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diff --git a/boost/geometry/algorithms/detail/is_valid/linear.hpp b/boost/geometry/algorithms/detail/is_valid/linear.hpp
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+// Boost.Geometry (aka GGL, Generic Geometry Library)
+
+// Copyright (c) 2014, Oracle and/or its affiliates.
+
+// Contributed and/or modified by Menelaos Karavelas, on behalf of Oracle
+
+// Licensed under the Boost Software License version 1.0.
+// http://www.boost.org/users/license.html
+
+#ifndef BOOST_GEOMETRY_ALGORITHMS_DETAIL_IS_VALID_LINEAR_HPP
+#define BOOST_GEOMETRY_ALGORITHMS_DETAIL_IS_VALID_LINEAR_HPP
+
+#include <cstddef>
+
+#include <boost/range.hpp>
+
+#include <boost/geometry/core/closure.hpp>
+#include <boost/geometry/core/point_type.hpp>
+#include <boost/geometry/core/tags.hpp>
+
+#include <boost/geometry/util/range.hpp>
+
+#include <boost/geometry/algorithms/equals.hpp>
+#include <boost/geometry/algorithms/detail/check_iterator_range.hpp>
+#include <boost/geometry/algorithms/detail/is_valid/has_spikes.hpp>
+#include <boost/geometry/algorithms/detail/num_distinct_consecutive_points.hpp>
+
+#include <boost/geometry/algorithms/dispatch/is_valid.hpp>
+
+
+namespace boost { namespace geometry
+{
+
+#ifndef DOXYGEN_NO_DETAIL
+namespace detail { namespace is_valid
+{
+
+
+template <typename Linestring, bool AllowSpikes>
+struct is_valid_linestring
+{
+    static inline bool apply(Linestring const& linestring)
+    {
+        std::size_t num_distinct = detail::num_distinct_consecutive_points
+            <
+                Linestring,
+                3u,
+                true,
+                not_equal_to<typename point_type<Linestring>::type>
+            >::apply(linestring);
+
+        if ( num_distinct < 2u )
+        {
+            return false;
+        }
+
+        return num_distinct == 2u
+            || AllowSpikes
+            || !has_spikes<Linestring, closed>::apply(linestring);
+    }
+};
+
+
+}} // namespace detail::is_valid
+#endif // DOXYGEN_NO_DETAIL
+
+
+
+
+#ifndef DOXYGEN_NO_DISPATCH
+namespace dispatch
+{
+
+
+// A linestring is a curve.
+// A curve is 1-dimensional so it has to have at least two distinct
+// points.
+// A curve is simple if it does not pass through the same point twice,
+// with the possible exception of its two endpoints
+//
+// There is an option here as to whether spikes are allowed for linestrings; 
+// here we pass this as an additional template parameter: allow_spikes
+// If allow_spikes is set to true, spikes are allowed, false otherwise.
+// By default, spikes are disallowed
+//
+// Reference: OGC 06-103r4 (6.1.6.1)
+template <typename Linestring, bool AllowSpikes>
+struct is_valid<Linestring, linestring_tag, AllowSpikes>
+    : detail::is_valid::is_valid_linestring<Linestring, AllowSpikes>
+{};
+
+
+// A MultiLinestring is a MultiCurve
+// A MultiCurve is simple if all of its elements are simple and the
+// only intersections between any two elements occur at Points that
+// are on the boundaries of both elements.
+//
+// Reference: OGC 06-103r4 (6.1.8.1; Fig. 9)
+template <typename MultiLinestring, bool AllowSpikes>
+struct is_valid<MultiLinestring, multi_linestring_tag, AllowSpikes>
+{
+    static inline bool apply(MultiLinestring const& multilinestring)
+    {
+        return detail::check_iterator_range
+            <
+                detail::is_valid::is_valid_linestring
+                    <
+                        typename boost::range_value<MultiLinestring>::type,
+                        AllowSpikes
+                    >,
+                false // do not allow empty multilinestring
+            >::apply(boost::begin(multilinestring),
+                     boost::end(multilinestring));
+    }
+};
+
+
+} // namespace dispatch
+#endif // DOXYGEN_NO_DISPATCH
+
+
+}} // namespace boost::geometry
+
+
+#endif // BOOST_GEOMETRY_ALGORITHMS_DETAIL_IS_VALID_LINEAR_HPP