With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Android's source code is closed source.
text_B: Android is a mobile operating system developed by Google , based on the Linux kernel and designed primarily for touchscreen mobile devices such as smartphones and tablets .. Google. Google. Linux kernel. Linux kernel. mobile operating system. mobile operating system. touchscreen. touchscreen. tablets. tablet computer. Android 's user interface is mainly based on direct manipulation , using touch gestures that loosely correspond to real-world actions , such as swiping , tapping and pinching , to manipulate on-screen objects , along with a virtual keyboard for text input .. user interface. user interface. direct manipulation. Direct manipulation interface. virtual keyboard. virtual keyboard. In addition to touchscreen devices , Google has further developed Android TV for televisions , Android Auto for cars , and Android Wear for wrist watches , each with a specialized user interface .. Google. Google. Android TV. Android TV. Android Auto. Android Auto. Android Wear. Android Wear. touchscreen. touchscreen. user interface. user interface. Variants of Android are also used on notebooks , game consoles , digital cameras , and other electronics .. notebooks. Laptop. game consoles. Video game console. Initially developed by Android Inc. , which Google bought in 2005 , Android was unveiled in 2007 , along with the founding of the Open Handset Alliancea consortium of hardware , software , and telecommunication companies devoted to advancing open standards for mobile devices .. Google. Google. hardware. computer hardware. software. software. Beginning with the first commercial Android device in September 2008 , the operating system has gone through multiple major releases , with the current version being 7.0 `` Nougat '' , released in August 2016 .. first commercial Android device. HTC Dream. Android applications -LRB- `` apps '' -RRB- can be downloaded from the Google Play store , which features over 2.7 million apps as of February 2017 .. Google. Google. Google Play. Google Play. apps. Mobile app. Android has been the best-selling OS on tablets since 2013 , and runs on the vast majority of smartphones .. tablets. tablet computer. , Android has two billion monthly active users , and it has the largest installed base of any operating system .. installed base. installed base. Android 's source code is released by Google under an open source license , although most Android devices ultimately ship with a combination of free and open source and proprietary software , including proprietary software required for accessing Google services .. Google. Google. proprietary. Proprietary software. software. software. source code. source code. open source license. open source license. free and open source. Free and open source software. Android is popular with technology companies that require a ready-made , low-cost and customizable operating system for high-tech devices .. high-tech. high-tech. Its open nature has encouraged a large community of developers and enthusiasts to use the open-source code as a foundation for community-driven projects , which deliver updates to older devices , add new features for advanced users or bring Android to devices originally shipped with other operating systems .. source code. source code. The extensive variation of hardware in Android devices causes significant delays for software upgrades , with new versions of the operating system and security patches typically taking months before reaching consumers , or sometimes not at all .. hardware. computer hardware. software. software. security patches. Patch ( computing ). The success of Android has made it a target for patent and copyright litigation as part of the so-called `` smartphone wars '' between technology companies .. smartphone. smartphone. smartphone wars. Smartphone patent wars
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