1610906281-d25a58898a45262b0b837c281ba962eb (824376), страница 12
Текст из файла (страница 12)
Ôîðìàëèçàöèè ïîíÿòèÿ âû÷èñëèìîé ôóíêöèèÄîêàçàòåëüñòâî. Ñëåäóåò èç ëåììû 18 è ñëåäóþùèõ òîæäåñòâ:XP &Q (x) = XP (x) · XQ (x),XP ∨Q (x) = sg(XP (x) + XQ (x)),X¬P (x) = sg(XP (x)),XP →Q (x) = X¬P ∨Q (x) = sg(sg(XP (x)) + XQ (x)).Ïðåäëîæåíèå 22.Áèíàðíûå îòíîøåíèÿ =, 6=, <, >, 6, > ÿâëÿþòñÿ ïðèìèòèâíîðåêóðñèâíûìè.Äîêàçàòåëüñòâî.
Ïðèìèòèâíàÿ ðåêóðñèâíîñòü äàííûõ îòíîøåíèé ñëåäóåò èç ëåììû18 è òîæäåñòâX= (x, y) = sg|x − y|,X< (x, y) = sg(y−x),X6 (x, y) = sg(x−y),X6= (x, y) = sg|x − y|,X> (x, y) = sg(x−y),X> (x, y) = sg(y−x).Åñëè îòíîøåíèå R(x, i) ðåêóðñèâíî (ïðèìèòèâíî ðåêóðñèâíî),òî îòíîøåíèÿ ∃i 6 y R(x, i), ∀i 6 y R(x, i), ∃i < y R(x, i), ∀i < y R(x, i) òîæåðåêóðñèâíû (ïðèìèòèâíî ðåêóðñèâíû).Äîêàçàòåëüñòâî. Óòâåðæäåíèå äëÿ îòíîøåíèÿ P (x, y) = ∃i 6 y R(x, i) ñëåäóåò èçÏðåäëîæåíèå 23.ëåììû 19 è òîæäåñòâàXP (x, y) = sgyXXR (x, i) .i=0Óòâåðæäåíèå äëÿ îñòàëüíûõ îòíîøåíèé âûòåêàåò èç ïðåäëîæåíèé 21, 22 è ýêâèâàëåíòíîñòåé∀i 6 y R(x, i) ⇐⇒ ¬∃i 6 y ¬R(x, i),∃i < y R(x, i) ⇐⇒ ∃i 6 y(R(x, i) & i 6= y),∀i < y R(x, i) ⇐⇒ ¬∃i < y ¬R(x, i).Ïóñòü R0, . .
. , Rk ⊆ ωn ðåêóðñèâíûå (ïðèìèòèâíî ðåêóðñèâíûå) îòíîøåíèÿ, òàêèå, ÷òî R0 ∪ . . . ∪ Rk = ωn èRi ∩ Rj = ∅ ïðè i 6= j . Ïóñòü äàëåå f0 (x1 , . . . , xn ), . . . , fk (x1 , . . . , xn ) ðåêóðñèâíûå(ïðèìèòèâíî ðåêóðñèâíûå) ôóíêöèè. Òîãäà ôóíêöèÿf0 (x), åñëè R0 (x),Ïðåäëîæåíèå 24(î êóñî÷íîì çàäàíèè ôóíêöèè).F (x) =······fk (x),åñëè Rk (x)òîæå ðåêóðñèâíà (ïðèìèòèâíî ðåêóðñèâíà).Äîêàçàòåëüñòâî.
Äîñòàòî÷íî çàìåòèòü, ÷òî F (x) = f0(x)·XR (x)+. . .+fk (x)·XR (x).0k 13. Ðåêóðñèâíîñòü íåêîòîðûõ ôóíêöèé è îòíîøåíèéËåììà 25.49Åñëè ôóíêöèÿ g(x, y) ðåêóðñèâíà (ïðèìèòèâíî ðåêóðñèâíà), òî ôóíêöèÿh(x, y, z) =Qz g(x, i),i=y1,åñëè y 6 z,åñëè y > z,òîæå ðåêóðñèâíà (ïðèìèòèâíî ðåêóðñèâíà).Äîêàçàòåëüñòâî.
