Question: What larger group of mountains includes the mountain range that Grassen is a part of?

full_context: Document 1: Grassengrat: The Grassengrat is a multi-summited mountain of the Urner Alps, located on the border between the cantons of Obwalden and Uri in Central Switzerland. It lies on the range between the Titlis and the Gross Spannort. The main summit has an elevation of 2,941 metres and is named "Stössenstock".
Document 2: Alps: The highest portion of the range is divided by the glacial trough of the Rhone valley, with the Pennine Alps from Mont Blanc to the Matterhorn and Monte Rosa on the southern side, and the Bernese Alps on the northern. The peaks in the easterly portion of the range, in Austria and Slovenia, are smaller than those in the central and western portions.
Document 3: Gross Furkahorn: The Gross Furkahorn is a mountain of the Urner Alps, located on the border between the Swiss cantons of Valais and Uri. It lies north of the Furka Pass and east of the Rhone Glacier.
Document 4: Alps: The Alps (/ælps/; Italian: Alpi [ˈalpi]; French: Alpes [alp]; German: Alpen [ˈʔalpm̩]; Slovene: Alpe [ˈáːlpɛ]) are the highest and most extensive mountain range system that lies entirely in Europe, stretching approximately 1,200 kilometres (750 mi) across eight Alpine countries: Austria, France, Germany, Italy, Liechtenstein, Monaco, Slovenia, and Switzerland. The Caucasus Mountains are higher, and the Urals longer, but both lie partly in Asia. The mountains were formed over tens of millions of years as the African and Eurasian tectonic plates collided. Extreme shortening caused by the event resulted in marine sedimentary rocks rising by thrusting and folding into high mountain peaks such as Mont Blanc and the Matterhorn. Mont Blanc spans the French–Italian border, and at 4,810 m (15,781 ft) is the highest mountain in the Alps. The Alpine region area contains about a hundred peaks higher than 4,000 m (13,123 ft), known as the "four-thousanders".
Document 5: Gärstenhörner: The Gärstenhörner is a mountain in the Urner Alps, located on the border between the Swiss cantons of Bern and Valais. It lies on the range west of the Rhone Glacier, and east of the Grimsel Pass. The Gärstenhörner has three summits: the Mittler Gärstenhorn (3,189 m), the Hinter Gärstenhorn (3,173 m) and the Vorder Gärstenhorn (3,167 m).
Document 6: Ruchstock: The Ruchstock is a mountain of the Urner Alps in Central Switzerland. Near its summit is located the tripoint between the cantons of Nidwalden, Uri and Obwalden. The summit itself (2,814 metres) is on the border between Nidwalden and Uri.
Document 7: Säntis: At 2,501.9 metres above sea level, Säntis is the highest mountain in the Alpstein massif of northeastern Switzerland. It is also the culminating point of the whole Appenzell Alps, between Lake Walen and Lake Constance. Shared by three cantons, the mountain is a highly visible landmark thanks to its exposed northerly position within the Alpstein massif. As a consequence, houses called "Säntisblick" (English: "Säntis view") can be found in regions as far away as the Black Forest in Germany. Säntis is among the most prominent summits in the Alps and the most prominent summit in Europe with an observation deck on the top. The panorama from the summit is spectacular. Six countries can be seen if the weather allows: Switzerland, Germany, Austria, Liechtenstein, France, and Italy.
Document 8: Galenstock: The Galenstock (3,586 m) is the fourth highest mountain in the Urner Alps in Switzerland. Its summit ridge lies on the border between the cantons of Uri and the Valais.
Document 9: Seetalhorn: The Seetalhorn is a mountain of the Swiss Pennine Alps, overlooking Grächen in the canton of Valais. With an elevation of 3,037 m, it is the highest point of the ski area of Grächen.
Document 10: Graustock: The Graustock is a mountain of the Urner Alps, located south of Engelberg in Central Switzerland. The summit is one of the two tripoints between the cantons of Berne, Nidwalden and Obwalden (the other being the Jochstock).
Document 11: Brisen: The Brisen is a mountain of the Urner Alps, located on the border between the cantons of Nidwalden and Uri, in Central Switzerland. It is located near the slightly higher Hoh Brisen.
Document 12: Uri Alps: The Uri Alps (also known as "Urner Alps", ) are a mountain range in Central Switzerland and part of the Western Alps. They extend into the cantons of Obwalden, Valais, Bern, Uri and Nidwalden and are bordered by the Bernese Alps (Grimsel Pass) and the Emmental Alps to the west (the four lakes: Lungerersee, Sarnersee, Wichelsee, and Alpnachersee), the Schwyzer Alps to the north (Lake Lucerne), the Lepontine Alps to the south (the valley of Urseren with Andermatt) and the Glarus Alps to the east (Reuss).
Document 13: Schwalmis: The Schwalmis is a mountain of the Urner Alps, overlooking Lake Lucerne in Central Switzerland. Its summit lies on the border between the cantons of Nidwalden and Uri.
Document 14: Switzerland: Switzerland lies between latitudes 45° and 48° N, and longitudes 5° and 11° E. It contains three basic topographical areas: the Swiss Alps to the south, the Swiss Plateau or Central Plateau, and the Jura mountains on the west. The Alps are a high mountain range running across the central-south of the country, comprising about 60% of the country's total area. The majority of the Swiss population live in the Swiss Plateau. Among the high valleys of the Swiss Alps many glaciers are found, totalling an area of 1,063 square kilometres (410 sq mi). From these originate the headwaters of several major rivers, such as the Rhine, Inn, Ticino and Rhône, which flow in the four cardinal directions into the whole of Europe. The hydrographic network includes several of the largest bodies of freshwater in Central and Western Europe, among which are included Lake Geneva (also called le Lac Léman in French), Lake Constance (known as Bodensee in German) and Lake Maggiore. Switzerland has more than 1500 lakes, and contains 6% of Europe's stock of fresh water. Lakes and glaciers cover about 6% of the national territory. The largest lake is Lake Geneva, in western Switzerland shared with France. The Rhône is both the main source and outflow of Lake Geneva. Lake Constance is the second largest Swiss lake and, like the Lake Geneva, an intermediate step by the Rhine at the border to Austria and Germany. While the Rhône flows into the Mediterranean Sea at the French Camarque region and the Rhine flows into the North Sea at Rotterdam in the Netherlands, about 1000 km apart, both springs are only about 22 km apart from each other in the Swiss Alps.
Document 15: Grassen: The Grassen is a mountain of the Urner Alps, located east of the Titlis in Central Switzerland. The summit is the tripoint between the cantons of Berne, Obwalden and Uri.
ground_truth: Western Alps
sub_queries: Grassen >> part of Answer: Urner Alps
Urner Alps >> part of Answer: Western Alps