLists.txt

@@ -7,7 +7,10 @@ z3_add_component(nlsat
     nlsat_simplify.cpp
     nlsat_solver.cpp
     nlsat_types.cpp
-  COMPONENT_DEPENDENCIES
+    nlsat_simple_checker.cpp
+    nlsat_variable_ordering_strategy.cpp
+    nlsat_symmetry_checker.cpp
+    COMPONENT_DEPENDENCIES
     polynomial
     sat
   PYG_FILES

src/nlsat/nlsat_params.pyg

@@ -3,7 +3,10 @@ def_module_params('nlsat',
                   description='nonlinear solver',
                   export=True,
                   params=(max_memory_param(),
+                          ('linxi_simple_check', BOOL, False, "linxi precheck about variables sign"),
+                          ('linxi_variable_ordering_strategy', UINT, 0, "linxi Variable Ordering Strategy, 0 for none, 1 for BROWN, 2 for TRIANGULAR, 3 for ONLYPOLY"),
                           ('cell_sample', BOOL, True, "cell sample projection"),
+                          ('linxi_symmetry_check', BOOL, False, "linxi symmetry check and learning"),
                           ('lazy', UINT, 0, "how lazy the solver is."),
                           ('reorder', BOOL, True, "reorder variables."),
                           ('log_lemmas', BOOL, False, "display lemmas as self-contained SMT formulas"),

src/nlsat/nlsat_simple_checker.h

@@ -0,0 +1,15 @@
+#include "math/polynomial/algebraic_numbers.h"
+#include "nlsat/nlsat_clause.h"
+
+
+namespace nlsat {
+    class Simple_Checker {
+        struct imp;
+        imp *  m_imp;
+    public:
+        // Simple_Checker(solver &_sol, pmanager &_pm, anum_manager &_am, const clause_vector &_clauses, clause_vector &_learned, const atom_vector &_atoms, const unsigned &_arith_var_num);
+        Simple_Checker(pmanager &_pm, anum_manager &_am, const clause_vector &_clauses, literal_vector &_learned_unit, const atom_vector &_atoms, const unsigned &_arith_var_num);
+        ~Simple_Checker();
+        bool operator()();
+    };
+}

src/nlsat/nlsat_symmetry_checker.cpp

@@ -0,0 +1,356 @@
+#include "nlsat/nlsat_symmetry_checker.h"
+
+struct Debug_Tracer {
+    std::string tag_str;
+    Debug_Tracer(std::string _tag_str) {
+        tag_str = _tag_str;
+        TRACE("linxi_symmetry_checker", 
+            tout << "Debug_Tracer begin\n";
+            tout << tag_str << "\n";
+        );
+    }
+    ~Debug_Tracer() {
+        TRACE("linxi_symmetry_checker", 
+            tout << "Debug_Tracer end\n";
+            tout << tag_str << "\n";
+        );
+    }
+};
+
+// #define _LINXI_DEBUG
+
+#ifdef _LINXI_DEBUG
+#define LINXI_DEBUG_CORE(x) std::stringstream DEBUG_ss_##x; DEBUG_ss_##x << __FUNCTION__ << " " << __FILE__ << ":" << __LINE__; Debug_Tracer DEBUG_dt_##x(DEBUG_ss_##x.str());
+#define LINXI_DEBUG_TRANS(x) LINXI_DEBUG_CORE(x);
+#define LINXI_DEBUG LINXI_DEBUG_TRANS(__LINE__);
+#define LINXI_HERE TRACE("linxi_symmetry_checker", tout << "here\n";);
+#else
+#define LINXI_DEBUG { }((void) 0 );
+#define LINXI_HERE { }((void) 0 );
+#endif
+
+
+
+namespace nlsat {
+    struct Symmetry_Checker::imp {
+        // solver              &sol;
+        pmanager            &pm;
+        unsynch_mpq_manager &qm;
+        const clause_vector &clauses;
+        const atom_vector   &atoms;
+        const bool_vector         &is_int;
+        const unsigned      arith_var_num;
+        // vector<unsigned long long> vars_hash;
+        vector<vector<unsigned>> vars_occur;
+        bool is_check;
+        var tx, ty;
+        struct Variable_Information {
+            unsigned long long hash_value;
+            unsigned deg;
+            var x;
+            bool is_int;
+            bool operator< (const Variable_Information &rhs) const {
+                return hash_value < rhs.hash_value;
+            }
+            bool operator== (const Variable_Information &rhs) const {