(Ïðèìèòèâíàÿ) ðåêóðñèâíîñòü ôóíêöèè h ñëåäóåò èç ëåììû 19,ïðåäëîæåíèÿ 24 è ñëåäóþùåé êóñî÷íîé ñõåìû: Qyz−g(x, y + i),h(x, y, z) = i=01,åñëè y 6 z,åñëè y > z.Ïóñòü R(x, y) îòíîøåíèå, h(x) âñþäó îïðåäåë¼ííàÿ ôóíêöèÿ.Îáîçíà÷èì ÷åðåç µy[R(x, y)] ôóíêöèþ µy[|XR (x, y)−1| = 0], à ÷åðåç µy 6 h(x)[R(x, y)]îáîçíà÷èì ôóíêöèþ µy 6 h(x)[|XR (x, y) − 1| = 0]. ßñíî, ÷òî åñëè R(x, y) ðåêóðñèâíî,òî µy[R(x, y)] ÷.ð.ô. Êðîìå ýòîãî, èç ïðåäëîæåíèÿ 20 ñëåäóåò, ÷òî åñëè R(x, y) èh(x) ïðèìèòèâíî ðåêóðñèâíû, òî µy 6 h(x)[R(x, y)] ï.ð.ô.Îïðåäåëåíèå.à) Ôóíêöèÿ [ xy ], ðàâíàÿ öåëîé ÷àñòè îò ÷àñòíîãî xy , ïðèìèòèâíî ðåêóðñèâíà (ïî îïðåäåëåíèþ ñ÷èòàåì, ÷òî [ x0 ] = x).á) Îòíîøåíèå Div(x, y), èñòèííîå òîãäà è òîëüêî òîãäà, êîãäà x äåëèò y, ïðèìèòèâíî ðåêóðñèâíî.â) Îòíîøåíèå Prime(x), èñòèííîå òîãäà è òîëüêî òîãäà, êîãäà x ïðîñòîå÷èñëî, ïðèìèòèâíî ðåêóðñèâíî.Äîêàçàòåëüñòâî.
Äîêàæåì óòâåðæäåíèå ïóíêòà (à). Èìååò ìåñòî öåïî÷êà ýêâèâàËåììà 26.ëåíòíîñòåé [x/y] = z ⇐⇒ (y = 0 & x = z) ∨ (y 6= 0 & z 6 x/y < z + 1) ⇐⇒(y = 0 & x = z) ∨ (y 6= 0 & zy 6 x < (z + 1)y) ⇐⇒ (y = 0 & x = z) ∨ (y 6=0 & z íàèìåíüøåå, òàêîå, ÷òî x < (z + 1)y). Êðîìå ýòîãî, ÿñíî, ÷òî [x/y] 6 x. Îòñþäà ïîëó÷àåì:hi[x/y] = µz 6 x (y = 0 & x = z) ∨ (y 6= 0 & x < (z + 1)y) .Òàêèì îáðàçîì, ôóíêöèÿ [x/y] ïîëó÷åíà îãðàíè÷åííîé ìèíèìèçàöèåé èç ïðèìèòèâíîðåêóðñèâíûõ ôóíêöèé, à çíà÷èò, ÿâëÿåòñÿ ï.ð.ô.Óòâåðæäåíèÿ ïóíêòîâ (á) è (â) ñëåäóþò èç ýêâèâàëåíòíîñòåé:Div(x, y) ⇐⇒ ∃z 6 y(xz = y)Prime(x) ⇐⇒ (x > 2) & ∀y 6 x Div(y, x) −→ (y = 1 ∨ y = x) .à) Ôóíêöèÿ p(x) = px, ãäå p0 = 2, p1 = 3, p2 = 5, .
