diff --git a/scripts/release.yml b/scripts/release.yml
index e21a99bcf..628563e5e 100644
--- a/scripts/release.yml
+++ b/scripts/release.yml
@@ -78,7 +78,7 @@ stages:
       vmImage: "ubuntu-latest"
     container: "quay.io/pypa/manylinux2010_x86_64:latest"
     variables:
-      python: "/opt/python/cp35-cp35m/bin/python"
+      python: "/opt/python/cp37-cp37m/bin/python"
     steps:
     - task: PythonScript@0
       displayName: Build
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 404d5d521..75a12cdd9 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -37,7 +37,6 @@ endforeach()
 add_subdirectory(util)
 add_subdirectory(math/polynomial)
 add_subdirectory(math/dd)
-add_subdirectory(math/polysat)
 add_subdirectory(math/hilbert)
 add_subdirectory(math/simplex)
 add_subdirectory(math/automata)
diff --git a/src/api/julia/z3jl.cpp b/src/api/julia/z3jl.cpp
index d0ad1b152..ccb2f7d07 100644
--- a/src/api/julia/z3jl.cpp
+++ b/src/api/julia/z3jl.cpp
@@ -216,7 +216,6 @@ JLCXX_MODULE define_julia_module(jlcxx::Module &m)
         .MM(expr, is_string_value)
         .MM(expr, get_escaped_string)
         .MM(expr, get_string)
-        .MM(expr, fpa_rounding_mode_sort)
         .MM(expr, decl)
         .MM(expr, num_args)
         .MM(expr, arg)
diff --git a/src/math/lp/lar_solver.cpp b/src/math/lp/lar_solver.cpp
index 0837a7b5d..b31713094 100644
--- a/src/math/lp/lar_solver.cpp
+++ b/src/math/lp/lar_solver.cpp
@@ -1719,7 +1719,7 @@ namespace lp {
 
     void lar_solver::subst_known_terms(lar_term* t) {
         std::set<unsigned> seen_terms;
-        for (const auto&p : *t) {
+        for (auto p : *t) {
             auto j = p.column();
             if (this->column_corresponds_to_term(j)) {
                 seen_terms.insert(j);
@@ -1730,10 +1730,10 @@ namespace lp {
             seen_terms.erase(j);
             auto tj = this->m_var_register.local_to_external(j);
             auto& ot = this->get_term(tj);
-            for(const auto&  p : ot){
-              if (this->column_corresponds_to_term(p.column())) {
-                 seen_terms.insert(p.column());
-              }   
+            for (auto p : ot){
+                if (this->column_corresponds_to_term(p.column())) {
+                    seen_terms.insert(p.column());
+                }   
             }
             t->subst_by_term(ot, j);
         }
diff --git a/src/math/polysat/CMakeLists.txt b/src/math/polysat/CMakeLists.txt
deleted file mode 100644
index 89382f290..000000000
--- a/src/math/polysat/CMakeLists.txt
+++ /dev/null
@@ -1,7 +0,0 @@
-z3_add_component(polysat
-  SOURCES
-    polysat.cpp
-  COMPONENT_DEPENDENCIES
-    util
-    dd
-)
diff --git a/src/math/polysat/polysat.cpp b/src/math/polysat/polysat.cpp
deleted file mode 100644
index b8080cb93..000000000
--- a/src/math/polysat/polysat.cpp
+++ /dev/null
@@ -1,432 +0,0 @@
-/*++
-Copyright (c) 2021 Microsoft Corporation
-
-Module Name:
-
-    polysat
-
-Abstract:
-
-    Polynomial solver for modular arithmetic.
