Path: ...!news.roellig-ltd.de!open-news-network.org!weretis.net!feeder8.news.weretis.net!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Moebius Newsgroups: sci.math Subject: Re: How many different unit fractions are lessorequal than all unit fractions? Date: Sat, 5 Oct 2024 21:02:45 +0200 Organization: A noiseless patient Spider Lines: 20 Message-ID: References: <8c94a117d7ddaba3e7858116dc5bc7c66a46c405@i2pn2.org> <8ce3fac3a0c92d85c72fec966d424548baebe5af@i2pn2.org> <55cbb075e2f793e3c52f55af73c82c61d2ce8d44@i2pn2.org> Reply-To: invalid@example.invalid MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Injection-Date: Sat, 05 Oct 2024 21:02:45 +0200 (CEST) Injection-Info: dont-email.me; posting-host="a68c63666759ee15cd78797800189e4d"; logging-data="920583"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+jMxUJe6xzPH+gGzhATwKv" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:PGlrnaQjiSLHNymQfh9M/pZoeq4= Content-Language: de-DE In-Reply-To: Bytes: 2480 Am 05.10.2024 um 19:18 schrieb Moebius: > Am 05.10.2024 um 16:58 schrieb Moebius: >> Am 05.10.2024 um 15:57 schrieb Alan Mackenzie: >> >>> I first came across the terms "potential infinity" and "actual infinity" >>> on this newsgroup, not in my degree course a few decades ago.  I'm not >>> convinced there is any mathematically valid distinction between them. >> >> Actually, there is. > > "Nearly all research-level mathematicians today (I would guess 99.99% of > them) take for granted both "potential" and "completed"  [aka "actual"] > infinity, and most probably do not even know the distinction indicated > by those two terms." > > Source: https://math.vanderbilt.edu/schectex/courses/thereals/potential.html Also quite interesting: https://math.vanderbilt.edu/schectex/papers/difficult.html