. . ïåðå÷èñëåíèåâñåõ ïðîñòûõ ÷èñåë â ïîðÿäêå âîçðàñòàíèÿ, ÿâëÿåòñÿ ïðèìèòèâíî ðåêóðñèâíîé.Ëåììà 27.50Ãëàâà III. Ôîðìàëèçàöèè ïîíÿòèÿ âû÷èñëèìîé ôóíêöèèá) Ôóíêöèÿ ex(i, x), ðàâíàÿ ïîêàçàòåëþ ñòåïåíè pi â êàíîíè÷åñêîì ðàçëîæåíèè÷èñëà x íà ïðîñòûå ìíîæèòåëè, ÿâëÿåòñÿ ïðèìèòèâíî ðåêóðñèâíîé (çäåñüex(i, 0) = 0).â) Ôóíêöèÿ long(x), ðàâíàÿ íîìåðó íàèáîëüøåãî ïðîñòîãî äåëèòåëÿ ÷èñëà x, ÿâëÿåòñÿ ïðèìèòèâíî ðåêóðñèâíîé (çäåñü long(0) = long(1) = 0).Äîêàçàòåëüñòâî. à)  ñèëó òåîðåìû ×åáûø¼âà, óòâåðæäàþùåé, ÷òî äëÿ ëþáîãî n >1 ñðåäè ÷èñåë n+1, n+2, . . . , 2n íàéä¼òñÿ õîòÿ áû îäíî ïðîñòîå, çàêëþ÷àåì, ÷òî èìååòìåñòî îöåíêà px+1 6 2px .Îòñþäà ñëåäóåò, ÷òî ôóíêöèþ p(x) = px ìîæíî ïîëó÷èòü ïî ñõåìå ïðèìèòèâíîéðåêóðñèè(p0 = 2,px+1 = µy 6 2px Prime(y) & y > px ,òî åñòü p(x) ïîëó÷åíàïðèìèòèâíîé ðåêóðñèè èç ôóíêöèé g = 2 ñ ïîìîùüþ îïåðàòîðàè h(x, z) = µy 6 2z Prime(y) & y > z , ãäå ôóíêöèÿ h(x, z) â ñâîþ î÷åðåäü ïîëó÷åíà ñ ïîìîùüþ îãðàíè÷åííîé ìèíèìèçàöèè èç ïðèìèòèâíî ðåêóðñèâíûõ ôóíêöèé èïðåäèêàòîâ.Òàê êàê ó÷àñòâóþùèå â ñõåìå ôóíêöèè g è h(x, z) ïðèìèòèâíî ðåêóðñèâíû, òîp(x) ÿâëÿåòñÿ ï.ð.ô.ex(i,x)6 x.
Ïîýòîìóá) Çàìåòèì, ÷òî ñïðàâåäëèâû íåðàâåíñòâà ex(i, x) < 2ex(i,x) 6 piôóíêöèÿ ex(i, x) ïîëó÷àåòñÿ ñ ïîìîùüþ îãðàíè÷åííîé ìèíèìèçàöèèex(i, x) = µy 6 x[¬Div(py+1, x) ∨ x = 0].iâ) Çàìåòèì, ÷òî åñëè ïðîñòîå ÷èñëî pi âõîäèò ñ íåíóëåâûì ïîêàçàòåëåì â êàíîíè÷åñêîå ðàçëîæåíèå ÷èñëà x > 1, òî i < pi 6 x. Ïîýòîìó ôóíêöèÿ long(x) ïîëó÷àåòñÿñ ïîìîùüþ îãðàíè÷åííîé ìèíèìèçàöèèlong(x) = µy 6 x[x 6 1 ∨ ∀i 6 x(i > y −→ ex(i, x) = 0)]. 14.Êîäèðîâàíèå ìàøèí ÒüþðèíãàÌû ïîñòåïåííî ïðèáëèæàåìñÿ ê äîêàçàòåëüñòâó òåîðåìû î òîì, ÷òî ëþáàÿ ôóíêöèÿ, âû÷èñëèìàÿ íà ìàøèíå Òüþðèíãà, ÿâëÿåòñÿ ÷àñòè÷íî ðåêóðñèâíîé.
Îñíîâíàÿèäåÿ äîêàçàòåëüñòâà ýòîé òåîðåìû çàêëþ÷àåòñÿ â ñëåäóþùåì: ìû çàêîäèðóåì âñåâû÷èñëåíèÿ íà ìàøèíàõ Òüþðèíãà íàòóðàëüíûìè ÷èñëàìè òàêèì îáðàçîì, ÷òî âñåíåîáõîäèìûå îïåðàöèè ñ ïîëó÷åííûìè êîäàìè (ò. å. îïåðàöèè, èìèòèðóþùèå ðàáîòóìàøèíû) ìîæíî áóäåò ïðîèçâîäèòü ñ ïîìîùüþ ÷àñòè÷íî ðåêóðñèâíûõ ôóíêöèé. Âýòîì ïàðàãðàôå áóäåò ôîðìàëüíî îïèñàí ìàòåìàòè÷åñêèé àïïàðàò, ðåàëèçóþùèé ýòóèäåþ. Íàì ïðåäñòîèò çàêîäèðîâàòü íàòóðàëüíûìè ÷èñëàìè ìàøèííûå ñëîâà, êîìàíäû, ïðîãðàììû è, íàêîíåö, ïðåîáðàçîâàíèÿ ìàøèííûõ ñëîâ íà ìàøèíàõ Òüþðèíãà.Âñå èñïîëüçóåìûå íèæå êîäû îñíîâàíû íà ñëåäóþùåì ñïîñîáå îäíîçíà÷íîãî êîäèðîâàíèÿ êîðòåæåé íàòóðàëüíûõ ÷èñåë ïðîèçâîëüíîé äëèíû.