+                if (hash_value != rhs.hash_value)
+                    return false;
+                if (deg != rhs.deg)
+                    return false;
+                if (x != rhs.x)
+                    return false;
+                if (is_int != rhs.is_int)
+                    return false;
+                return true;
+            }
+            bool operator!= (const Variable_Information &rhs) const {
+                return !(*this == rhs);
+            }
+        };
+        unsigned long long VAR_BASE = 601;
+        void collect_var_info(Variable_Information &var_info, var x, unsigned deg) {
+            LINXI_DEBUG;
+            if (is_check) {
+                if (x == tx) {
+                    x = ty;
+                }
+                else if (x == ty) {
+                    x = tx;
+                }
+                else {
+                    // do nothing
+                }
+            }
+            else {
+                vars_occur[x].push_back(deg);
+            }
+            var_info.deg = deg;
+            var_info.x = x;
+            var_info.is_int = is_int[x];
+            var_info.hash_value = 0;
+            for (unsigned i = 0; i < deg; ++i) {
+                var_info.hash_value = var_info.hash_value*VAR_BASE + (unsigned long long)x;
+            }
+            var_info.hash_value = var_info.hash_value*VAR_BASE + (unsigned long long)var_info.is_int;
+        }
+        struct Monomial_Information {
+            unsigned long long hash_value;
+            unsigned long long coef;
+            vector<Variable_Information> vars_info;
+            bool operator< (const Monomial_Information &rhs) const {
+                return hash_value < rhs.hash_value;
+            }
+            bool operator== (const Monomial_Information &rhs) const {
+                if (hash_value != rhs.hash_value)
+                    return false;
+                if (coef != rhs.coef)
+                    return false;
+                if (vars_info.size() != rhs.vars_info.size())
+                    return false;
+                for (unsigned i = 0, sz = vars_info.size(); i < sz; ++i) {
+                    if (vars_info[i] != rhs.vars_info[i])
+                        return false;
+                }
+                return true;
+            }
+            bool operator!= (const Monomial_Information &rhs) const {
+                return !(*this == rhs);
+            }
+        };
+        unsigned long long MONO_BASE = 99991;
+
+        void collect_mono_info(Monomial_Information &mono_info, monomial *m, unsigned long long coef) {
+            LINXI_DEBUG;
+            unsigned sz = pm.size(m);
+            mono_info.vars_info.resize(sz);
+            for (unsigned i = 0; i < sz; ++i) {
+                collect_var_info(mono_info.vars_info[i], pm.get_var(m, i), pm.degree(m, i));
+            }
+            mono_info.coef = coef;
+            mono_info.hash_value = coef;
+            std::sort(mono_info.vars_info.begin(), mono_info.vars_info.end());
+            for (unsigned i = 0; i < sz; ++i) {
+                mono_info.hash_value = mono_info.hash_value*MONO_BASE + mono_info.vars_info[i].hash_value;
+            }
+        }
+        struct Polynomial_Information {
+            unsigned long long hash_value;
+            bool is_even;
+            vector<Monomial_Information> monos_info;
+            bool operator< (const Polynomial_Information &rhs) const {
+                return hash_value < rhs.hash_value;
+            }
+            bool operator== (const Polynomial_Information &rhs) const {
+                if (hash_value != rhs.hash_value)
+                    return false;
+                if (is_even != rhs.is_even)
+                    return false;
+                if (monos_info.size() != rhs.monos_info.size())
