No
GNU GPL v3.0 or later is strong copyleft; combining it into a GNU Lesser GPL v2.1 project would force the combined work to be GNU GPL v3.0 or later (not GNU Lesser GPL v2.1). If your project must remain GNU Lesser GPL v2.1, avoid GNU GPL v3.0 or later code.
| License | Family | Patent grant |
|---|---|---|
| GNU GPL v3.0 or later (GPL-3.0-or-later) | strong-copyleft | Yes |
| GNU Lesser GPL v2.1 (LGPL-2.1) | weak-copyleft | No (implicit at most) |
GNU GPL v3.0 or later: GPL-3.0 with explicit upgrade path; users may pick GPL-3.0 or any later GPL.
GNU Lesser GPL v2.1: Library copyleft: dynamic linking permitted from non-LGPL code without triggering full copyleft.
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