ELEMENT S OF METAMATHEMATICA L AN D INFORMATIONA L CALCULUS Anton P. Zeleznikar An Active Member of the New York Academy of Sciences Volaričeva ulica 8, SI 61111 Ljubljana, Slovenia Keywords: axioms of parallelism, serialism, circularity and spontaneity; catalogue of informatio­nal rules; decomposition axioms, decomposition theorem, deduction theorems, implicative axioms, inference rules; informational calculus, predicate calculus, propositional calculus; substitution rule; various axioms and theorems (implicative, conjunctive, disjunctive, equivalent, negatory, etc.) Edited by: L. Birnbaum Received: November 4, 1994 Revised: January 11, 1995 Accepted: February 3, 1995 This article deais with problems pertaining to the elements ofa.xioma.tics in traditional (mathematical, symbolic, philosophical) logic and to the problems ofnewly emerging axi­omatics in informational logic. Informational axioms can be derived from propositional and predicate axioms and then, particularized and universalized within the informatio­nal domain. Traditional axiomatic formulas of the propositional and predicate calculus can become a rebounding cause for the construction of essentially different axioms in general informational theory. It is shown how propositional and predicate axioms and rules can be informationally extended for the needs of the general informational theory. 1 Introductio n Which are the basic and inferential informational ajdoms1 which govern the derivation of formu­las (theorems, consequences), that is, their pro­ving procedures (proofs) in informational theo­ries? This question is signiflcant for the consci­ousness of tha t what scientific theories do out­side of theories themselves, in their—from theo­ries themselves separated—metatheories. On the other hand, informational theories are always uni­ons of object theories and metatheories, where the last have the role of being the producers of theo­ries in the sense of informational arising, that is, spontaneity and circularity. 2 Fundamenta l Figures of Syllogistic Inference Syllogistic inference can be interpreted in different ways, for instance, in the scholastic (philosophi­ •"This paper is a private author's work and no part of it may be used, reproduced or translated in any manner whatsoever vvithout vvritten permission except in the čase of brief quotations embodied in critičal articles. cal), informational and traditional-mathematical manner. 2.1 An Informational Interpretation of Syllogism Syllogism (av\\ojrj, in Greek, means ga­thering, collecting, assembly, concourse and av\\o'yi(ofica means to reckon, consider, think, reilect; to infer, conclude) (in German, das Zu­sammenrechnen, der Schlufj, die Folgerung) is a valid (e.g., true) inference in a syllogistic form. Syllogistics (in Greek, avXXojiaTiKfj Tixvf) the art of inferring, concluding) was founded by Aristotle and developed in scholasticism as tea­chings of (correct) inference in syllogistic form. This technique became the keystone of the tradi­tional logic ([4], pp. 407-409). The inferring in a svllogistic form proceeds from two premises to one conclusion. Thus, the valid inference, the so-called syllogism, with true pre­mises, delivers a true conclusion. In parallel to the traditional logic, as premises of syllogisms, only the following forms of 'equivalent' informational formulas are allowed: 1. "Ali x are F(x)? Formula x \=VxF(x) is a universal afnrmative judgement and re­ads, informationally, x informs for ali x the property (entity) F(x). 2. "No x is F(x)." Formula x \L\/xF(x) is a universal negatory judgement and reads, informationally, x does not inform for ali x the property (entity) F(x). 3. "Some x are F(x)" Formula x \=3x F(x) is a partial afnrmative judgement and reads, informationally, x informs for some x the pro­perty F(x). 4. "Some x are not F(x)" Formula x \Č3X F(x) is a partial negatory judgement and reads, informationally, x does not inform for some x the property (entity) F(x). The connections among these four formulas can be presented by the logical quadrate in Fig. 1. contrary X \=Vx F(x) X ^v * F(x) sub- sub- al- al­ ter­ ter­ nate nate CD X \=3x F(x) X \Č3x F(x) contrary Figure 1: The logical quadrate, dramn according to the informational formulas of svllogistics. CD means contradictory. Four fundamental figures of the syllogistic in­ference can be distinguished, where |=„, |=f, and |=c are determined by A.P. Zeleznikar l=ci,N,|=c L {\=Vx,\Lvx,\=3x,\/:3x} The position of the so-called middle entity [i is decisive and it must appear in both premises in the following manner: (FF1) (FF2) a\=cir <7(=C7T (FF3) (FF4) a |=C TT a |=c 7T If operators |=a, |=f, and |=c are replaced through concrete (particularized) operators |=va;, ^v ^ 1=32; and \^3X, for every čase an inference modus is obtained. In ali, there are 43 = 64 modi for each fundamental inference figure, that is, 256 figures. Only 24 of them are valid, that is, syllogisms (6 for each fundamental form, and for some additio­nal suppositions have to be introduced). A modus is uniquely determined if the fundamental figure and the operators |=0, f=b and |=c are known. 