diff --git a/gtsam/discrete/Signature.cpp b/gtsam/discrete/Signature.cpp
index bc045e8c2..17f3b52d6 100644
--- a/gtsam/discrete/Signature.cpp
+++ b/gtsam/discrete/Signature.cpp
@@ -16,56 +16,16 @@
  * @date Feb 27, 2011
  */
 
-#include <sstream>
-
+#include "gtsam/discrete/SignatureParser.h"
 #include "Signature.h"
 
-#include <boost/spirit/include/qi.hpp> // for parsing
-#include <boost/spirit/include/phoenix.hpp> // for qi::_val
+#include <sstream>
+#include <cassert>
 
 namespace gtsam {
 
   using namespace std;
 
-  namespace qi = boost::spirit::qi;
-  namespace ph = boost::phoenix;
-
-  // parser for strings of form "99/1 80/20" etc...
-  namespace parser {
-    typedef string::const_iterator It;
-    using boost::phoenix::val;
-    using boost::phoenix::ref;
-    using boost::phoenix::push_back;
-
-    // Special rows, true and false
-    Signature::Row F{1, 0}, T{0, 1};  
-
-    // Special tables (inefficient, but do we care for user input?)
-    Signature::Table logic(bool ff, bool ft, bool tf, bool tt) {
-      Signature::Table t(4);
-      t[0] = ff ? T : F;
-      t[1] = ft ? T : F;
-      t[2] = tf ? T : F;
-      t[3] = tt ? T : F;
-      return t;
-    }
-
-    struct Grammar {
-      qi::rule<It, qi::space_type, Signature::Table()> table, or_, and_, rows;
-      qi::rule<It, Signature::Row()> true_, false_, row;
-      Grammar() {
-        table = or_ | and_ | rows;
-        or_ = qi::lit("OR")[qi::_val = logic(false, true, true, true)];
-        and_ = qi::lit("AND")[qi::_val = logic(false, false, false, true)];
-        rows = +(row | true_ | false_);
-        row = qi::double_ >> +("/" >> qi::double_);
-        true_ = qi::lit("T")[qi::_val = T];
-        false_ = qi::lit("F")[qi::_val = F];
-      }
-    } grammar;
-
-  } // \namespace parser
-
   ostream& operator <<(ostream &os, const Signature::Row &row) {
     os << row[0];
     for (size_t i = 1; i < row.size(); i++)
@@ -139,9 +99,7 @@ namespace gtsam {
   Signature& Signature::operator=(const string& spec) {
     spec_ = spec;
     Table table;
-    parser::It f = spec.begin(), l = spec.end();
-    bool success =
-        qi::phrase_parse(f, l, parser::grammar.table, qi::space, table);
+    bool success = gtsam::SignatureParser::parse(spec, table);
     if (success) {
       for (Row& row : table) normalize(row);
       table_ = table;
diff --git a/gtsam/discrete/SignatureParser.cpp b/gtsam/discrete/SignatureParser.cpp
new file mode 100644
index 000000000..cf073595b
--- /dev/null
+++ b/gtsam/discrete/SignatureParser.cpp
@@ -0,0 +1,112 @@
+#include <gtsam/discrete/SignatureParser.h>
+
+#include <algorithm>
+#include <iterator>
+#include <sstream>
+
+namespace gtsam {
+
+inline static std::vector<double> ParseTrueRow() { return {0, 1}; }
+
+inline static std::vector<double> ParseFalseRow() { return {1, 0}; }
+
+inline static SignatureParser::Table ParseOr() {
+  return {ParseFalseRow(), ParseTrueRow(), ParseTrueRow(), ParseTrueRow()};
+}
+
+inline static SignatureParser::Table ParseAnd() {
+  return {ParseFalseRow(), ParseFalseRow(), ParseFalseRow(), ParseTrueRow()};
+}
+
+bool static ParseConditional(const std::string& token, std::vector<double>& row) {
+  // Expect something like a/b/c
+  std::istringstream iss2(token);
+  try {
+    // if the string has no / then return false
+    if (std::count(token.begin(), token.end(), '/') == 0) return false;
+    // split the word on the '/' character