+                    return false;
+                for (unsigned i = 0, sz = monos_info.size(); i < sz; ++i) {
+                    if (monos_info[i] != rhs.monos_info[i])
+                        return false;
+                }
+                return true;
+            }
+            bool operator!= (const Polynomial_Information &rhs) const {
+                return !(*this == rhs);
+            }
+        };
+        unsigned long long POLY_BASE = 99991;
+        void collect_poly_info(Polynomial_Information &poly_info, poly *p, bool is_even) {
+            LINXI_DEBUG;
+            unsigned sz = pm.size(p);
+            poly_info.monos_info.resize(sz);
+            for (unsigned i = 0; i < sz; ++i) {
+                collect_mono_info(poly_info.monos_info[i], pm.get_monomial(p, i), qm.get_uint64(pm.coeff(p, i)));
+            }
+            poly_info.hash_value = 0;
+            std::sort(poly_info.monos_info.begin(), poly_info.monos_info.end());
+            for (unsigned i = 0; i < sz; ++i) {
+                poly_info.hash_value = poly_info.hash_value*POLY_BASE + poly_info.monos_info[i].hash_value;
+            }
+            poly_info.is_even = is_even;
+            if (is_even) {
+                poly_info.hash_value = poly_info.hash_value*poly_info.hash_value;
+            }
+        }
+        struct Atom_Information {
+            unsigned long long hash_value;
+            atom::kind akd;
+            vector<Polynomial_Information> polys_info;
+            bool operator< (const Atom_Information &rhs) const {
+                return hash_value < rhs.hash_value;
+            }
+            bool operator== (const Atom_Information &rhs) const {
+                if (hash_value != rhs.hash_value)
+                    return false;
+                if (akd != rhs.akd)
+                    return false;
+                if (polys_info.size() != rhs.polys_info.size())
+                    return false;
+                for (unsigned i = 0, sz = polys_info.size(); i < sz; ++i) {
+                    if (polys_info[i] != rhs.polys_info[i])
+                        return false;
+                }
+                return true;
+            }
+            bool operator!= (const Atom_Information &rhs) const {
+                return !(*this == rhs);
+            }
+        };
+        unsigned long long ATOM_BASE = 233;
+        void collect_atom_info(Atom_Information &atom_info, ineq_atom *iat) {
+            LINXI_DEBUG;
+            unsigned sz = iat->size();
+            atom_info.polys_info.resize(sz);
+            for (unsigned i = 0; i < sz; ++i) {
+                collect_poly_info(atom_info.polys_info[i], iat->p(i), iat->is_even(i));
+            }
+            atom_info.hash_value = 0;
+            std::sort(atom_info.polys_info.begin(), atom_info.polys_info.end());
+            for (unsigned i = 0; i < sz; ++i) {
+                atom_info.hash_value = atom_info.hash_value*ATOM_BASE + atom_info.polys_info[i].hash_value;
+            }
+            atom_info.akd = iat->get_kind();
+            atom_info.hash_value = atom_info.hash_value*ATOM_BASE + (unsigned long long)atom_info.akd;
+        }
+        struct Literal_Information {
+            unsigned long long hash_value;
+            vector<Atom_Information> atom_info; // not atoms
+            bool operator< (const Literal_Information &rhs) const {
+                return hash_value < rhs.hash_value;
+            }
+            bool operator== (const Literal_Information &rhs) const {
+                if (hash_value != rhs.hash_value)
+                    return false;
+                if (atom_info.size() != rhs.atom_info.size())
+                    return false;
+                for (unsigned i = 0, sz = atom_info.size(); i < sz; ++i) {