2.2 A Mathematical Interpretation of Syllogism In modern logic, syllogism is treated in the fra­mework of the first order predicate logic. The so-called universal and existential qauntifier, V and 3, can be represented with conjunctive (A) and disjunctive (V) logical connectives within a cer­tain domain (set) D of elements. E.g., the schola­stic modi "Barbara" and "Felapton", where the emphasized a stands "for ali", e for "no", and o for "some . . .are not", become •+ P ( x ) \ xeD A s(x) -* M(x) \xeD J and A s(x) --> P(x) ( A M(z)--P{*) \ xLD -, S(x) A M(x) • \xeD J V S{x)i\ P(x) x€D respectively. The premise f\ M(x) in Felapton must be completed. Predicate P(x) corresponds to the middle entity /d in fundamental formulas (FF1-4) and, adequately, predicates P(x) and S(x) correspond to entities 7r and a in (FF1-4). The reader can find the logic quadrate for for­mulas, together with negatory cases, using univer­sal and existential quantifiers and predicate F{x) in Fig. 2, contrary VxF(x) 3xF(x) sub- sub- al- al­ ter­ ter­ nate nate CD 3xF(x) VxF(x) contrary Figure 2: The logical quadrate, drawn according to the predicate formulas of syllogistics using quan­tifiersV and 3. CD means contradictorv. In Fig. 2 the contrary, contradictory and subaL ternate cases are shown in a clear, that is, nega­tory manner. There is, certainly, sixF{x) = 3xF(x) and 3xF{x) = MxF{x) and this equivalences (see Subsection 3.7) can be used as interpretations in Fig. 3. A Short Overview of Some Mathematica l Axioms In der Aussage: „Der Hammer ist zu schwer" ist das fiir die Sicht Entdeckte kein „Sinn", sondern ein Seiendes in der Weise seiner Zuhandenheit. ...Aussage besagt soviel wie Prddikation. Von .einem „Subjekt" wird ein „Pradikat" „ausgesagt", jenes wird durch dieses be­stimmt. Das Ausgesagte in dieser Be­deutung von Aussage ist nicht etwa das Pradikat, sondern „der Hammer selbst". Martin Heidegger [2] 154 Informatica 19 (1995) 345-370 347 contrary \fxF(x) yXF{x) sub- sub­ al- al­ ter- ter­ nate nate CD 3xF(x) 3xF(x) contrary Figure 3: The logical guadrate, drawn according to formulas in the previous picture with the resolved negations of the guantified formulas. CD means contradictorv. 3.1 Introduction What is the nature of mathematical axioms and which kind of axioms are significant for our di­scussion? As we shall see, propositional axioms can serve as an outlook to the axioms used in the predicate calculus and also in the informational approach. The beginning of the general informa­tional theory (GIT) has to be founded in logical axioms by which the informational phenomena­lism (externalism, internalism, metaphysicalism) becomes a consequence of the very first assump­tion, that is, of the informational entity. 3.2 Axiom s of th e Propositiona l Calculus Aussage bedeiitet primar Aufzeigung. ... Aussage bedeutet Mitteilung, Hera­ussage. Als diese hat sie direkten Bezug zur Aussage in der ersten und zweiten Beduetung. Sie ist Mitsehenlassen des in der Weise des Bestimmens Aufgezeig­ten. Martin Heidegger [2] 154-155 Axioms of propositional calculus are fundamen­tal for (the entire) mathematics (metamathema­tics) so that they can be reasonably extended, for example, to different predicate calculuses, ari­thmetic and mathematical logic in general. There are sever al "systems of axioms" which differ, thro­ugh tirne, from one author to another. In our approach, the axiomatic systems of Hilbert [3] and Novikov [5] were chosen. In propositional calculus, axioms can be grou­ped in a traditional way (e.g., following Hilbert and Bernays [3] and Novikov [5]). According to [3], p.66, the initial axiomatic formulas can be grouped and, roughlv, written in the form of axi­omatic rules: I. Axioms of implication 1) A-(B->A) , 2) (A - (A -B)) -> (A -B), 3) (A-JB)-(OB->C)-(A-C D II. Axioms of conjunction i) AAB^A, 2) AAB^B, 3) (A-+B)^> ((A^C)^(A^BA C)) III. Axioms of disjunction 1) A-*4V5 , 2) 5-4AV5 , 3) (A^C)^ ((B -> C) -• (A V B -• C)) IV. Axioms of equivalence 1) (A = 5 ) - (A - 5) , 2) (A = 5)-(5-A) , 3) (A-5)-((B-A)-( A = 5)) V. Axioms of negation 1) (A -+_0) -+ (B -»• A) , 2) A^Z , 3) A-* A The presented system of propositional axioms is not the only possible. For instance, Novikov [5], p. 75, chooses the group I of implication axioms in the form 1) A ^( B ^ A), 2 ) (A - (A-> C»-> «A - 2?) - (A - C]) Various axioms can be useful for the interpreta­tion of basic informational cases of