+    for (std::string s; std::getline(iss2, s, '/');) {
+      // can throw exception
+      row.push_back(std::stod(s));
+    }
+  } catch (...) {
+    return false;
+  }
+  return true;
+}
+
+void static ParseConditionalTable(const std::vector<std::string>& tokens, SignatureParser::Table& table) {
+  // loop over the words
+  // for each word, split it into doubles using a stringstream
+  for (const auto& word : tokens) {
+    // If the string word is F or T then the row is {0,1} or {1,0} respectively
+    if (word == "F") {
+      table.push_back(ParseFalseRow());
+    } else if (word == "T") {
+      table.push_back(ParseTrueRow());
+    } else {
+      // Expect something like a/b/c
+      std::vector<double> row;
+      if (!ParseConditional(word, row)) {
+        // stop parsing if we encounter an error
+        return;
+      }
+      table.push_back(row);
+    }
+  }
+}
+
+std::vector<std::string> static Tokenize(const std::string& str) {
+  std::istringstream iss(str);
+  std::vector<std::string> tokens;
+  for (std::string s; iss >> s;) {
+    tokens.push_back(s);
+  }
+  return tokens;
+}
+
+bool SignatureParser::parse(const std::string& str, Table& table) {
+  // check if string is just whitespace
+  if (std::all_of(str.begin(), str.end(), isspace)) {
+    return false;
+  }
+
+  // return false if the string is empty
+  if (str.empty()) {
+    return false;
+  }
+
+  // tokenize the str on whitespace
+  std::vector<std::string> tokens = Tokenize(str);
+
+  // if the first token is "OR", return the OR table
+  if (tokens[0] == "OR") {
+    // if there are more tokens, return false
+    if (tokens.size() > 1) {
+      return false;
+    }
+    table = ParseOr();
+    return true;
+  }
+
+  // if the first token is "AND", return the AND table
+  if (tokens[0] == "AND") {
+    // if there are more tokens, return false
+    if (tokens.size() > 1) {
+      return false;
+    }
+    table = ParseAnd();
+    return true;
+  }
+
+  // otherwise then parse the conditional table
+  ParseConditionalTable(tokens, table);
+  // return false if the table is empty
+  if (table.empty()) {
+    return false;
+  }
+  // the boost::phoenix parser did not return an error if we could not fully parse a string
+  // it just returned whatever it could parse
+  return true;
+}
+}  // namespace gtsam
diff --git a/gtsam/discrete/SignatureParser.h b/gtsam/discrete/SignatureParser.h
new file mode 100644
index 000000000..a4a9f05f5
--- /dev/null
+++ b/gtsam/discrete/SignatureParser.h
@@ -0,0 +1,30 @@
+/**
+ * This is a simple parser that replaces the boost spirit parser. It is
+ * meant to parse strings like "1/1 2/3 1/4". Every word of the form "a/b/c/..."
+ * should be parsed as a row, and the rows should be stored in a table.
+ * The elements of the row will be doubles.
+ * The table is a vector of rows. The row is a vector of doubles.
+ * The parser should be able to parse the following strings:
+ * "1/1 2/3 1/4": {{1,1},{2,3},{1,4}}
+ * "1/1 2/3 1/4 1/1 2/3 1/4" : {{1,1},{2,3},{1,4},{1,1},{2,3},{1,4}}
+ * "1/2/3 2/3/4 1/2/3 2/3/4 1/2/3 2/3/4 1/2/3 2/3/4 1/2/3" : {{1,2,3},{2,3,4},{1,2,3},{2,3,4},{1,2,3},{2,3,4},{1,2,3},{2,3,4},{1,2,3}}
+ * If the string has unparseable elements, the parser should parse whatever it can
+ * "1/2 sdf" : {{1,2}}
+ * It should return false if the string is empty.
+ * "": false
+ * We should return false if the rows are not of the same size.
+ */
+
+#pragma once
