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description=Fitch-style proof editor and checker;
author=Kevin C. Klement;
keywords=logic,proof,deduction;

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Text of the page (random words):
natural deduction proof editor and checker natural deduction proof editor and checker this is a demo of a proof checker for fitch style natural deduction systems found in many popular introductory logic textbooks the specific system used here is the one found in forall x calgary although based on forall x an introduction to formal logic the proof system in that original version differs from the one used here and in forall x calgary however the system also supports the rules used in the forall x cambridge remix create a new problem select if tfl or fol syntax tfl fol premises separate with or conclusion create problem proof sample exercise sets sample truth functional logic exercises chap 15 ex c chap 17 ex b sample first order logic exercises chap 32 ex e chap 34 ex a instructions tfl atomic sentences single uppercase letters a b x etc fol atomic sentences single uppercase letters other than a or e followed by lowercase letters a w without parentheses or identities pa fcdc a d etc for negation you may use any of the symbols for conjunction you may use any of the symbols for disjunction you may use any of the symbols v for the biconditional you may use any of the symbols or in tfl only for the conditional you may use any of the symbols for the universal quantifier fol only you may use any of the symbols x x ax ax x x for the existential quantifier fol only you may use any of the symbols x x ex ex x for a contradiction you may use any of the symbols xx the following buttons do the following things delete this line add a line below this one add a new subproof below this line add a new line below this subproof to the parent subproof add a new subproof below this subproof to the parent subproof apart from premises and assumptions each line has a cell immediately to its right for entering the justifcation click on it to enter the justification as e g i 1 2 hopefully it is otherwise more or less obvious how to use it the php javascript html and css source for this page is licensed under the gnu general purpose license gpl v3 download it here rules basic rules derived rules rules for cambridge