phenomena­lism, as we shall see in one of following subsecti­ons. 3.3 Inference Rules of the Propositional Calculus Inference rules of propositional calculus are con­structed on the basis of propositional axioms in the preceding subsection. It is hard to say which A. P. Zeleznikar "rules" are the primarv, the axiomatic or the in­ferential. However, it is clear that inferential ru­les must strictly consider the primitive axioms of propositional calculus which are, for example, im­plicative, conjuctive, disjunctive, equivalent and negatory. Which is the general philosophy of making (constructing) arule, precisely, the inference rule? Irrespective of the theory, for which rules are con­structed, these are always implicative, although they express something more than a pure impli­cation, because they concern the so-called deriva­tion procedure. The role of a rule in the deriva­tion procedure is the folknving: taking a rule in which several premises are logically connected in one or another way, some of them can be deta­ched in the form of the so-called conclusion and, thus, between the respective premises of the rule and its conclusion a special operator, marked by h is used in propositional and predicate calculus while in the informational calculus we use opera­tor -» for marking derivation and an operator (­for marking the circular form of informing. Let us settle the general form of an inferential rule for deriving propositional formulas from axi­oms or from already deri ved formulas. The iirst rule is substitution. Let us mark propositional formulas which depend on various propositional variables by the capital Fraktur letters, for example, as 21 or, in more detail, 2l(Ai, A2, • • •, An). Let S mark the operator of substitution (in informational terms, the function of substitution). Let us introduce s;i 1^^Ba(Ai,A2,...>AB) = ^(•••Sj2 2(s51 12l(Al!A2,...,An))...) where Q5i, ©2, • • •, 2J„ are propositional (identi­cally true) formulas. Thus, the substitution rule has the form gi(A1,A2,---,Ara) s;i 1 l^.;xfBa(Ai,A2,...,An) The second production rule is applied to a formula which is structured as a parenthesized sequence of implications, that is, 2ii-*(si2->(---(a„-i-»»«)•••) ) and is expressed in the following manner: if for­mulas 2li, 2l2, • • •, 2ln_i and ai->(a2 -.(---(2in _i-*sin )---) ) are true then formula 2l„ is true in the propo­sitional calculus. The complex rule of inference (modus ponens) is 2li,5l2,---,Sln-i , In general, we have the following scheme of infe­rence, where ^3; are true premises and • • -, Qn H Ci, € 2, ••-,€ « 3.4 A Theore m of Deductio n withi n th e Propositiona l Calculu s Formula 93 is derivable from formulas 2ti, 2l2> • • •» 2ln, that is, Sli, 2l2, • • •, »n I" » if it is possible to derive formula 35 merely by means of inference rules, using the initial formulas 2lii 2I2, • • •. 2l„ and any true formulas within the propositional calculus. Informatica 19 (1995) 345-370 349 Deduction Theorem. If formula !B is derivable from formulas 2li, 2I2, • • •> 2l„, i/zen 2li-(5l 2-(--•(«„-»)•••)) is a true formula. • By induction it is possible to prove the following: if 2l1,2l2,"-,2lIl_1,2ln h » then Sli, 2t2, • • •, 2ln_! h 2l„ - \fx 21(.T) is a true formula too. 2. If 2l(a?) —»• *B is a true formula and 93 does not include variable x, then 3x 2l(a;) —> 2$ is a true formula too. The basic inference scheme (rule of modus po­nens) of the predicate calculus remains 21 21-+ » B(o) 21-» »(b ) 2X -*• «B(t) 2i^!B(a) A »(b)A---A»(e ) Another inference scheme, with the universal quantifier, being important for a later considera­tion could be 21 -> «8(o) 21 -*• Va; »(s ) where x must not appear in *B(a). The next infe­rence scheme which comes out is, for instance, 21 -• (® -+ H) 21 -»• ( S ->• 2J) 21 -•• ( » -»• i l A 93) This scheme can be extended by a transition from a two-part conjunction to the value domain of a variable a, that is, 21 -> (<8 -»• €(a)) »-*(»-» Va; (L(»)) where in the premise a; must not appear. Analogously, for the existential quantifier, the scheme 3xF{x), Vx\/yF(x,y) = Vy\/xF(x1y), 3xVyF(x,y) -* Vy3xF(x,y), H Vx(F(x) -»• G(x)) -> (\/xF(x) -• VsG(a:)), 1- Vz^Oc ) -• G(s)) -> {3xF(x) -f 3a:G(a:)), h Var(f(a) = G(z)) -»• (Va:F(a:) = Va?G(a:)), 3xF(x) = VxF(x), 3xF(x) = VxF(x), 3xF(x) = VxF(x), 3xF(x) = VxF(x) ivhere 21 = 23 represents the formula (21 -> 23) A (25 -• 21) D Proofs for the listed theorems can be found in [5]. 