-
-Author:
-
-    Nikolaj Bjorner (nbjorner) 2021-03-19
-
---*/
-
-#include "math/polysat/polysat.h"
-
-namespace polysat {
-
-    std::ostream& constraint::display(std::ostream& out) const {
-        return out << "constraint";
-    }
-    
-    std::ostream& linear::display(std::ostream& out) const {
-        return out << "linear";
-    }
-
-    std::ostream& mono::display(std::ostream& out) const {
-        return out << "mono";
-    }
-
-    dd::pdd_manager& solver::sz2pdd(unsigned sz) {
-        m_pdd.reserve(sz + 1);
-        if (!m_pdd[sz])
-            m_pdd.set(sz, alloc(dd::pdd_manager, 1000));
-        return *m_pdd[sz];
-    }
-
-    bool solver::is_viable(unsigned var, rational const& val) {
-        bdd b = m_viable[var];
-        for (unsigned k = size(var); k-- > 0 && !b.is_false(); ) 
-            b &= val.get_bit(k) ? m_bdd.mk_var(k) : m_bdd.mk_nvar(k);
-        return !b.is_false();
-    }
-
-    struct solver::del_var : public trail {
-        solver& s;
-        del_var(solver& s): s(s) {}
-        void undo() override { s.do_del_var(); }
-    };
-
-    struct solver::del_constraint : public trail {
-        solver& s;
-        del_constraint(solver& s): s(s) {}
-        void undo() override { s.do_del_constraint(); }
-    };
-
-    struct solver::var_unassign : public trail {
-        solver& s;
-        var_unassign(solver& s): s(s) {}
-        void undo() override { s.do_var_unassign(); }
-    };
-
-    
-    solver::solver(trail_stack& s): 
-        m_trail(s),
-        m_bdd(1000),
-        m_free_vars(m_activity) {
-    }
-
-    solver::~solver() {}
-    
-    lbool solver::check_sat() { 
-        return l_undef;
-    }
-        
-    unsigned solver::add_var(unsigned sz) {
-        unsigned v = m_viable.size();
-        m_value.push_back(rational::zero());
-        m_justification.push_back(justification::unassigned());
-        m_viable.push_back(m_bdd.mk_true());
-        m_vdeps.push_back(m_dep_manager.mk_empty());
-        m_cjust.push_back(constraints());
-        m_watch.push_back(ptr_vector<constraint>());
-        m_activity.push_back(0);
-        m_vars.push_back(sz2pdd(sz).mk_var(v));
-        m_size.push_back(sz);
-        m_trail.push(del_var(*this));
-        return v;
-    }
-
-    void solver::do_del_var() {
-        // TODO also remove v from all learned constraints.
-        unsigned v = m_viable.size() - 1;
-        m_free_vars.del_var_eh(v);
-        m_viable.pop_back();
-        m_vdeps.pop_back();
-        m_cjust.pop_back();
-        m_value.pop_back();
-        m_justification.pop_back();
-        m_watch.pop_back();
-        m_activity.pop_back();
-        m_vars.pop_back();
-        m_size.pop_back();
-    }
-
-    void solver::do_del_constraint() {
-        // TODO rewrite to allow for learned constraints
-        // so have to gc these.
-        constraint& c = *m_constraints.back();
-        if (c.vars().size() > 0)
-            erase_watch(c.vars()[0], c);
-        if (c.vars().size() > 1)
-            erase_watch(c.vars()[1], c);
-        m_constraints.pop_back();
-    }
-
-    void solver::do_var_unassign() {
-        unsigned v = m_search.back();
-        m_justification[v] = justification::unassigned();
-        m_free_vars.unassign_var_eh(v);
-    }
-
-    void solver::add_eq(pdd const& p, unsigned dep) {
-        //
-        // TODO reduce p using assignment (at current level, 
-        // assuming constraint is removed also at current level).