+                    if (atom_info[i] != rhs.atom_info[i])
+                        return false;
+                }
+                return true;
+            }
+            bool operator!= (const Literal_Information &rhs) const {
+                return !(*this == rhs);
+            }
+        };
+        void collect_lit_info(Literal_Information &lit_info, literal lit) {
+            LINXI_DEBUG;
+            atom *at = atoms[lit.var()];
+            if (at == nullptr || !at->is_ineq_atom()) {
+                lit_info.hash_value = lit.to_uint();
+            }
+            else {
+                lit_info.atom_info.resize(1);
+                collect_atom_info(lit_info.atom_info[0], to_ineq_atom(at));
+                lit_info.hash_value = lit_info.atom_info[0].hash_value;
+            }
+        }
+        struct Clause_Information {
+            unsigned long long hash_value;
+            vector<Literal_Information> lits_info;
+            bool operator< (const Clause_Information &rhs) const {
+                return hash_value < rhs.hash_value;
+            }
+            bool operator== (const Clause_Information &rhs) const {
+                if (hash_value != rhs.hash_value)
+                    return false;
+                if (lits_info.size() != rhs.lits_info.size())
+                    return false;
+                for (unsigned i = 0, sz = lits_info.size(); i < sz; ++i) {
+                    if (lits_info[i] != rhs.lits_info[i])
+                        return false;
+                }
+                return true;
+            }
+            bool operator!= (const Clause_Information &rhs) const {
+                return !(*this == rhs);
+            }
+        };
+        unsigned long long CLA_BASE = 9973;
+        void collect_cla_info(Clause_Information &cla_info, clause *cla) {
+            LINXI_DEBUG;
+            unsigned sz = cla->size();
+            cla_info.lits_info.resize(sz);
+            for (unsigned i = 0; i < sz; ++i) {
+                literal lit = (*cla)[i];
+                collect_lit_info(cla_info.lits_info[i], lit);
+            }
+            cla_info.hash_value = 0;
+            std::sort(cla_info.lits_info.begin(), cla_info.lits_info.end());
+            for (unsigned i = 0; i < sz; ++i) {
+                cla_info.hash_value = cla_info.hash_value*CLA_BASE + cla_info.lits_info[i].hash_value;
+            }
+        }
+        
+        void collect_clas_info(vector<Clause_Information> &clas_info) {
+            LINXI_DEBUG;
+            unsigned sz = clauses.size();
+            clas_info.resize(sz);
+            for (unsigned i = 0; i < sz; ++i) {
+                collect_cla_info(clas_info[i], clauses[i]);
+            }
+            std::sort(clas_info.begin(), clas_info.end());
+            if (!is_check) {
+                for (unsigned i = 0; i < arith_var_num; ++i) {
+                    std::sort(vars_occur[i].begin(), vars_occur[i].begin());
+                }
+            }
+        }
+        vector<Clause_Information> ori_clas_info;
+        imp(pmanager &_pm, unsynch_mpq_manager &_qm, const clause_vector &_clauses, const atom_vector &_atoms, const bool_vector &_is_int, const unsigned &_arith_var_num) : 
+            // sol(_sol),
+            pm(_pm),
+            qm(_qm),
+            clauses(_clauses),
+            atoms(_atoms),
+            is_int(_is_int),
+            arith_var_num(_arith_var_num),
+            is_check(false) {
+            vars_occur.resize(arith_var_num);
+            collect_clas_info(ori_clas_info);
+            // vars_hash.resize(arith_var_num, 0);
+        }
+        vector<Clause_Information> check_clas_info;
+        bool check_occur_same(var x, var y) {
+            if (vars_occur[x].size() != vars_occur[y].size())