4 Axioms within an Informational Theory 4.1 Introduction The question is how could the axioms of the pro­positional and predicate calculus be turned over to informational calculus. The main difference se­ems to be between the realm of truth in the tradi­tional logic and realm of information in the infor­mational logic. The informational realm is sub­stantially broader and within it the truth appe­ars only as a very particular čase. Instead to say that formulas in the traditional logic are true or false, in the informational logic formulas can in­form in one or another way, truly and falsely, par­ticular^ and universally, in parallel and serially, straightforwardly and circularly, algorithmically and spontaneously, programmingly and intelligen­tly, routinely and creatively, logically (consisten­tly) and controversially, etc. Informational logic becomes an active part of any informational sy­stem, the theoretical and the practical one. Informatica 19 (1995) 345-370 351 4.2 Axioms of the Informational Calculus Axioms of informational calculus can find a logi­cal support in axioms of propositional and pre­dicate calculus (Subsections 3.2 and 3.5, respec­tively). At the first glance, the axiom designer can behave in a withholding way, considering the traditional axioms as much as possible. But, the­reupon, when getting the appropriate experience, the designer of an informational theory can go his/her own way, considering the entirety of the possible informational realm. Within this gene­ral scope, the true as a particular situation can be replaced by the informational as an extreme attitude of the informationally possible. The di­scussion in this section will follow the traditional way of axiom construction as much as possible. In the next section the most general and infor­mationally open way will replace the traditional thinking. First, let us classify the informational axioms according to the tradition in the propositional and predicate calculus. This way of interpretation will give us the necessary feeling of difference and in­formational generality in respect to the usual un­derstanding of "logical" axioms. It will be possi­ble to recognize the essential difference which go­verns the informational realm in its universality in comparison to the classical logical (propositional, predicate) realm. It certainly does not mean that the particular axiom. situation in logical calculu­ses does not nt the informational principles—it fits them in a particular manner. 4.2.1 "Implication" Axioms of the Informational Calculus In čase of implicational axioms, we are concer­ned with two basic possibilities. At the begin­ning of the axiomatizing process we are concer­ned with the so-called informational phenomena­hsm for which we have to design particular axi­oms giving us the certainty of our initial steps into a general theory of the informational. This means, we have to explain in a formally consi­stent way the arising of initial axioms themselves. For instance, we must induce the primitive axioms of externalism, internalism and metaphysicalism, which constitute the very general axiom of infor­mational phenomenahsm. In Subsection 3.2 we listed the group of axioms of implication. In informational calculus, we have a broader definition of the so-called informatio­nal implication, discussed in [10]. The question is where to begin the process of axiomatization in in­formational calculus. We are confronted with the principal difference existing between the truth in logical calculuses and the informing in informati­onal calculus. In the traditional logic, propositions and predi­cates inform in a true or false manner. In the informational calculus, informational entities— precisely informational operands—inform and are informed. Thus, we can choose the operand— informational entity—as the point from which one can begin the process of axiomatization. We shall see how different initial axioms will become pos­sible and how they will be circularly interwea­ved. This axiomatic analysis will deepen the un­derstanding of the informational phenomenalism, that is, the phenomenalism of the informational entity. According to Subsection 3.2, axioms I. 1-3, in informational čase, the following is obtained: I. Axioms of informational implication 1) a => (/3 =>• a), 2) (a=^(a=> P)) =} • ( a = » P), 3) (a = > p) => ((/? = * 7 ) = • (a 7)) where a and /3 are informational operands (enti­ties) and =>• represents the operator of informati­onal implication (in the most general and complex form [10]). Prior to the informational systemization of im­plication axioms, let us look at examples which bring to the surface the logical sense of the li­sted implication axioms within the informational realm. An axiom of the form (1.1) a = > ((a |=) = > a) (1) seems to be regular. It means that an informatio­nal entity a simply implies that entity a is implied by informing of the entity, tha t is, by a \=. Theo­retically, it seems to be impossible to oppose such an initial principle because the informational na­ture of an entity is circular in respect to itself and its informing. If introducing a' s informing in