-        // 
-        constraint* c = constraint::eq(p, m_dep_manager.mk_leaf(dep));
-        m_constraints.push_back(c);
-        auto const& vars = c->vars();
-        if (vars.size() > 0) 
-            m_watch[vars[0]].push_back(c);
-        if (vars.size() > 1) 
-            m_watch[vars[1]].push_back(c);
-        m_trail.push(del_constraint(*this));
-    }
-
-    void solver::add_diseq(pdd const& p, unsigned dep) {
-#if 0
-        // Basically: 
-        auto slack = add_var(p.size());
-        p = p + var(slack);
-        add_eq(p, dep);
-        m_viable[slack] &= slack != 0;
-#endif
-    }
-
-    void solver::add_ule(pdd const& p, pdd const& q, unsigned dep) {
-        // save for later
-    }
-
-    void solver::add_sle(pdd const& p, pdd const& q, unsigned dep) {
-        // save for later
-    }
-
-    void solver::assign(unsigned var, unsigned index, bool value, unsigned dep) {
-        m_viable[var] &= value ? m_bdd.mk_var(index) : m_bdd.mk_nvar(index);
-        m_trail.push(vector_value_trail<u_dependency*, false>(m_vdeps, var));
-        m_vdeps[var] = m_dep_manager.mk_join(m_vdeps[var], m_dep_manager.mk_leaf(dep));
-        if (m_viable[var].is_false()) {
-            // TBD: set conflict
-        }
-    }
-
-    bool solver::can_propagate() {
-        return m_qhead < m_search.size() && !is_conflict();
-    }
-
-    void solver::propagate() {
-        m_trail.push(value_trail(m_qhead));
-        while (can_propagate()) 
-            propagate(m_search[m_qhead++]);
-    }
-
-    void solver::propagate(unsigned v) {
-        auto& wlist = m_watch[v];
-        unsigned i = 0, j = 0, sz = wlist.size();
-        for (; i < sz && !is_conflict(); ++i) 
-            if (!propagate(v, *wlist[i]))
-                wlist[j++] = wlist[i];
-        for (; i < sz; ++i)
-            wlist[j++] = wlist[i];
-        wlist.shrink(j);
-    }
-
-    bool solver::propagate(unsigned v, constraint& c) {
-        switch (c.kind()) {
-        case ckind_t::eq_t:
-            return propagate_eq(v, c);
-        case ckind_t::ule_t:
-        case ckind_t::sle_t:
-            NOT_IMPLEMENTED_YET();
-            return false;
-        }
-        UNREACHABLE();
-        return false;
-    }
-
-    bool solver::propagate_eq(unsigned v, constraint& c) {
-        SASSERT(c.kind() == ckind_t::eq_t);
-        SASSERT(!c.vars().empty());
-        auto var = m_vars[v].var();
-        auto& vars = c.vars();
-        unsigned idx = 0;
-        if (vars[idx] != v)
-            idx = 1;
-        SASSERT(v == vars[idx]);
-        // find other watch variable.
-        for (unsigned i = vars.size(); i-- > 2; ) {
-            if (!is_assigned(vars[i])) {
-                std::swap(vars[idx], vars[i]);
-                return true;
-            }
-        }        
-
-        vector<std::pair<unsigned, rational>> sub;
-        for (auto w : vars) 
-            if (is_assigned(w))
-                sub.push_back(std::make_pair(w, m_value[w]));
-
-        auto p = c.p().subst_val(sub);
-        if (p.is_zero()) 
-            return false;
-        if (p.is_non_zero()) {
-            // we could tag constraint to allow early substitution before 
-            // swapping watch variable in case we can detect conflict earlier.
-            set_conflict(c);
-            return false;
-        }
-
-        // one variable remains unassigned.
-        auto other_var = vars[1 - idx];
-        SASSERT(!is_assigned(other_var));
-
-        // Detect and apply unit propagation.
-            
-        if (!p.is_linear())
-            return false;
-
-        // a*x + b == 0
-        rational a = p.hi().val();
-        rational b = p.lo().val();
-        rational inv_a;
-        if (p.lo().val().is_odd()) {
-            // v1 = -b * inverse(a)
-            unsigned sz = p.power_of_2();
-            VERIFY(a.mult_inverse(sz, inv_a)); 
-            rational val = mod(inv_a * -b, rational::power_of_two(sz));
-            m_cjust[other_var].push_back(&c);
-            m_trail.push(push_back_vector(m_cjust[other_var]));
-            propagate(other_var, val, justification::propagation(m_level));
-            return false;
-        }
-
-        // TBD
-        // constrain viable using condition on x
-        // 2*x + 2 == 0 mod 4 => x is odd
-        
-        return false;
-    }
-
-    void solver::propagate(unsigned var, rational const& val, justification const& j) {
-        SASSERT(j.is_propagation());
-        if (is_viable(var, val)) 
-            assign_core(var, val, j);        
-        else 
-            set_conflict(*m_cjust[var].back());
-}
-
-    void solver::inc_level() {
-        m_trail.push(value_trail(m_level));
-        ++m_level;
-    }
-
-    void solver::erase_watch(unsigned v, constraint& c) {
-        if (v == UINT_MAX)
-            return;
-        auto& wlist = m_watch[v];
-        unsigned sz = wlist.size();
-        for (unsigned i = 0; i < sz; ++i) {
-            if (&c == wlist[i]) {
-                wlist[i] = wlist.back();
-                wlist.pop_back();
-                return;
-            }
-        }
-    }
-
-    void solver::decide(rational & val, unsigned& var) {
-        SASSERT(can_decide());
-        inc_level();
-        var = m_free_vars.next_var();
-        auto viable = m_viable[var];
-        SASSERT(!viable.is_false());
-        // TBD, choose some value from viable and construct val.
