From: Ferruccio Guidi <ferruccio.guidi@unibo.it>
Date: Thu, 30 Sep 2021 18:16:10 +0000 (+0200)
Subject: update in ground
X-Git-Tag: make_still_working~140
X-Git-Url: http://matita.cs.unibo.it/gitweb/?a=commitdiff_plain;h=8bbe582d87984526f40182c4409cbfd43108cb79;hp=8bbe582d87984526f40182c4409cbfd43108cb79;p=helm.git

update in ground

+ new notation for head and tail
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