the A.P. Zeleznikar form 3a, the last axiom can be expressed in the form (Jo, = > a) (2) a This form of the axiom is more general then the preceding one since it presupposes also the phe­nomenon of informational internalism, tha t is, a =*• ((|= a) =>• a) (3) However, there is not an equivalence betvveen the first (1) and the third (3) axiom on one side and the second (2) axiom on the other side. A resulting system of axioms concerning infor­mational phenomenalism in the sense of the pro­positional axiom (1.1) in Subsection 3.2 is a =>•(/? =*• a) ; P € {« K [=a > a \= «i (a N; N ")} or informationally explicitly (I a=* pe a \ \ or simply and evidently a =*-a I In this formula, the essential difference between "informational operators" comma and semicolon must be distinguished (the alternative and the pa­rallel operator, respectively). An extension of the discussed axiom system is evidently the following: An example of this system is not only the axiom (a h ) = > ((h «) = > (« H) which fits the general axiomatic scheme (1.1), but also ( a |=) = > ((|= a) =$• (a \= a)) if arbitrary items of alternative array (a , a (=, |= a, a (= a, ( a |=; |= a)) are chosen. It is to stress tha t cases of non-informing, that is, a h L^ a, a\L a, etc. are understood as particular cases of informing. Informational axiom (1.2) offers other signifi­cant formulas (basic informational implications) which are used, for instance, in informational mo­dus ponens and modus tollens. One of the most important informational axi­oms, following the scheme (1.2), seems to be (a=*(a=> (a |=))) = • (a = > (a [=)) which delivers the necessary conclusion a =>• (a |=) needed in various rules of inference. A resulting system of axioms concerning infor­mational phenomenalism in the sense of the pro­positional axiom (1.2) in Subsection 3.2 is (a => (a => /?)) ==> ( a = > /?); P G { a |=, |= a , a |= a , ( a |=; |= a) } or informationally explicitly / / / \\\ h«, a => a =>• /?€ < a |= a, • V l l HMJ J l a / M V v One can imagine what happens if the first /? and the second /3 in the last formula are chosen as di­fferent entities which, in the last scheme, is possi­ble in several ways. Appearances of /3 within the alternative scheme (set) are legal independently of the randomly chosen element in each concrete čase. It is to mention that some alternative infor­mational schemes concerning the axiomatic atti­tude will also be discussed in Subsection 4.2.2. This particular axiomatic situation can now be transformed simply and evidently into a more ge­neral axiomatic scheme of the form Informatica 19 (1995) 345-370 35 3 a a \ \ l /ah W |=a , a => a\= a, \ \\=<*JJJ The most general extension of the discussed axiom system could evidently be the follovving: A characteristic and progressively diverse form of the last axiom system would be, for example, ( a = • ((a |=) =* (1= «))) = » ((a |= a ) = > ( a h ; N a)) which shows a phenomenalistic sequence exten­ding in a straight implicative manner from infor­mational entity a over its externalism a |= and internalism \= a to its metaphysicalism a (= a and phenomenalism a |=; |= a. Axiomatic scheme (1.3) delivers a very funda­mental property of informing of two entities con­cerning the third entity. Such axiom is, for in­stance, . ( a = * ( a h) ) = • l«N)^(N«) ) = (a = * (\= a))) or also the pair of axioms ((a h) = » (h «)) =* (((h «)=^( 4 «)) =* a H => (« N «))); ((a \=) = • (\= a)) => (lh)^(«hh)) (a hh «))) The general scheme for the implicative rule (1.3) becomes («=•/?)= » ((/3 => 7 ) => (« = * 7)); /3,7 G {a |=, |= a, a F a , ( a F ; F a) } etc , in the sense of the previous examples (I.l) and (1.2). Thus, the informational version of the last svstem becomes / / pa , a = ^ /?G< a p a, ^ C« NA \ H,N«JJy/ // / /3es 7 € < \\\ / / \\\ P a, 7 G • p a, a p a, =>• (N4 \ /a , \ \ a p , P a, P a, = • a p a, a p a, ((<*, \ a |=, a |=, P a, P a, a (= a, =>• o; (= a, It h; )J (a\ =;) a Evidently, from this axiomatic scheme, a "com­plete" implicative circular formula proceeds: A.P. Zeleznikar {a =>. (a p)) = • (((P a ) = > (a p a)) (a|=;|=a)=>a) ) This formula is in no way an impossible specula­tion since ali operands are only different pheno­menal forms of one and the same informational entity a (with exception of the first and the last operand which are equal). 