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1 2

1 1 n ¨1 ¨2

2

3

a, a(a≧a)

4 1 n (Turing Machine) 1936Alan Turing Alan Turing 1912-1954

Σ: K: • •Σ •K • • 5 2 RAM (Random Access Machine)

()

¨ ¨ ¨

6

M=(K,Σ,δ,s) K s∈K Σ K∩Σ=`␣’`’ `␣’ `␣’ δKΣ → K∪{h,``yes’’,``no’’})Σ{←,→,}, h: halting state () yes: accepting state ( no: rejecting state ( ←: →: : δ(q, )=(p, ,→) 7 01

M=(K,Σ,δ,s), K={s,q,q0,q1}, Σ={0,1, ␣,} δ(s,0)=(s,0,→) δ(s,1)=(s,1,→) δ(s, ␣)=(q, ␣,←) 010 010 010 010 δ(s, )=(s, ,→) s s s s δ(q,0)=(q0, ␣,→) δ(q,1)=(q , ␣,→) 1 010␣ 010␣ 01␣␣ 01␣0 δ(q, ␣)=(q, ␣,) δ(q, )=(h, ,→) s q q0 s δ(q0,0)=(s,0,←) δ(q0,1)=(s,0,←) 01␣0 0␣␣0 0␣10 0␣10 δ(q0, ␣)=(s,0,←) q q1 s q δ(q0, )=(h, ␣,→) δ(q1,0)=(s,1,←) 10 010 010 010 δ(q1,1)=(s,1,←) ␣␣ ␣ ␣ ␣ δ(q , )=(s,1,←) 1 ␣ q0 s q h δ(q1, )=(h, ␣,→) 8 Σ*Σ

def Σ*f ⇔ x∈Σ* Mxf(x) M

δKΣk → K∪{h,``yes’’,``no’’})Σk{←,→,}k

δKΣ → 2K∪{h,``yes’’,``no’’})Σ{←,→,}

2XXX 9 ChurchChurch-Turing)(1936)

Alonzo Church, 1903-1995, f ⇔ fλ ⇔ f Gödel Church Turing Church, Kleene Turing

λ

(λ)

10

• →YES

• Mp

Mp x(p,x)Mx

11

Mpx(p,x) Mx halt

halt(p,x)= 1 if p x 0 otherwise

halt

12 halt

halt haltM

M Mp if(halt(u,u)=1) { while(true){ u←u;} M(u=)p } else { ⇒halt(p,p)=1 return(0); ⇒Mp } ()

M(u=p) ⇒halt(p,p)=0 ⇒Mp

halt

13

14 1966(ACM) 2007 Edmund M. Clarke 2003 E. Allen Emerson LSI 2004 Vinton G. Cerf Robert E. Kahn TCP/IP

2005 Algol 60 2008 () 2006 Frances E Allen ( CLUArgus 2010 Leslie G. Valiant 2009 Charles P. Thacker 2011 Alto PC 2012 , 2013 URL: https://amturing.acm.org/byyear.cfm 2014 2015 , 2016 Berners-Lee, Tim World Wide Web (WWW) 2017 John L. Hennessy, David Patterson 2018 , Geoffrey E Hinton, Yann LeCun 2019 Edwin E. Catmull (*1), Patrick M. Hanrahan (CG)15 (*1 ACM EATCS 5,000

2 Kurt Gödel, 2004 , Michael Saks, and : applications of topology to the theory of 1906-1978, 2005 , and : their foundational contribution to streaming 2006 , , : the AKS 2007 , : natural proofs 2008 , Shanghua Teng: of algorithms 2009 , , : zig-zag product of graphs and undirected connectivity in log space 2010 , Joseph S. B. Mitchell: their concurrent discovery of a polynomial-time approximation scheme (PTAS) for the Euclidean Travelling Salesman Problem (ETSP) 2011 Johan Håstad: proving optimal inapproximability result for various combinatorial problems 2012 , , , Amir Ronen, and Éva Tardos: laying the foundations of algorithmic 2013 , Matthew K. Franklin, and : for multi-party Diffie–Hellman exchange and the Boneh–Franklin scheme in 2014 , Amnon Lotem, and : for Optimal Aggregation Algorithms for Middleware 2015 Daniel Spielman, Shanghua Teng or their series of papers on nearly-linear-time Laplacian solvers #P1998 16 Fields Medal(1936-)Carl Friedrich Gauss Prize(2006-) 4 40 15,000IMU) Rolf Nevanlinna, 1895-1980, Year Laureate Nationality 1982 1986 United Kingdom 1990 Alexander Razborov Russia 1994 Avi Wigderson 1998 United States 2002 / United States 2006 United States 2010 Daniel Spielman United States 2014 india/ United States John von Neumann (1992-) 4000 (IEEE) 1990 3von Neumann 17