+#include <iostream>
+#include <string>
+#include <vector>
+
+namespace gtsam {
+namespace SignatureParser {
+typedef std::vector<double> Row;
+typedef std::vector<Row> Table;
+
+bool parse(const std::string& str, Table& table);
+};  // namespace SignatureParser
+}  // namespace gtsam
diff --git a/gtsam/discrete/tests/testSignatureParser.cpp b/gtsam/discrete/tests/testSignatureParser.cpp
new file mode 100644
index 000000000..017b8e70c
--- /dev/null
+++ b/gtsam/discrete/tests/testSignatureParser.cpp
@@ -0,0 +1,97 @@
+/**
+ * Unit tests for the SimpleParser class.
+ * @file testSimpleParser.cpp
+ */
+
+#include <gtsam/base/TestableAssertions.h>
+#include <gtsam/discrete/SignatureParser.h>
+#include <CppUnitLite/TestHarness.h>
+
+bool compare_tables(const gtsam::SignatureParser::Table& table1,
+                    const gtsam::SignatureParser::Table& table2) {
+  if (table1.size() != table2.size()) {
+    return false;
+  }
+  for (size_t i = 0; i < table1.size(); ++i) {
+    if (table1[i].size() != table2[i].size()) {
+      return false;
+    }
+    for (size_t j = 0; j < table1[i].size(); ++j) {
+      if (table1[i][j] != table2[i][j]) {
+        return false;
+      }
+    }
+  }
+  return true;
+}
+
+// Simple test case
+TEST(SimpleParser, simple) {
+  gtsam::SignatureParser::Table table, expectedTable;
+  expectedTable = {{1, 1}, {2, 3}, {1, 4}};
+  bool ret = gtsam::SignatureParser::parse("1/1 2/3 1/4", table);
+  EXPECT(ret);
+  // compare the tables
+  EXPECT(compare_tables(table, expectedTable));
+}
+
+// Test case with each row having 3 elements
+TEST(SimpleParser, three_elements) {
+  gtsam::SignatureParser::Table table, expectedTable;
+  expectedTable = {{1, 1, 1}, {2, 3, 2}, {1, 4, 3}};
+  bool ret = gtsam::SignatureParser::parse("1/1/1 2/3/2 1/4/3", table);
+  EXPECT(ret);
+  // compare the tables
+  EXPECT(compare_tables(table, expectedTable));
+}
+
+// A test case to check if we can parse a signarue with 'T' and 'F'
+TEST(SimpleParser, TandF) {
+  gtsam::SignatureParser::Table table, expectedTable;
+  expectedTable = {{1,0}, {1,0}, {1,0}, {0,1}};
+  bool ret = gtsam::SignatureParser::parse("F F F T", table);
+  EXPECT(ret);
+  // compare the tables
+  EXPECT(compare_tables(table, expectedTable));
+}
+
+// A test to parse {F F F 1}
+TEST(SimpleParser, FFF1) {
+  gtsam::SignatureParser::Table table, expectedTable;
+  expectedTable = {{1,0}, {1,0}, {1,0}};
+  // should ignore the last 1
+  bool ret = gtsam::SignatureParser::parse("F F F 1", table);
+  EXPECT(ret);
+  // compare the tables
+  EXPECT(compare_tables(table, expectedTable));
+}
+
+// Expect false if the string is empty
+TEST(SimpleParser, empty_string) {
+  gtsam::SignatureParser::Table table;
+  bool ret = gtsam::SignatureParser::parse("", table);
+  EXPECT(!ret);
+}
+
+
+// Expect false if jibberish
+TEST(SimpleParser, jibberish) {
+  gtsam::SignatureParser::Table table;
+  bool ret = gtsam::SignatureParser::parse("sdf 22/3", table);
+  EXPECT(!ret);
+}
+
+// If jibberish is in the middle, it should still parse the rest
+TEST(SimpleParser, jibberish_in_middle) {
+  gtsam::SignatureParser::Table table, expectedTable;
+  expectedTable = {{1, 1}, {2, 3}};
+  bool ret = gtsam::SignatureParser::parse("1/1 2/3 sdf 1/4", table);
+  EXPECT(ret);
+  // compare the tables
+  EXPECT(compare_tables(table, expectedTable));
+}
+
+int main() {
+  TestResult tr;
+  return TestRegistry::runAllTests(tr);
+}