Åñëè hx0 , . . . , xk i êîíå÷íàÿ ïîñëåäîâàòåëüíîñòü ýëåìåíòîâ ω , òî å¼ñëóæèò íàòóðàëüíîå ÷èñëîpx0 0 +1 ·px1 1 +1 ·. . . ·pxkk +1 . Êîäîì ïóñòîé ïîñëåäîâàòåëüíîñòè áóäåì ñ÷èòàòü ÷èñëî 1. Åñëèêîäîì 14. Êîäèðîâàíèå ìàøèí Òüþðèíãà51x êîä íåêîòîðîãî êîðòåæà, òî ìîæíî ýôôåêòèâíî íàéòè åãî äëèíó êàê long(x) + 1,è âîññòàíîâèòü âñå åãî ýëåìåíòû êàê ex(i, x)−1, ãäå 0 6 i 6 long(x).Çàìåòèì òàêæå, ÷òî åñëè äëèíà ðàññìàòðèâàåìûõ êîðòåæåé ôèêñèðîâàíà, òî ìîæíî íå ïðèáàâëÿòü åäèíèöû â ïîêàçàòåëÿõ ñòåïåíåé ïðîñòûõ ÷èñåë, ò.å. â ýòîì ñëó÷àåêîä âèäà px0 0 · px1 1 · .
. . · pxk k òîæå áóäåò îäíîçíà÷íûì.Ïóñòü A ïðîèçâîëüíîå (âîçìîæíî ïóñòîå) ñëîâî â ñ÷¼òíîì àëôàâèòå {a0 , a1 , a2 , . . .}, ïðè ýòîì ìû ñ÷èòàåì, ÷òî a0 = 0, a1 = 1. ÎïðåäåëèìbAcl èbAcrA ñëåäóþùèì îáðàçîì:Îïðåäåëåíèå.ïðàâûé êîäëåâûé êîäñëîâà(1,bAcl =1 +1. . . p0ik +1 ,pik0 +1 pik−1(1,bAcr =pi00 +1 pi11 +1 .
. . pkik +1 ,åñëè A = Λ,åñëè A = ai0 ai1 . . . aik .åñëè A = Λ,åñëè A = ai0 ai1 . . . aik .Êîäîì ìàøèííîãî ñëîâàÎïðåäåëåíèå.M = Aqi aj B , ãäå qi ∈ {q0 , q1 , . . .}, aj ∈{a0 , a1 , . . .}, A, B ∈ {a0 , a1 , . . .}∗ íàçûâàåòñÿ ÷èñëîbM c = 2bAcl · 3i · 5j · 7bBcr .Îïðåäåëåíèå.Êîäîì êîìàíäû T (i, j) = qiaj → qk al S , ãäå i > 1, j > 0, k > 0, l > 0,S ∈ {Λ, L, R} íàçûâàåòñÿ ÷èñëîk l sbT (i, j)c = p22i 33j 5 ,ãäå s = 0, åñëè S = Λ; s = 1, åñëè S = L; è s = 2, åñëè S = R.Ïóñòü T = h{a0 , .
. . , an }, {q0 , . . . , qm }, P, q1 , q0 i ìàøèíà Òüþðèíãà ñïðîãðàììîé P = {T (i, j) | 1 6 i 6 m, 0 6 j 6 n}.T íàçûâàåòñÿïðîèçâåäåíèå êîäîâ âñåõ å¼ êîìàíä, ò.å. ÷èñëîÎïðåäåëåíèå.Êîäîì ìàøèíûbT c =YbT (i, j)c.16i6m06j6nÎïðåäåëåíèå.Ôóíêöèåé îäíîøàãîâîãî ïðåîáðàçîâàíèÿ êîäîâ ìàøèííûõ ñëîâ íàçî-â¼ì ëþáóþ âñþäó îïðåäåë¼ííóþ ôóíêöèþ f (t, w), óäîâëåòâîðÿþùóþ óñëîâèþ: åñëèt = bT c, ãäå T íåêîòîðàÿ ìàøèíà Òüþðèíãà, w = bM c, ãäå M ìàøèííîå ñëîâîâ àëôàâèòå ìàøèíû T , òîf (t, w) = bMT0 c.Ñóùåñòâóåò ï.ð.ô. step(t, w), êîòîðàÿ ÿâëÿåòñÿ ôóíêöèåé îäíîøàãîâîãî ïðåîáðàçîâàíèÿ êîäîâ ìàøèííûõ ñëîâ.Äîêàçàòåëüñòâî.