4.2.2 Another Form of "Implication" Axioms of the Informational Calculus Informational calculus bases on the informing of entities and not solely on the logical truth". As the reader can observe, the discussed propositi­onal and predicate axioms are always identically true logical formulas. We can show how other in­formational axioms which do not base on proposi­tional and predicate axioms can be derived intui­tiven, trivially and formally in the same manner as the preceding informational axioms. So let us take the syntactically rearranged axiom (I.l) in the form (a=>/3) a instead of a ==>• (/3 ==>• a). Propositional for­mula (A —• B) —> A is not an identically true formula and its value is A. Axiom (I.l) is called the axiom of the conseguent determination. What could the rearranged axiom mean at ali? Let us check its meaning by some basic examples. Let us look the semantic difference between for­mulas a (a |=) =$• a ) and («N» , a a If the first formula says that any informational entity a implies its extemalistic informing a \= as a reason of itself, the second formula stresses that any informational entity a is implied by an implication in which entity a implies its externa­hstic informing a \=. The reader will agree that it is practically impossible to argue against this ar­gument ation. In informational cases we do stric­tly distinguish between circular and serially non-circular cases. As soon as a |= appears within the cycle a ==>• ((a p ) =>• a), the transition a =L• (a p ) represents a part of the "whole hi­story" of the cycle and, therefore, can or must be considered within the form (a =>• (a [=)) = > a. Thus, another substantial implication comes to the surface: (a = • ((a |=) = • a)) = > ((a = • ( a |=)) = > a) Possibly, this fact becomes evident by the formula ( a =>• 3a) => a where 3 a expresses the entire phenomenalistic na­ture of a's informing, that is, its hermeneutics (a kind of regular interpretation of a's history) which considers not only the history of both appe­aring components a and 3 a , but also transition a =>-3a (or 3a ==>• a in the first čase). 4.2.3 "Conjunction" Axioms of the Informational Calculus Let us draw an informational parallel to the pro­positional conjunction axioms (II. 1-3) in Subsec­tion 3.2. Wha t could be the conjunction in an informa­tional sense? How could it be generalized? The logical "and", represented by operator A, means also "and simultaneously" or "in paral­lel". Informational operator of parallelism is ||= or, commonly, semicolon ';'• Thus, for the first axiom of conjunction (II.l) there is, informatio­nally, (a\\=/3)=>a or (f\=><* ­ and for the second axiom of conjunction (II.2), (a |t= /3) = > /3 or ("A = • /3 For the third axiom of conjunction (II.3.) there is («=>/?)= * ((a = > 7 ) =j> (a = • (/3 |h 7))) or, in a common informational form, ( a = > /3) = • L = • 7 ) = * L = • f #J ) The sense of parallelism axioms is significant in cases of the so-called informational decomposition (see Section 7). Two characteristic cases are, for example, 4.2.4 "Disjunction" Axiom s of the Informational Calculus Disjunction axioms (III. 1-3) in Subsection 3.2 introduce the meaning of informational formula «i> «2? •. • • j an where commas are used instead of semicolons. What does, in an informational for­mula, a comma mean at ali? Informationally, propositional axiom (III. 1) can be interpreted as a=>(a,p) Instead of propositional formula A V B there is in­formationally, simply a, (3 where the last formula just lists two alternatives which are a and /3. Al­ternatives are informational entities which can be chosen by an informational system. From which point of the philosophy could the discussed alternativeness come from? In an exter­nalistic čase, a |=, intuitively, a presumption a \= /3 exists, otherwise the externalism of a would not perform meaningfully. One can agree that from the process represented by formula a \= /3 ope­rands a and /3 can be listed. Thus, (a\=P)=>(a,P) and (a |=) = * (a,/3) Through this demonstration the step towards the "disjunction" axiom in informational calculus be­ comes evident. According to propositional axiom (III.2), there is /3=*(a,/3 ) which is another form of the first disjunction in­ formational axiom. It is not meant that the list a, /3 is ordered. Finally, according to propositional axiom (III.3), we have ( a = > 7) =>• ((/? =>. 7) = > (a,/3 =$> 7)) In the last axiom we have to explain formula a, P =>• 7 additionally; the meaning is the fol­lowing: (a,/3=^ 7 )-(^^ ) and (a,p)^{a,P} Thus, a list a, /3 connected with an operator in a formula results into a parallel system. In general, •K/s h T)-(L[:? ) ™i K//N)-(;f) This short discussion rounds up the possibilities of construction to the propositional disjunctive axi­oms parallel informational axioms. 