From lojban+bncCK30vq5WENOziugEGgTI3UoC@googlegroups.com Fri Dec 10 13:21:38 2010 Received: from mail-pv0-f189.google.com ([74.125.83.189]) by chain.digitalkingdom.org with esmtp (Exim 4.72) (envelope-from ) id 1PRAPF-0007Mf-3i; Fri, 10 Dec 2010 13:21:38 -0800 Received: by pvh1 with SMTP id 1sf1331283pvh.16 for ; Fri, 10 Dec 2010 13:21:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=googlegroups.com; s=beta; h=domainkey-signature:received:x-beenthere:received:received:received :received:received-spf:received:date:from:to:subject:message-id :references:mime-version:in-reply-to:user-agent:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:sender:list-subscribe :list-unsubscribe:content-type:content-disposition; bh=bSN0QK5IDKfULSkWIjhO7d9SpnXNwb6bX9RVhGOpLaA=; b=PwV9FswP4DIUeXoRPJpqm2R0nMhAE6uwF31zdzBaKvTVNjKRrpz+mjHV8FhuS2XtSd WiRFlFKBr5Vu4IqGsg97JdObxNFyOJcD+zRAvF2G0BDZsEPh7r9W+qaGv3Yo9eKOr//c jDpJctIkyUCRG7/e0Ta3wE5LKO/azKhkqL8vs= DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlegroups.com; s=beta; h=x-beenthere:received-spf:date:from:to:subject:message-id:references :mime-version:in-reply-to:user-agent:x-original-sender :x-original-authentication-results:reply-to:precedence:mailing-list :list-id:list-post:list-help:list-archive:sender:list-subscribe :list-unsubscribe:content-type:content-disposition; b=fTHBjhwjolq9Uk0Jv5r9+5GDpBeJdItQ0R7Qhh4gH7Wf2r+3m5AMa7swaimqYSbi0x 9S/hP2gE4DPm6jjOa/t/+1ko44XhkrbgDhW7MW1WVMgyjapNweNTCOnSwPnE28vlDCbo TNpNoSbkprlBBG94nTaMe+Brx8EC404DXYvlw= Received: by 10.142.150.10 with SMTP id x10mr61507wfd.56.1292016083335; Fri, 10 Dec 2010 13:21:23 -0800 (PST) X-BeenThere: lojban@googlegroups.com Received: by 10.142.249.41 with SMTP id w41ls4548386wfh.1.p; Fri, 10 Dec 2010 13:21:22 -0800 (PST) Received: by 10.142.169.14 with SMTP id r14mr849756wfe.51.1292016082501; Fri, 10 Dec 2010 13:21:22 -0800 (PST) Received: by 10.142.169.14 with SMTP id r14mr849755wfe.51.1292016082476; Fri, 10 Dec 2010 13:21:22 -0800 (PST) Received: from chain.digitalkingdom.org (digitalkingdom.org [173.13.139.234]) by gmr-mx.google.com with ESMTP id y8si3875802wfj.1.2010.12.10.13.21.22; Fri, 10 Dec 2010 13:21:22 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of rlpowell@digitalkingdom.org designates 173.13.139.234 as permitted sender) client-ip=173.13.139.234; Received: from rlpowell by chain.digitalkingdom.org with local (Exim 4.72) (envelope-from ) id 1PRAP3-0007MZ-8O for lojban@googlegroups.com; Fri, 10 Dec 2010 13:21:21 -0800 Date: Fri, 10 Dec 2010 13:21:21 -0800 From: Robin Lee Powell To: lojban@googlegroups.com Subject: Re: [lojban] Lojban CFG Questions Message-ID: <20101210212120.GG27025@digitalkingdom.org> References: <201012101024.39320.roman_naumann@fastmail.fm> MIME-Version: 1.0 In-Reply-To: <201012101024.39320.roman_naumann@fastmail.fm> User-Agent: Mutt/1.5.20 (2009-06-14) X-Original-Sender: rlpowell@digitalkingdom.org X-Original-Authentication-Results: gmr-mx.google.com; spf=pass (google.com: best guess record for domain of rlpowell@digitalkingdom.org designates 173.13.139.234 as permitted sender) smtp.mail=rlpowell@digitalkingdom.org Reply-To: lojban@googlegroups.com Precedence: list Mailing-list: list lojban@googlegroups.com; contact lojban+owners@googlegroups.com List-ID: List-Post: , List-Help: , List-Archive: Sender: lojban@googlegroups.com List-Subscribe: , List-Unsubscribe: , Content-Type: text/plain; charset=ISO-8859-1 Content-Disposition: inline On Fri, Dec 10, 2010 at 10:24:39AM +0100, Roman Naumann wrote: > Hello dear lojbanistanians, > > i'm starting with an attempt to find a CFG for lojban - or if it > shows impossible, to prove it being impossible (so that you see > what exactly is impossible and thus to improve). > > Back in 2008 when there was a challenge [1] to do exactly that, i > would have done it, but i lacked the knowledge to proof or > proof-wrong grammars. Learned it during the last year at > university and thought, hey, why not put it to use. FWIW, formal proof is not required for the "yes we can" case; an example grammar that clearly parses the language decently well will do fine. > However, i realized just now looking at the EBFN [2] causes eye cancer. Hahahah. > Also, i've never been good with lojban at all. I don't get the > (formalizing) problem with elidable terminators yet. To get > started, it would be extremely helpful to work on an abstraction. > I'd be glad if you could provide such to me. Here's a very very simplified Lojban for you. It has exactly 4 words: lenu, mi, klama, ku (note to oldbies: yes, I treated lenu as one word; yes, those of you who know me know I hate compound cmavo; it's a special case, go stick your head in a pig) A sentence is zero or more sumti, followed by klama, followed by zero or more sumti. A sumti is either "mi" or "lenu" followed by a sentence. "ku" ends a "lenu" sentence immediately. From what we have so far, you'd expect: lenu mi klama mi klama mi to fail to parse, but in fact it parses just fine: because a sentence can have only one "klama", upon seeing a second one the parser goes "Oh, they forgot to put a "ku" in, but there needs to be one for the parse to work, so I'll just insert it". So what the parser sees is actually: lenu mi klama mi ku klama mi (note: not actually true in real Lojban) Which, loosely, parses like so: sentence=( sumti=(lenu sentence=(mi klama mi) ku) klama mi) That, in a nutshell, is the elidable terminator problem: making terminators act as though they were included when they actually weren't, but the sentence parses if they were (and doesn't if they weren't). You have to solve it *without* significantly changing the definition of "sentence" I gave you. Solving this toy version won't prove much about the full version, but it's a good start. -Robin -- http://singinst.org/ : Our last, best hope for a fantastic future. Lojban (http://www.lojban.org/): The language in which "this parrot is dead" is "ti poi spitaki cu morsi", but "this sentence is false" is "na nei". My personal page: http://www.digitalkingdom.org/rlp/ -- You received this message because you are subscribed to the Google Groups "lojban" group. To post to this group, send email to lojban@googlegroups.com. To unsubscribe from this group, send email to lojban+unsubscribe@googlegroups.com. For more options, visit this group at http://groups.google.com/group/lojban?hl=en.