From a03127b6c863b09a27870d4997e1d8ffddbb5a35 Mon Sep 17 00:00:00 2001
From: Travis Scrimshaw <tcscrims@gmail.com>
Date: Tue, 19 Mar 2024 19:15:43 +0900
Subject: [PATCH] Implement a bool for posets.

---
 src/sage/combinat/posets/posets.py | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/src/sage/combinat/posets/posets.py b/src/sage/combinat/posets/posets.py
index 36f4d1eee10..6db41768e1e 100644
--- a/src/sage/combinat/posets/posets.py
+++ b/src/sage/combinat/posets/posets.py
@@ -1230,6 +1230,21 @@ def unwrap(self, element):
         else:
             return element.element
 
+    def __bool__(self) -> bool:
+        r"""
+        Return if ``self`` is empty or not.
+
+        EXAMPLES::
+
+            sage: P = Poset((divisors(15), attrcall("divides")), facade=True)
+            sage: bool(P)
+            True
+            sage: P = Poset()
+            sage: bool(P)
+            False
+        """
+        return bool(self._elements)
+
     def __contains__(self, x) -> bool:
         r"""
         Return ``True`` if ``x`` is an element of the poset.