4.2.5 "Equivalence" Axioms of the Informational Calculus The reader might observe that we have never de­fined a rigorous informational formula by which informational operator of implication, => , would be defined once for ali. In [10], only verbal possibi­lities of the informational contents of implication have been listed. On the other hand, propositio­nal implication, —•, is defined by a kind of logical table once for ali. Does it mean that the contents (not a rough definition itself) of informational im­plication changes (arises) from čase to čase? The answer might be the following: operator =>• is a regular informational operator which, from čase to čase, can (must) be particularized and univer­salized, according to the involved operands. So, it must be interpreted only to the sufficient in­formational extent. The reader can imagine how complex and never ending interpretation of infor­mational implication would proceed from the ba­sis of its verbal (dictionary-like) determinations. This fact does not restrict the discussion of informational equivalence in which informational implication plays an essential role. Thus, we can put the question of informational equivalence in parallel to the existing notion of propositional cal­culus. According to the axiom group (IV. 1-3) in Sub­section 3.2, the adequate informational ,axioms concerning informational equivalence are the fol­lowing: ( a «=> /3) = > ( a =$> /3); ( a ^=> ^ ) = • (j9 = > a); (a = > /3) => ((/? => a ) = > (a <=?> /3)) Informational operator of equivalence, •*=>•, can be defined dependently on informational implica­tion, that is, according to deduction theorems of predicate calculus in Subsection 3.7. In this sense, A.P. Zeleznikar (a <=> /3) ^ De f ((a = • /3; /3 ==• a)) Thus, in each particular čase, when particulari­zing operator •$=>, this particularization depends on the particularization of implicative operator 4.2.6 "Negation" Axioms of the Informational Calculus The purpose of the negation of a statement in pro­positional calculus is to obtain the true negated statement, that is, the true otherwise false state­ment. In informational calculus, an entity informs or can be informed in a certain manner, but not in another one. This last situation can be discussed in the framework of an entity's non-informing. Thus, an informational equivalent to the propo­sitional situation A is, for example, a \L and \fi a which reads a does not inform (in a certain man­ner) and a is not informed (in a certain manner), respectivelv. Additionallv, operator \fi represents only a particular čase of operator |=. For a double negation A it is possible to distin­guish different cases of double non-informing, for instance, (aftfc &{<*&>, (fet a) fež; \L (fcfe a ) Considering the axiom group of negation (V.1-3) in propositional calculus (Subsection 3.2), there is, informationally, (a = * /3) = • ((/3 ^ /3) = » (a ft \fi a)); However, to these axioms, characteristic informa­tional axioms concerning the phenomenon of non-informing can be adopted. For example, (a = • (a h)) =^(a=^(a ^)) ; (a = » (|= a)) = • ( a =*• ( ^ a)); ( a = > ( a |= a)) = > ( a =>• (a \L a)); (a =^ (a |=; \= a)) ^(a^(a^; ^ a)) etc. concern operator particularization in the pro­cesses of decomposition. 4.2.7 "Predicate" Axioms and Theorems of the Informational Calculus The universal and existential quantifi.er do not play a significant role in the informational calcu­lus. They are rather very uncommon entities wi­thin the informational realm. For instance, ope­rator |= ve* reads informs (is informed) for ali a 's and formulas o r a " |=for_all_a \=Va] |=for_all_a « Or \=Va &; « Nor-all_a « Or. a\=yaOL\ O Nor-all^a! |=for^,U_a « Or O \=~ia\ \=\/a a are very special cases since it is not clear to which informational realm the 'ali' could refer. A simi­lar, problematic situation occurs in the čase of the existential quantifier where formulas o r a a |=exist_a t=3« ; Kxist ^ a or \=3aa; ot |=exist_a « or a |=3 a a; C F=exist_aj r=existja & Or OL |=3a!) p1 3a ® Analogously to the predicate axiom group (VI. 1­2) in Subsection 3.5, the adequate informational axioms could take the form V(^)=> (« Na« Y>(«)) The reader can imagine how the operator attri­bute for ali a 's- in an informational realm causes that the informational function (p is informatio­nally impacted by (3 which is within the realm of aH a, etc. On the other hand, informational function /3 ) The theorems of predicate calculus in Subsec­tion 3.7 become, informationallu, Informatica 19 (1995) 345-370 357 -*((a Nv« tp(a)) ==> (a \=3a (<*,/?))) «=> (P hv,e (a |= v« Y>(<*,/?))); (a\=3a(/3 \=v0 ((3 \=vp(a\=3a v(a,/3))); -»((a Nvcv (v(a ) =>• ^(a))) => ((a |= V a (")) = > ( a Nv« ^(«)))); -»((a |=Va (v(a ) =>• V»(a))) => ((a 1=3« (a ^ 3 a ^(«)))); -»((a hv a ( ((a ^v a Y>(«)) ^=^ (« hv a ^(")))); (a t=3a (a ^ a (y?(a) \L; ^ (p(a))); (a|^ a(^(a)^^(«))); (ah»W«)^;^W)); («|=3a (v(a) b^; b^ y(«))) <=>• O Nvc Y»(«)) D These theorems can cause a retrograde and logi­cally more critical understanding of the predicate theorems listed in Subsection 3.7. 