-        assign_core(var, val, justification::decision(m_level));
-    }
-
-    void solver::assign_core(unsigned var, rational const& val, justification const& j) {
-        SASSERT(is_viable(var, val));
-        m_trail.push(var_unassign(*this));
-        m_search.push_back(var);
-        m_value[var] = val;
-        m_justification[var] = j; 
-    }
-        
-    /**
-     * Conflict resolution.
-     * - m_conflict is a constraint infeasible in the current assignment.
-     * 1. walk m_search from top down until last variable in m_conflict.
-     * 2. resolve constraints in m_cjust to isolate lowest degree polynomials
-     *    using variable.
-     *    Use Olm-Seidl division by powers of 2 to preserve invertibility.
-     * 3. resolve conflict with result of resolution.
-     * 4. If the resulting equality is still infeasible continue, otherwise bail out
-     *    and undo the last assignment by accumulating conflict trail (but without resolution).
-     * 5. When hitting the last decision, determine whether conflict polynomial is asserting,
-     *    If so, apply propagation.
-     * 6. Otherwise, add accumulated constraints to explanation for the next viable solution, prune
-     *    viable solutions by excluding the previous guess.
-     */
-    unsigned solver::resolve_conflict(unsigned_vector& deps) {
-        SASSERT(m_conflict);
-        constraint& c = *m_conflict;
-        m_conflict = nullptr;
-        pdd p = c.p();
-        reset_marks();
-        for (auto v : c.vars())
-            set_mark(v);
-        unsigned v = UINT_MAX;
-        unsigned i = m_search.size();
-        vector<std::pair<unsigned, rational>> sub;
-        for (auto w : m_search) 
-            sub.push_back(std::make_pair(w, m_value[w]));
-
-        for (; i-- > 0; ) {
-            v = m_search[i];
-            if (!is_marked(v))
-                continue;
-            pdd q = isolate(v);
-            pdd r = resolve(v, q, p);
-            pdd rval = r.subst_val(sub);
-            if (!rval.is_non_zero())
-                goto backtrack;
-            if (r.is_val()) {
-                SASSERT(!r.is_zero());
-                // TBD: UNSAT, set conflict
-                return 0;
-            }
-            justification& j = m_justification[v];
-            if (j.is_decision()) {
-                // TBD: revert value and add constraint
-                // propagate if new value is given uniquely
-                // set conflict if viable set is empty
-                // adding r and reverting last decision.
-                break;
-            }
-            SASSERT(j.is_propagation());
-            for (auto w : r.free_vars())
-                set_mark(w);
-            p = r;
-        }
-        UNREACHABLE();
-        
-    backtrack:
-        do {
-            v = m_search[i];
-            justification& j = m_justification[v];
-            if (j.is_decision()) {
-                // TBD: flip last decision.
-            }
-        }
-        while (i-- > 0);
-        
-        return 0;
-    }
-    
-    /**
-     * resolve polynomials associated with unit propagating on v
-     * producing polynomial that isolates v to lowest degree
-     * and lowest power of 2.     
-     */
-    pdd solver::isolate(unsigned v) {
-        if (m_cjust[v].empty()) 
-            return sz2pdd(m_size[v]).zero();
-        pdd p = m_cjust[v][0]->p();
-        for (unsigned i = m_cjust[v].size(); i-- > 1; ) {
-            // TBD reduce with respect to v
-        }
-        return p;
-    }
-    
-    /**
-     * Return residue of superposing p and q with respect to v.