Ïóñòü t ÿâëÿåòñÿ êîäîì íåêîòîðîé ìàøèíû T , à w êîäîì íåêîòî-Ïðåäëîæåíèå 28.ðîãî ìàøèííîãî ñëîâà â àëôàâèòå ìàøèíû T . Ñëåäîâàòåëüíî w = 2u ·3i ·5j ·7v , ãäå qiâõîäèò â àëôàâèò âíóòðåííèõ ñîñòîÿíèé äàííîé ìàøèíû, aj âõîäèò â å¼ âíåøíèéàëôàâèò, u ëåâûé êîä íåêîòîðîãî ñëîâà A âî âíåøíåì àëôàâèòå, à v ïðàâûé êîòíåêîòîðîãî ñëîâà B âî âíåøíåì àëôàâèòå.52Ãëàâà III. Ôîðìàëèçàöèè ïîíÿòèÿ âû÷èñëèìîé ôóíêöèèÏàðàìåòðû i, j, u, v ìîæíî âû÷èñëèòü ñ ïîìîùüþ ñëåäóþùèõ ï.ð.ô., çàâèñÿùèõîò àðãóìåíòà w:i(w) = ex(1, w),j(w) = ex(2, w),u(w) = ex(0, w),v(w) = ex(3, w).Ðàññìîòðèì ñëåäóþùèå øåñòü ñëó÷àåâ, â êàæäîì èç êîòîðûõ ìû îïðåäåëèì çíà÷åíèå step(t, w) = b(Aqi aj B)0T c.(1) Ïóñòü i = 0. Òîãäà qi = q0 è òåêóùåå ñîñòîÿíèå ìàøèíû T ÿâëÿåòñÿ êîíå÷íûì.Ñëåäîâàòåëüíî (Aqi aj B)0T = Aqi aj B , è â äàííîì ñëó÷àåstep(t, w) = f1 (t, w) = 2u(w) · 30 · 5j(w) · 7v(w) .Åñëè i > 0, òî â ïðîãðàììå ìàøèíû T íàéä¼òñÿ êîìàíäà T (i, j) = qi aj → qk al S ,k l sêîòîðàÿ áóäåò èñïîëíÿòüñÿ â äàííûé ìîìåíò.
Ïîñêîëüêó êîä p22i 33j 5 äàííîé êîìàíäûâõîäèò â êîä t ìàøèíû T , òî ïàðàìåòðû k, l, s ìîæíî âû÷èñëèòü ñ ïîìîùüþ ñëåäóþùèõ ï.ð.ô.:k(t, w) = ex(0, ex(2i(w) 3j(w) , t)),l(t, w) = ex(1, ex(2i(w) 3j(w) , t)),s(t, w) = ex(2, ex(2i(w) 3j(w) , t)).(2) Ïóñòü i > 0, s = 0. Òîãäà êîìàíäà T (i, j) èìååò âèä qi aj → qk al .
Ñëåäîâàòåëüíî(Aqi aj B)0T = Aqk al B , è â äàííîì ñëó÷àåstep(t, w) = f2 (t, w) = 2u(w) · 3k(t,w) · 5l(t,w) · 7v(w) .(3) Ïóñòü i > 0, s = 1, u = 1. Òîãäà êîìàíäà T (i, j) èìååò âèä qi aj → qk al L èïðèìåíÿåòñÿ ê ìàøèííîìó ñëîâó M = qi aj B . Ñëåäîâàòåëüíî (M )0T = qk a0 al B , è âäàííîì ñëó÷àåstep(t, w) = f3 (t, w) = 21 · 3k(t,w) · 50 · 7gr (t,w) ,ãäå gr (t, w) = bal Bcr = 2l(t,w)+1 ·long(v(w))Qex(e,v(w))pe+1.e=0(4) Ïóñòü i > 0, s = 1, u > 1.
