diff --git a/src/math/realclosure/realclosure.cpp b/src/math/realclosure/realclosure.cpp
index 35a7fcedc..1e9b1ee1a 100644
--- a/src/math/realclosure/realclosure.cpp
+++ b/src/math/realclosure/realclosure.cpp
@@ -275,15 +275,15 @@ namespace realclosure {
     struct algebraic : public extension {
         polynomial   m_p;
         sign_det *   m_sign_det; //!< != 0         if m_interval constains more than one root of m_p.
-        unsigned     m_idx;      //!< != UINT_MAX  if m_sign_det != 0, in this case m_idx < m_sign_det->m_sign_conditions.size()
+        unsigned     m_sdt_idx;   //!< != UINT_MAX  if m_sign_det != 0, in this case m_sdt_idx < m_sign_det->m_sign_conditions.size()
         bool         m_real;     //!< True if the polynomial p does not depend on infinitesimal extensions.
 
-        algebraic(unsigned idx):extension(ALGEBRAIC, idx), m_sign_det(0), m_idx(0), m_real(false) {}
+        algebraic(unsigned idx):extension(ALGEBRAIC, idx), m_sign_det(0), m_sdt_idx(0), m_real(false) {}
 
         polynomial const & p() const { return m_p; }
         bool is_real() const { return m_real; }
         sign_det * sdt() const { return m_sign_det; }
-        unsigned sdt_idx() const { return m_idx; }
+        unsigned sdt_idx() const { return m_sdt_idx; }
     };
 
     struct transcendental : public extension {
@@ -445,6 +445,7 @@ namespace realclosure {
                 m_scs.append(scs.m_scs.size(), scs.m_scs.c_ptr());
                 scs.release();
             }
+            sign_condition * const * c_ptr() { return m_scs.c_ptr(); }
         };
         
         imp(unsynch_mpq_manager & qm, params_ref const & p, small_object_allocator * a):
@@ -639,6 +640,11 @@ namespace realclosure {
             cleanup(extension::INFINITESIMAL);
             return m_extensions[extension::INFINITESIMAL].size();
         }
+
+        unsigned next_algebraic_idx() {
+            cleanup(extension::ALGEBRAIC);
+            return m_extensions[extension::ALGEBRAIC].size();
+        }
         
         void set_cancel(bool f) {
             m_cancel = f;
@@ -1620,6 +1626,53 @@ namespace realclosure {
             return false;
         }
 
+        /**
+           \brief Store the polynomials in prs into the array of polynomials ps.
+        */
+        void set_array_p(array<polynomial> & ps, scoped_polynomial_seq const & prs) {
+            unsigned sz = prs.size();
+            ps.set(allocator(), sz, polynomial());
+            for (unsigned i = 0; i < sz; i++) {
+                unsigned pi_sz     = prs.size(i);
+                value * const * pi = prs.coeffs(i);
+                set_p(ps[i], pi_sz, pi);
+            }
+        }
+
+        /**
+           \brief Create a "sign determination" data-structure for an algebraic extension.
+           
+           The new object will assume the ownership of the elements stored in M and scs. 
+           M and scs will be empty after this operation.
+        */
+        sign_det * mk_sign_det(mpz_matrix & M, scoped_polynomial_seq const & prs, scoped_polynomial_seq const & qs, scoped_sign_conditions & scs) {
+            sign_det * r = new (allocator()) sign_det();
+            r->M.swap(M);
+            set_array_p(r->m_prs, prs);
+            set_array_p(r->m_qs,  qs);
+            r->m_sign_conditions.set(allocator(), scs.size(), scs.c_ptr());
+            scs.release();
+            return r;
+        }
+
+        /**
+           \brief Create a new algebraic extension
+         */
+        algebraic * mk_algebraic(unsigned p_sz, value * const * p, mpbqi const & interval, sign_det * sd, unsigned sdt_idx) {
+            unsigned idx = next_algebraic_idx();
+            algebraic * r = new (allocator()) algebraic(idx);
+            m_extensions[extension::ALGEBRAIC].push_back(r);
+            
+            set_p(r->m_p, p_sz, p);
+            set_interval(r->m_interval, interval);
+            r->m_sign_det = sd;
+            inc_ref_sign_det(sd);
+            r->m_sdt_idx  = sdt_idx;
+            r->m_real     = is_real(p_sz, p);
+
+            return r;
+        }
+
         /**
            \brief Isolate roots of p in the given interval using sign conditions to distinguish between them.
            We need this method when the polynomial contains roots that are infinitesimally close to each other.
@@ -1834,12 +1887,14 @@ namespace realclosure {
                   for (unsigned j = 0; j < prs.size(); j++) {
                       display_poly(tout, prs.size(j), prs.coeffs(j)); tout << "\n";
                   });
-
-            // TODO: create the extension objects using
-            // M_s, prs, scs, qs
-            // Remark: scs and qs are only for pretty printing
-            // For determining the signs of other polynomials in the new extension objects,
-            // we only need M_s and prs
+            SASSERT(M_s.n() == M_s.m()); SASSERT(M_s.n() == static_cast<unsigned>(num_roots));
+            sign_det * sd = mk_sign_det(M_s, prs, qs, scs);
+            for (unsigned idx = 0; idx < static_cast<unsigned>(num_roots); idx++) {
+                algebraic * a = mk_algebraic(p_sz, p, interval, sd, idx);
+                numeral r;
+                set(r, mk_rational_function_value(a));
+                roots.push_back(r);
+            }
         }
 
         /**
diff --git a/src/util/array.h b/src/util/array.h
index 6f179713f..c2358d1a4 100644
--- a/src/util/array.h
+++ b/src/util/array.h
@@ -53,11 +53,11 @@ private:
         set_data(mem, sz);
     }
 
-    void init() {
+    void init(T const & v) {
         iterator it = begin();
         iterator e  = end();
         for (; it != e; ++it) {
-            new (it) T();
+            new (it) T(v);
         }
     }
     
@@ -140,6 +140,13 @@ public:
         init(vs);
     }
 
+    template<typename Allocator>
+    void set(Allocator & a, size_t sz, T const & v = T()) {
+        SASSERT(m_data == 0);
+        allocate(a, sz);
+        init(v);
+    }
+
     size_t size() const { 
         if (m_data == 0) {
             return 0;  
@@ -181,6 +188,7 @@ public:
     void swap(array & other) {
         std::swap(m_data, other.m_data);
     }
+
 };
 
 template<typename T>