4.3 The Variety of Informational Axioms of Inference One of the basic questions concerning the infe­rence schemes in different calculuses is in which manner inference rules are constructed and accep­ted by scientific communities. Obviously, the way to various inference rules leads through the un­derstanding of the basic axioms treated in the preceding subsections. An inference rule is no­thing else than a means for the derivation (de­duction) process where it is used for a construc­tive transformation of theory-legal formulas into new formulas. The next step concerning axioms and inference rules is the introduction of the so-called replacement rules by which formulas can be transformed automatically, e.g. in a machine-like fashion. Informational rules of inference function like axioms and only by them it is permitted to con­clude in a theory-consistent manner. E.g., rules of substitution and modus ponens belong to the most obvious and widely accepted rules for for­mula transformation within a deduction process. On the other hand, informational inference rules can cover informationalb/ unlimited possibilities and they can come into existence together with specific and particular informational problems. The so-called modi informationis [6] can.be gro­uped and expressed in several possible ways. We have the following possibilities: 1. Modus ponens is the most obvious inference rule in mathematics in the realm of truth. Infor­mational modus ponens follows the general (phe­nomenalistic) principle of informing where the mathematical to be true is replaced by the infor­mational to inform. This does not mean that the true is excluded, it only appears as a particular čase of the informational. In this sense, informa­tional modus ponens as an inference rule retains the basic logical form which is a;(a=> /?) and where the implicational operator =>• has a broadened meaning in comparison with the logical implication operator —>, determined, for example, by a logical table. Implicit informational operator of parallelism ';' which simultaneously performs as a formula separator replaces the logical opera­tor A (also, a comma in the traditional inference rule). Particularizations of modus ponens can appear as special rules called, for example, modus proce­dendi, modus operandi and others. 2. Modus tollens is a rule of a reverse inferring in respect to the implication formula of its pre­mise. There is a truly substantial difference be­tween the mathematical and informational modus tollens. In the domain of truth, the falsity is the only essential counterpart to the truth and, so, the operator of negation of a formula becomes truly essential. Through the introduction of negation it becomes possible to express the falsity of a sta­tement as its truth (e.g., identically true falsity). In informational modus tollens the negation is replaced by the operator of noninforming (in a certain way), denoted by \L. The reader can now feel the dramatic difference existing betvreen a static state of negation and the dynamic state of noninforming concerning a logical and an in­formational entity, respectively. Thus, the infor­mational modus tollens in comparison with the logical one keeps the form A.P. Zeleznikar (a = » /3); (/3 fr & /3) a\L;\La with already mentioned differences concerning the modus ponens. 3. Modus rectus is not a mathematical inference rule and its origin can be searched in the analysis of the Latin speech. The aim of this rule is the filtering-out (detaching) of the intention marked by iintention(Q;)> hidden in entity represented by a through the informing of a, e.g. to an entity represented by /3. It is understood that this in­tention is an informational function of a which is reflected in /3 to which a informs intentionally (or in an intending manner, that is, 'intendingly'). In this sense, apossibility of informational modus rectus becomes O? ((<* Nintend P) => *intention( Op) (iintention(Q!) N i h MntentionC«)) C /3 One can certainly construct 'intentional' rules where the intention or an intention-like entity (functional operand) performs in a certain man­ner, so, its detachment becomes possible. 4. Modus obliquus belongs to the most conten­tious inference rules because it usually proceeds from an absurd situation where the inference from a contradictory situation suggest to use the rule for an achievement of the logically consistent re­sult. From a deceitful situation just the absurd inference should help to reach a firm conclusion. In fact, modus obliquus belongs to the so-called discursive informing where through a discourse (as communication, informing, reasoning) by ali possible logical tricks, including absurd, contra­diction, controversial informing, a valuable con­clusion should be detached. In this sense, modus obliquus becomes a discursive filter delivering a useful result. In this sense, one of its possible schemes could be »absurd(a ) C