+                return false;
+            for (unsigned i = 0, sz = vars_occur[x].size(); i < sz; ++i) {
+                if (vars_occur[x][i] != vars_occur[y][i])
+                    return false;
+            }
+            return true;
+        }
+        bool check_symmetry(var x, var y) {
+            if (!check_occur_same(x, y)) {
+                return false;
+            }
+            is_check = true;
+            tx = x, ty = y;
+            collect_clas_info(check_clas_info);
+            for (unsigned i = 0, sz = clauses.size(); i < sz; ++i) {
+                if (ori_clas_info[i] != check_clas_info[i])
+                    return false;
+            }
+            return true;
+        }
+    };
+    Symmetry_Checker::Symmetry_Checker(pmanager &_pm, unsynch_mpq_manager &_qm, const clause_vector &_clauses, const atom_vector &_atoms, const bool_vector &_is_int, const unsigned &_arith_var_num) {
+        LINXI_DEBUG;
+        // m_imp = alloc(imp, _sol, _pm, _am, _clauses, _learned, _atoms, _arith_var_num);
+        m_imp = alloc(imp, _pm, _qm, _clauses, _atoms, _is_int, _arith_var_num);
+    }
+    Symmetry_Checker::~Symmetry_Checker() {
+        LINXI_DEBUG;
+        dealloc(m_imp);
+    }
+    // bool Symmetry_Checker::operator()() {
+    //     LINXI_DEBUG;
+        
+    // }
+    bool Symmetry_Checker::check_symmetry(var x, var y) {
+        return m_imp->check_symmetry(x, y);
+    }
+}

src/nlsat/nlsat_symmetry_checker.h

@@ -0,0 +1,13 @@
+#include "nlsat/nlsat_clause.h"
+
+namespace nlsat {
+    class Symmetry_Checker {
+        struct imp;
+        imp *  m_imp;
+    public:
+        // Simple_Checker(solver &_sol, pmanager &_pm, anum_manager &_am, const clause_vector &_clauses, clause_vector &_learned, const atom_vector &_atoms, const unsigned &_arith_var_num);
+        Symmetry_Checker(pmanager &_pm, unsynch_mpq_manager &_qm, const clause_vector &_clauses, const atom_vector &_atoms, const bool_vector &_is_int, const unsigned &_arith_var_num);
+        ~Symmetry_Checker();
+        bool check_symmetry(var x, var y);
+    };
+}

src/nlsat/nlsat_variable_ordering_strategy.cpp

@@ -0,0 +1,282 @@
+#include "nlsat/nlsat_variable_ordering_strategy.h"
+
+namespace nlsat {
+    struct VOS_Var_Info_Collector::imp {
+        pmanager &          pm;
+        atom_vector const & m_atoms;
+        unsigned num_vars;
+        Variable_Ordering_Strategy_Type m_vos_type;
+
+        /** Maximum degree of this variable. */
+        unsigned_vector m_max_degree;
+        /** Sum of degrees of this variable within all polynomials. */
+        unsigned_vector m_sum_poly_degree;
+        /** Number of polynomials that contain this variable. */
+        unsigned_vector m_num_polynomials;
+        
+        /** Maximum degree of the leading coefficient of this variable. */
+        unsigned_vector m_max_lc_degree;
+        /** Maximum of total degrees of terms that contain this variable. */
+        unsigned_vector m_max_terms_tdegree;
+        /** Sum of degrees of this variable within all terms. */
+        unsigned_vector m_sum_term_degree;
+        /** Number of terms that contain this variable. */
+        unsigned_vector m_num_terms;
+
+        
+        unsigned_vector m_num_uni;
+        numeral_vector m_coeffs;
+        
+
+        imp(pmanager & _pm, atom_vector const & atoms, unsigned _num_vars, unsigned _vos_type):
+            pm(_pm),
+            m_atoms(atoms),
+            num_vars(_num_vars),
+            m_vos_type(Variable_Ordering_Strategy_Type(_vos_type)) {
+            
+            m_max_degree.resize(num_vars, 0);
+            m_sum_poly_degree.resize(num_vars, 0);
+            m_num_polynomials.resize(num_vars, 0);
+
+            if (m_vos_type != ONLYPOLY) {