-     */
-    pdd solver::resolve(unsigned v, pdd const& p, pdd const& q) {
-        // TBD remove as much trace of v as possible.
-        return p;
-    }
-    
-    void solver::reset_marks() {
-        m_marks.reserve(m_vars.size());
-        m_clock++;
-        if (m_clock != 0)
-            return;
-        m_clock++;
-        m_marks.fill(0);        
-    }
-        
-    bool solver::can_learn() {
-        return false;
-    }
-
-    void solver::learn(constraint& c, unsigned_vector& deps) {
-
-    } 
-
-    void solver::learn(vector<constraint>& cs, unsigned_vector& deps) {
-
-    }
-
-    std::ostream& solver::display(std::ostream& out) const {
-        return out;
-    }
-
-
-}
-
-
diff --git a/src/math/polysat/polysat.h b/src/math/polysat/polysat.h
deleted file mode 100644
index a89941cea..000000000
--- a/src/math/polysat/polysat.h
+++ /dev/null
@@ -1,261 +0,0 @@
-/*++
-Copyright (c) 2021 Microsoft Corporation
-
-Module Name:
-
-    polysat
-
-Abstract:
-
-    Polynomial solver for modular arithmetic.
-
-Author:
-
-    Nikolaj Bjorner (nbjorner) 2021-03-19
-
---*/
-#pragma once
-
-#include "util/dependency.h"
-#include "util/trail.h"
-#include "util/lbool.h"
-#include "util/scoped_ptr_vector.h"
-#include "util/var_queue.h"
-#include "math/dd/dd_pdd.h"
-#include "math/dd/dd_bdd.h"
-
-namespace polysat {
-
-    class solver;
-    typedef dd::pdd pdd;
-    typedef dd::bdd bdd;
-
-    enum ckind_t { eq_t, ule_t, sle_t };
-
-    class constraint {
-        ckind_t m_kind;
-        pdd    m_poly;
-        pdd    m_other;
-        u_dependency* m_dep;
-        unsigned_vector m_vars;
-        constraint(pdd const& p, pdd const& q, u_dependency* dep, ckind_t k): 
-            m_kind(k), m_poly(p), m_other(q), m_dep(dep) {
-            m_vars.append(p.free_vars());
-            if (q != p) 
-                for (auto v : q.free_vars())
-                    m_vars.insert(v);                
-        }
-    public:
-        static constraint* eq(pdd const& p, u_dependency* d) { return alloc(constraint, p, p, d, ckind_t::eq_t); }
-        static constraint* ule(pdd const& p, pdd const& q, u_dependency* d) { return alloc(constraint, p, q, d, ckind_t::ule_t); }
-        ckind_t kind() const { return m_kind; }
-        pdd const &  p() const { return m_poly; }
-        pdd const &  lhs() const { return m_poly; }
-        pdd const &  rhs() const { return m_other; }
-        std::ostream& display(std::ostream& out) const;
-        u_dependency* dep() const { return m_dep; }
-        unsigned_vector& vars() { return m_vars; }
-    };
-
-    inline std::ostream& operator<<(std::ostream& out, constraint const& c) { return c.display(out); }
-
-    /**
-     * linear term is has an offset and is linear addition of variables.
-     */
-    class linear : public vector<std::pair<unsigned, rational>> {
-        rational m_offset;
-    public:
-        linear(rational const& offset): m_offset(offset) {}
-        rational const& offset() const { return m_offset; }
-        std::ostream& display(std::ostream& out) const;
-    };
-
-    inline std::ostream& operator<<(std::ostream& out, linear const& l) { return l.display(out); }
-
-    /**
-     * monomial is a list of variables and coefficient.
-     */
-    class mono : public unsigned_vector {
-        rational m_coeff;
-    public:
-        mono(rational const& coeff): m_coeff(coeff) {}
-        rational const& coeff() const { return m_coeff; }
-        std::ostream& display(std::ostream& out) const;
-    };
-
-    inline std::ostream& operator<<(std::ostream& out, mono const& m) { return m.display(out); }
-
-    /**
-     * Justification kind for a variable assignment.