Òîãäà êîìàíäà qi aj → qk al L ïðèìåíÿåòñÿ êìàøèííîìó ñëîâó M = Aqi aj B , ïðè÷¼ì ñëîâî A = A0 ap íå ïóñòî. Ñëåäîâàòåëüíî(M )0T = A0 qk ap al B , ãäå p = ex(0, u(w))−1. Òàêèì îáðàçîìstep(t, w) = f4 (t, w) = 2hl (w) · 3k(t,w) · 5ex(0,u(w))−1 · 7gr (t,w) ,ãäå hl (w) = bA cl =0long(u(w))−Q 1ex(e+1,u(w))pe, à ôóíêöèÿ gr (t, w) òàêàÿ æå êàê âûøå.e=0(5) Ïóñòü i > 0, s = 2, v = 1. Òîãäà êîìàíäà qi aj → qk al R ïðèìåíÿåòñÿ ê ìàøèííîìó ñëîâó M = Aqi aj .
Ñëåäîâàòåëüíî (M )0T = Aal qk a0 , è â ýòîì ñëó÷àå ïîëó÷àåìstep(t, w) = f5 (t, w) = 2gl (t,w) · 3k(t,w) · 50 · 71 ,ãäå gl (t, w) = bAal cl = 2l(t,w)+1 ·long(u(w))Qex(e,u(w))pe+1.e=0(6) Ïóñòü i > 0, s = 2, v > 1. Òîãäà êîìàíäà qi aj → qk al R ïðèìåíÿåòñÿ êìàøèííîìó ñëîâó M = Aqi aj B , ïðè÷¼ì ñëîâî B = ap B 0 íå ïóñòî. Ñëåäîâàòåëüíî(M )0T = Aal qk ap B 0 , ãäå p = ex(0, v(w))−1. Òàêèì îáðàçîìstep(t, w) = f6 (t, w) = 2gl (t,w) · 3k(t,w) · 5ex(0,v(w))−1 · 7hr (w) , 14. Êîäèðîâàíèå ìàøèí Òüþðèíãàãäå hr (w) = bB cr =0long(v(w))−Q 1ex(e+1,v(w))pe53, à ôóíêöèÿ gl (t, w) òàêàÿ æå êàê âûøå.e=0Çàìåòèì, ÷òî âûøå â ðåêóðñèâíûõ ñõåìàõ, îïðåäåëÿþùèõ çíà÷åíèÿ i(w), j(w),u(w), v(w), k(t, w), l(t, w), s(t, w), f1 (t, w), .
. . , f6 (t, w), èñïîëüçóþòñÿ ïðèìèòèâíî ðåêóðñèâíûå ôóíêöèè, êîòîðûå îïðåäåëåíû íà ëþáûõ íàòóðàëüíûõ çíà÷åíèÿõ t, w, âòîì ÷èñëå íà çíà÷åíèÿõ t, w, íå óäîâëåòâîðÿþùèõ îïðåäåëåíèþ ôóíêöèè îäíîøàãîâîãî ïðåîáðàçîâàíèÿ êîäîâ ìàøèííûõ ñëîâ. Ïîýòîìó ìû ìîæåì ðàññìàòðèâàòü i(w),j(w), u(w), v(w), k(t, w), l(t, w), s(t, w), f1 (t, w), .
. . , f6 (t, w) êàê âñþäó îïðåäåë¼ííûåôóíêöèè, è çíà÷èò ïî ïîñòðîåíèþ îíè ïðèìèòèâíî ðåêóðñèâíû.Îïðåäåëèì òåïåðü äëÿ ïðîèçâîëüíûõ t, w ∈ ω çíà÷åíèå step(t, x) ïî ñëåäóþùåéêóñî÷íîé ñõåìåf1 (t, w), åñëè i(w) = 0,f2 (t, w), åñëè i(w) > 0, s(t, w) = 0,f (t, w), åñëè i(w) > 0, s(t, w) = 1, u(w) = 1,3step(t, w) =f4 (t, w), åñëè i(w) > 0, s(t, w) = 1, u(w) > 1,f5 (t, w), åñëè i(w) > 0, s(t, w) = 2, v(w) = 1,f6 (t, w), åñëè i(w) > 0, s(t, w) = 2, v(w) > 1. ñèëó ïðåäëîæåíèÿ 24, ôóíêöèÿ step(t, w) ïðèìèòèâíî ðåêóðñèâíà.