+                m_max_lc_degree.resize(num_vars, 0);
+                m_max_terms_tdegree.resize(num_vars, 0);
+                m_sum_term_degree.resize(num_vars, 0);
+                m_num_terms.resize(num_vars, 0);
+
+                
+                m_num_uni.resize(num_vars, 0);
+                m_coeffs.resize(num_vars, 0);
+                
+            }
+        }
+
+        void collect(monomial * m) {
+            unsigned mdeg = 0;
+            for (unsigned i = 0, sz = pm.size(m); i < sz; ++i) {
+                var x = pm.get_var(m, i);
+                mdeg += pm.degree_of(m, x);
+                ++m_num_terms[x];
+            }
+
+            for (unsigned i = 0, sz = pm.size(m); i < sz; ++i) {
+                var x = pm.get_var(m, i);
+                m_sum_term_degree[x] += mdeg;
+                if (mdeg > m_max_terms_tdegree[x])
+                    m_max_terms_tdegree[x] = mdeg;
+                unsigned lc_deg = mdeg - pm.degree_of(m, x);
+                if (lc_deg > m_max_lc_degree[x])
+                    m_max_lc_degree[x] = lc_deg;
+            }
+        }
+
+        void collect(poly * p) {
+            var_vector vec_vars;
+            pm.vars(p, vec_vars);
+
+            if (m_vos_type == UNIVARIATE) {
+                if (vec_vars.size() == 1)
+                    ++m_num_uni[vec_vars[0]];
+            }
+            
+            for (unsigned i = 0, sz = vec_vars.size(); i < sz; ++i) {
+                var x = vec_vars[i];
+                unsigned k = pm.degree(p, x);
+                ++m_num_polynomials[x];
+                m_sum_poly_degree[x] += k;
+                if (k > m_max_degree[x])
+                    m_max_degree[x] = k;
+                
+                if (m_vos_type == FEATURE){
+                    for (unsigned kl = 0; kl <= k; kl++) {
+                        scoped_numeral curr(pm.m());
+                        if (pm.const_coeff(p, x, kl, curr)) {
+                            pm.m().abs(curr);
+                            if (pm.m().gt(curr, m_coeffs[x])) {
+                                pm.m().set(m_coeffs[x], curr);
+                            }
+                        }
+                    }
+                }
+                
+            }
+            
+            if (m_vos_type != ONLYPOLY && m_vos_type != UNIVARIATE){
+                for (unsigned i = 0, sz = pm.size(p); i < sz; ++i) {
+                    collect(pm.get_monomial(p, i));
+                }
+            }
+        }
+
+        void collect(literal l) {
+            bool_var b = l.var();
+            atom * a = m_atoms[b];
+            if (a == nullptr)
+                return;
+            if (a->is_ineq_atom()) {
+                unsigned sz = to_ineq_atom(a)->size();
+                for (unsigned i = 0; i < sz; i++) {
+                    collect(to_ineq_atom(a)->p(i));
+                }
+            }
+            else {
+                collect(to_root_atom(a)->p());
+            }
+        }
+        
+        void collect(clause const & c) {
+            unsigned sz = c.size();
+            for (unsigned i = 0; i < sz; i++) 
+                collect(c[i]);
+        }
+
+        void collect(clause_vector const & cs) {
+            unsigned sz = cs.size();
+            for (unsigned i = 0; i < sz; i++) 
+                collect(*(cs[i]));
+        }
+
+        
+       struct univariate_reorder_lt {
+            VOS_Var_Info_Collector::imp const *m_info;
+            univariate_reorder_lt(VOS_Var_Info_Collector::imp const *info):m_info(info) {}
+            bool operator()(var x, var y) const {
+                if (m_info->m_num_uni[x] != m_info->m_num_uni[y])
+                    return m_info->m_num_uni[x] > m_info->m_num_uni[y];
+                return x < y;
+            }
