Assertion: lepton | /r/HasProperty | observed
Facets:
Source sentences:
text: The next lepton to be observed was the muon, discovered by Carl D. Anderson in 1936, which was classified as a meson at the time.
text: The next lepton to be observed was the muon, discovered by Carl D. Anderson in 1936, but it was erroneously classified as a meson at the time.