-     */
-    enum justification_k { unassigned, decision, propagation };
-
-    class justification {
-        justification_k m_kind;
-        unsigned        m_level;
-        justification(justification_k k, unsigned lvl): m_kind(k), m_level(lvl) {}
-    public:
-        justification(): m_kind(justification_k::unassigned) {}
-        static justification unassigned() { return justification(justification_k::unassigned, 0); }
-        static justification decision(unsigned lvl) { return justification(justification_k::decision, lvl); }
-        static justification propagation(unsigned lvl) { return justification(justification_k::propagation, lvl); }
-        bool is_decision() const { return m_kind == justification_k::decision; }
-        bool is_unassigned() const { return m_kind == justification_k::unassigned; }
-        bool is_propagation() const { return m_kind == justification_k::propagation; }
-        justification_k kind() const { return m_kind; }
-        unsigned level() const { return m_level; }
-        std::ostream& display(std::ostream& out) const;
-    };
-
-    inline std::ostream& operator<<(std::ostream& out, justification const& j) { return j.display(out); }
-
-    class solver {
-
-        typedef ptr_vector<constraint> constraints;
-
-        trail_stack&             m_trail;
-        scoped_ptr_vector<dd::pdd_manager> m_pdd;
-        dd::bdd_manager          m_bdd;
-        u_dependency_manager     m_dep_manager;
-        var_queue                m_free_vars;
-
-        // Per constraint state
-        scoped_ptr_vector<constraint>   m_constraints;
-        // TODO: vector<constraint> m_redundant; // learned constraints
-
-        // Per variable information
-        vector<bdd>              m_viable;   // set of viable values.
-        ptr_vector<u_dependency> m_vdeps;    // dependencies for viable values
-        vector<rational>         m_value;    // assigned value
-        vector<justification>    m_justification; // justification for variable assignment
-        vector<constraints>      m_cjust;    // constraints used for justification
-        vector<constraints>      m_watch;    // watch list datastructure into constraints.
-        unsigned_vector          m_activity; 
-        vector<pdd>              m_vars;
-        unsigned_vector          m_size;     // store size of variables.
-
-        // search state that lists assigned variables
-        unsigned_vector          m_search;
-        unsigned                 m_qhead { 0 };
-        unsigned                 m_level { 0 };
-
-        // conflict state
-        constraint* m_conflict { nullptr };
-
-        unsigned size(unsigned var) const { return m_size[var]; }
-        /**
-         * check if value is viable according to m_viable.
-         */
-        bool is_viable(unsigned var, rational const& val);
-
-        /**
-         * undo trail operations for backtracking.
-         * Each struct is a subclass of trail and implements undo().
-         */
-        struct del_var;
-        struct del_constraint;
-        struct var_unassign;
-
-        void do_del_var();
-        void do_del_constraint();
-        void do_var_unassign();
-
-        dd::pdd_manager& sz2pdd(unsigned sz);
-
-        void inc_level();
-
-        void assign_core(unsigned var, rational const& val, justification const& j);
-
-        bool is_assigned(unsigned var) const { return !m_justification[var].is_unassigned(); }
-
-        void propagate(unsigned v);
-        bool propagate(unsigned v, constraint& c);
-        bool propagate_eq(unsigned v, constraint& c);
-        void propagate(unsigned var, rational const& val, justification const& j);
-        void erase_watch(unsigned v, constraint& c);
-
-        void set_conflict(constraint& c) { m_conflict = &c; }
-        void clear_conflict() { m_conflict = nullptr; }
-
-        unsigned_vector m_marks;
-        unsigned        m_clock { 0 };
-        void reset_marks();
-        bool is_marked(unsigned v) const { return m_clock == m_marks[v]; }
-        void set_mark(unsigned v) { m_marks[v] = m_clock; }
-
-        pdd isolate(unsigned v);
-        pdd resolve(unsigned v, pdd const& p, pdd const& q);
-
-        /**
-         * push / pop are used only in self-contained mode from check_sat.
-         */
-        void push() { m_trail.push_scope(); }
-        void pop(unsigned n) { m_trail.pop_scope(n); }
-
-    public:
-
-        /**
-         * to share chronology we pass an external trail stack.