+        };
+
+        struct feature_reorder_lt {
+            VOS_Var_Info_Collector::imp const *m_info;
+            feature_reorder_lt(VOS_Var_Info_Collector::imp const * info): m_info(info){}
+            bool operator()(var x, var y) const {
+                if (m_info->m_max_degree[x] != m_info->m_max_degree[y])
+                    return m_info->m_max_degree[x] > m_info->m_max_degree[y];
+                if (m_info->m_max_terms_tdegree[x] != m_info->m_max_terms_tdegree[y])
+                    return m_info->m_max_terms_tdegree[x] > m_info->m_max_terms_tdegree[y];
+                if (!m_info->pm.m().eq(m_info->m_coeffs[x], m_info->m_coeffs[y])) {
+                    return m_info->pm.m().lt(m_info->m_coeffs[x], m_info->m_coeffs[y]);
+                }
+                return x < y;
+            }
+        };
+        struct brown_reorder_lt {
+            VOS_Var_Info_Collector::imp const *m_info;
+            brown_reorder_lt(VOS_Var_Info_Collector::imp const *info):m_info(info) {}
+            bool operator()(var x, var y) const {
+                // if (a.max_degree != b.max_degree)
+                //     return a.max_degree > b.max_degree;
+                // if (a.max_terms_tdegree != b.max_terms_tdegree)
+                //     return a.max_terms_tdegree > b.max_terms_tdegree;
+                // return a.num_terms > b.num_terms;
+                if (m_info->m_max_degree[x] != m_info->m_max_degree[y])
+                    return m_info->m_max_degree[x] > m_info->m_max_degree[y];
+                if (m_info->m_max_terms_tdegree[x] != m_info->m_max_terms_tdegree[y])
+                    return m_info->m_max_terms_tdegree[x] > m_info->m_max_terms_tdegree[y];
+                if (m_info->m_num_terms[x] != m_info->m_num_terms[y])
+                    return m_info->m_num_terms[x] > m_info->m_num_terms[y];
+                return x < y;
+            }
+        };
+        struct triangular_reorder_lt {
+            const VOS_Var_Info_Collector::imp *m_info;
+            triangular_reorder_lt(VOS_Var_Info_Collector::imp const *info):m_info(info) {}
+            bool operator()(var x, var y) const {
+                // if (a.max_degree != b.max_degree)
+                //     return a.max_degree > b.max_degree;
+                // if (a.max_lc_degree != b.max_lc_degree)
+                //     return a.max_lc_degree > b.max_lc_degree;
+                // return a.sum_poly_degree > b.sum_poly_degree;
+                if (m_info->m_max_degree[x] != m_info->m_max_degree[y])
+                    return m_info->m_max_degree[x] > m_info->m_max_degree[y];
+                if (m_info->m_max_lc_degree[x] != m_info->m_max_lc_degree[y])
+                    return m_info->m_max_lc_degree[x] > m_info->m_max_lc_degree[y];
+                if (m_info->m_sum_poly_degree[x] != m_info->m_sum_poly_degree[y])
+                    return m_info->m_sum_poly_degree[x] > m_info->m_sum_poly_degree[y];
+                return x < y;
+            }
+        };
+        struct onlypoly_reorder_lt {
+            const VOS_Var_Info_Collector::imp *m_info;
+            onlypoly_reorder_lt(VOS_Var_Info_Collector::imp const *info):m_info(info) {}
+            bool operator()(var x, var y) const {
+                // high degree first
+                if (m_info->m_max_degree[x] != m_info->m_max_degree[y])
+                    return m_info->m_max_degree[x] > m_info->m_max_degree[y];
+                // 
+                if (m_info->m_sum_poly_degree[x] != m_info->m_sum_poly_degree[y])
+                    return m_info->m_sum_poly_degree[x] > m_info->m_sum_poly_degree[y];
+                // more constrained first
+                if (m_info->m_num_polynomials[x] != m_info->m_num_polynomials[y])
