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diff --git a/resources/libraries/python/MLRsearch/global_width.py b/resources/libraries/python/MLRsearch/global_width.py
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+++ b/resources/libraries/python/MLRsearch/global_width.py
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+# Copyright (c) 2023 Cisco and/or its affiliates.
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at:
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""Module defining GlobalWidth class."""
+
+
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+from .discrete_load import DiscreteLoad
+from .discrete_width import DiscreteWidth
+
+
+@dataclass
+class GlobalWidth:
+    """Primarily used to synchronize external search steps across selectors.
+
+    The full name is global current width, but that is too long for identifiers.
+
+    While each selector tracks its "local" (per goal) width using expander,
+    it is important we do not interleave upper external search for two goals.
+    That is why all selector instances refer to a singleton instance of this.
+
+    In general, this value remains constant when main loop iterates over
+    selectors and when selector iterates over strategies.
+    After winner is measured, this width is set to winner width value
+    and for some strategies that width is expanded when external search says so.
+
+    The two methods are not really worth creating a new class,
+    but the main reason is having a name for type hints
+    that distinguish this from various other "width" and "current" values.
+    """
+
+    width: DiscreteWidth
+    """Minimum width to apply at next external search step."""
+    # TODO: Add a setter, so it is easier to add debug logging.
+
+    @staticmethod
+    def from_loads(load0: DiscreteLoad, load1: DiscreteLoad) -> GlobalWidth:
+        """Initialize the value based on two loads from initial trials.
+
+        :param load0: Lower (or equal) load from the two most recent trials.
+        :param load1: Higher (or equal) load from the two most recent trials.
+        :type load0: DiscreteLoad
+        :type load1: DiscreteLoad
+        :returns: Newly created instance with computed width.
+        :rtype: GlobalWidth
+        """
+        return GlobalWidth(load1 - load0)
+
+    def or_larger(self, width: DiscreteWidth) -> DiscreteWidth:
+        """Return width from argument or self, whichever is larger.
+
+        :param width: A selector (strategy) asks if this width is large enough.
+        :type width: DiscreteWidth
+        :returns: Argument or current width.
+        :rtype: DiscreteWidth
+        """
+        return width if width > self.width else self.width