-         * every update to the solver is going to be retractable
-         * by pushing an undo action on the trail stack.
-         */
-        solver(trail_stack& s);
-        ~solver();
-
-        /**
-         * Self-contained satisfiability checker.
-         * Main mode is to have external solver drive state machine.
-         */
-        lbool check_sat();
-        
-        /**
-         * Add variable with bit-size. 
-         */
-        unsigned add_var(unsigned sz);
-
-        /**
-         * Create polynomial terms
-         */
-        pdd var(unsigned v) { return m_vars[v]; }
-
-
-        /**
-         * Add polynomial constraints
-         * Each constraint is tracked by a dependency.
-         * assign sets the 'index'th bit of var.
-         */
-        void add_eq(pdd const& p, unsigned dep);
-        void add_diseq(pdd const& p, unsigned dep);
-        void add_ule(pdd const& p, pdd const& q, unsigned dep);
-        void add_sle(pdd const& p, pdd const& q, unsigned dep);
-        void assign(unsigned var, unsigned index, bool value, unsigned dep);        
-
-        /**
-         * main state transitions.
-         */
-        bool can_propagate();
-        void propagate();
-
-        bool can_decide() const { return !m_free_vars.empty(); }
-        void decide(rational & val, unsigned& var);
-
-        bool is_conflict() const { return nullptr != m_conflict; }
-        /**
-         * Return number of scopes to backtrack and core in the shape of dependencies
-         * TBD: External vs. internal mode may need different signatures.
-         */
-        unsigned resolve_conflict(unsigned_vector& deps);            
-        
-        bool can_learn();
-        void learn(constraint& c, unsigned_vector& deps); 
-        void learn(vector<constraint>& cs, unsigned_vector& deps); 
-
-        std::ostream& display(std::ostream& out) const;
-
-    };
-
-    inline std::ostream& operator<<(std::ostream& out, solver const& s) { return s.display(out); }
-
-}
-
-
diff --git a/src/smt/smt_context.cpp b/src/smt/smt_context.cpp
index d16e3a051..2c08ba860 100644
--- a/src/smt/smt_context.cpp
+++ b/src/smt/smt_context.cpp
@@ -1395,7 +1395,7 @@ namespace smt {
         SASSERT(get_bdata(v).is_enode());
         lbool val  = get_assignment(v);
         TRACE("propagate_bool_var_enode_bug", tout << "var: " << v << " #" << bool_var2expr(v)->get_id() << "\n";);
-        SASSERT(v < static_cast<int>(m_b_internalized_stack.size()));
+        SASSERT(v < m_b_internalized_stack.size());
         enode * n  = bool_var2enode(v);
 
         CTRACE("mk_bool_var", !n, tout << "No enode for " << v << "\n";);
@@ -1986,7 +1986,7 @@ namespace smt {
     void context::remove_lit_occs(clause const& cls, unsigned nbv) {
         if (!track_occs()) return;
         for (literal l : cls) {
-            if (l.var() < static_cast<int>(nbv)) 
+            if (l.var() < nbv) 
                 dec_ref(l);
         }
     }
@@ -2264,7 +2264,7 @@ namespace smt {
                     SASSERT(cls->get_num_atoms() == cls->get_num_literals());
                     for (unsigned j = 0; j < 2; j++) {
                         literal l           = cls->get_literal(j);
-                        if (l.var() < static_cast<int>(num_bool_vars)) {
+                        if (l.var() < num_bool_vars) {
                             // This boolean variable was not deleted during backtracking
                             //
                             // So, it is still a watch literal. I remove the watch, since
@@ -4096,7 +4096,7 @@ namespace smt {
                 expr * * atoms         = m_conflict_resolution->get_lemma_atoms();
                 for (unsigned i = 0; i < num_lits; i++) {
                     literal l   = lits[i];
-                    if (l.var() >= static_cast<int>(num_bool_vars)) {
+                    if (l.var() >= num_bool_vars) {
                         // This boolean variable was deleted during backtracking, it need to be recreated.
                         // Remark: atom may be a negative literal (not a). Z3 creates Boolean variables for not-gates that
                         // are nested in terms. Example: let f be a uninterpreted function from Bool -> Int.