+                    return m_info->m_num_polynomials[x] > m_info->m_num_polynomials[y];
+                return x < y;
+            }
+        };
+        bool check_invariant() const {return true;} // what is the invariant
+        void operator()(var_vector &perm) {
+            var_vector new_order;
+            for (var x = 0; x < num_vars; x++) {
+                new_order.push_back(x);
+            }
+            if (m_vos_type == BROWN) {
+                std::sort(new_order.begin(), new_order.end(), brown_reorder_lt(this));
+            }
+            else if (m_vos_type == TRIANGULAR) {
+                std::sort(new_order.begin(), new_order.end(), triangular_reorder_lt(this));
+            }
+            else if (m_vos_type == ONLYPOLY) {
+                std::sort(new_order.begin(), new_order.end(), onlypoly_reorder_lt(this));
+            }
+            
+            else if(m_vos_type == UNIVARIATE){
+                std::sort(new_order.begin(), new_order.end(), univariate_reorder_lt(this));
+            }
+            else if(m_vos_type == FEATURE){
+                std::sort(new_order.begin(), new_order.end(), feature_reorder_lt(this));
+            }
+            
+            else {
+                UNREACHABLE();
+            }
+            TRACE("linxi_reorder", 
+                tout << "new order: ";
+                for (unsigned i = 0; i < num_vars; i++) 
+                    tout << new_order[i] << " ";
+                tout << "\n";
+            );
+            perm.resize(num_vars, 0);
+            for (var x = 0; x < num_vars; x++) {
+                perm[new_order[x]] = x;
+            }
+            
+            SASSERT(check_invariant());
+        }
+        // std::ostream& display(std::ostream & out, display_var_proc const & proc) {
+        //     unsigned sz = m_num_occs.size();
+        //     for (unsigned i = 0; i < sz; i++) {
+        //         proc(out, i); out << " -> " << m_max_degree[i] << " : " << m_num_occs[i] << "\n";
+        //     }
+        //     return out;
+        // }
+
+        // std::ostream& display(std::ostream & out, display_var_proc const & proc) {
+        //     for (unsigned i = 0; i < num_vars; ++i) {
+        //         proc(out, i); out << " -> " << m_max_degree[i] << " : " << m_sum_poly_degree[i] << "\n";
+        //     }
+        //     return out;
+        // }
+    };
+    VOS_Var_Info_Collector::VOS_Var_Info_Collector(pmanager & _pm, atom_vector const & _atoms, unsigned _num_vars, unsigned _vos_type) {
+        m_imp = alloc(imp, _pm, _atoms, _num_vars, _vos_type);
+    }
+    VOS_Var_Info_Collector::~VOS_Var_Info_Collector() {
+        dealloc(m_imp);
+    }
+    void VOS_Var_Info_Collector::collect(clause_vector const & cs) {
+        m_imp->collect(cs);
+    }
+    void VOS_Var_Info_Collector::operator()(var_vector &perm) {
+        m_imp->operator()(perm);
+    }
+}

src/nlsat/nlsat_variable_ordering_strategy.h

@@ -0,0 +1,27 @@
+#include "nlsat/nlsat_clause.h"
+
+
+#include "math/polynomial/algebraic_numbers.h"
+#include "math/polynomial/polynomial.h"
+
+
+namespace nlsat {
+    
+    typedef polynomial::manager::scoped_numeral scoped_numeral;
+    typedef polynomial::manager::numeral_vector numeral_vector;
+    
+
+    // enum Variable_Ordering_Strategy_Type {NONE = 0, BROWN, TRIANGULAR, ONLYPOLY};
+    
+    enum Variable_Ordering_Strategy_Type {NONE = 0, BROWN, TRIANGULAR, ONLYPOLY, UNIVARIATE, FEATURE, ROOT};
+    
+    class VOS_Var_Info_Collector {
+        struct imp;
+        imp *  m_imp;
+    public:
+        VOS_Var_Info_Collector(pmanager & _pm, atom_vector const & atoms, unsigned _num_vars, unsigned _vos_type);
+        ~VOS_Var_Info_Collector();
+        void operator()(var_vector &perm);
+        void collect(clause_vector const & cs);
+    };
+}