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Blum's speedup theorem

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58:). Blum's speedup theorem shows that for any complexity measure, there exists a computable function such that there is no optimal program computing it, because every program has a program of lower complexity. This also rules out the idea that there is a way to assign to arbitrary functions 368:. The fact that it may be as fast-growing as desired (as long as it is computable) means that the phenomenon of always having a program of smaller complexity remains even if by "smaller" we mean "significantly smaller" (for instance, quadratically smaller, exponentially smaller). 340: 497: 111: 362: 265: 242: 222: 202: 182: 158: 135: 451: 70:. This does of course not exclude the possibility of finding the complexity of an optimal program for certain specific functions. 51: 20: 377: 272: 50:
one often strives to find a program with the smallest complexity for a given computable function and a given
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Mathematical Foundations of Computer Science 1975 4th Symposium, Mariánské Lázně, September 1–5, 1975
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Each computable function has an infinite number of different program representations in a given
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Rules out assigning to arbitrary functions their computational complexity
395:"A Machine-Independent Theory of the Complexity of Recursive Functions" 32: 62:
computational complexity, meaning the assignment to any
434:(1975). "Ten years of speedup". In BeÄŤvář, Jiří (ed.). 350: 275: 253: 230: 210: 190: 170: 146: 123: 87: 356: 335:{\displaystyle f(x,\Phi _{j}(x))\leq \Phi _{i}(x)} 334: 259: 236: 216: 196: 176: 152: 129: 105: 164:computable function) so that for every program 137:with two parameters, then there exists a total 8: 66:of the complexity of an optimal program for 498:Theorems in computational complexity theory 349: 317: 292: 274: 252: 229: 209: 189: 169: 145: 122: 86: 7: 314: 289: 97: 14: 106:{\displaystyle (\varphi ,\Phi )} 54:(such a program could be called 21:computational complexity theory 329: 323: 307: 304: 298: 279: 100: 88: 1: 514: 31:in 1967, is a fundamental 474:"Blum's Speed-Up Theorem" 444:10.1007/3-540-07389-2_179 204:, there exists a program 378:Gödel's speed-up theorem 35:about the complexity of 80:Blum complexity measure 358: 336: 261: 238: 218: 198: 178: 154: 131: 107: 25:Blum's speedup theorem 416:10.1145/321386.321395 359: 337: 262: 239: 219: 199: 179: 155: 132: 108: 432:Van Emde Boas, Peter 348: 273: 251: 228: 208: 188: 168: 144: 139:computable predicate 121: 117:computable function 85: 44:programming language 37:computable functions 46:. In the theory of 471:Weisstein, Eric W. 403:Journal of the ACM 354: 332: 257: 234: 214: 194: 174: 150: 127: 103: 52:complexity measure 27:, first stated by 453:978-3-540-07389-5 357:{\displaystyle f} 260:{\displaystyle x} 237:{\displaystyle g} 217:{\displaystyle j} 197:{\displaystyle g} 177:{\displaystyle i} 153:{\displaystyle g} 130:{\displaystyle f} 505: 484: 483: 457: 427: 399: 366:speedup function 363: 361: 360: 355: 341: 339: 338: 333: 322: 321: 297: 296: 266: 264: 263: 258: 243: 241: 240: 235: 223: 221: 220: 215: 203: 201: 200: 195: 183: 181: 180: 175: 159: 157: 156: 151: 136: 134: 133: 128: 112: 110: 109: 104: 513: 512: 508: 507: 506: 504: 503: 502: 488: 487: 469: 468: 465: 454: 430: 397: 389: 386: 374: 346: 345: 313: 288: 271: 270: 249: 248: 226: 225: 206: 205: 186: 185: 166: 165: 142: 141: 119: 118: 83: 82: 76: 74:Speedup theorem 17: 12: 11: 5: 511: 509: 501: 500: 490: 489: 486: 485: 464: 463:External links 461: 460: 459: 452: 428: 410:(2): 322–336. 385: 382: 381: 380: 373: 370: 364:is called the 353: 343: 342: 331: 328: 325: 320: 316: 312: 309: 306: 303: 300: 295: 291: 287: 284: 281: 278: 256: 233: 213: 193: 173: 162:boolean valued 149: 126: 102: 99: 96: 93: 90: 75: 72: 15: 13: 10: 9: 6: 4: 3: 2: 510: 499: 496: 495: 493: 481: 480: 475: 472: 467: 466: 462: 455: 449: 445: 441: 437: 433: 429: 425: 421: 417: 413: 409: 405: 404: 396: 392: 388: 387: 383: 379: 376: 375: 371: 369: 367: 351: 326: 318: 310: 301: 293: 285: 282: 276: 269: 268: 267: 254: 247: 231: 211: 191: 171: 163: 147: 140: 124: 116: 94: 91: 81: 73: 71: 69: 65: 61: 57: 53: 49: 45: 40: 38: 34: 30: 26: 22: 477: 435: 407: 401: 391:Blum, Manuel 365: 344: 244:so that for 77: 67: 63: 59: 55: 41: 24: 18: 29:Manuel Blum 384:References 246:almost all 48:algorithms 479:MathWorld 315:Φ 311:≤ 290:Φ 98:Φ 92:φ 492:Category 424:15710280 393:(1967). 372:See also 78:Given a 56:optimal 33:theorem 450:  422:  113:and a 420:S2CID 398:(PDF) 115:total 60:their 448:ISBN 224:for 184:for 440:doi 412:doi 160:(a 19:In 494:: 476:. 446:. 418:. 408:14 406:. 400:. 39:. 23:, 482:. 458:. 456:. 442:: 426:. 414:: 352:f 330:) 327:x 324:( 319:i 308:) 305:) 302:x 299:( 294:j 286:, 283:x 280:( 277:f 255:x 232:g 212:j 192:g 172:i 148:g 125:f 101:) 95:, 89:( 68:f 64:f

Index

computational complexity theory
Manuel Blum
theorem
computable functions
programming language
algorithms
complexity measure
Blum complexity measure
total
computable predicate
boolean valued
almost all
Gödel's speed-up theorem
Blum, Manuel
"A Machine-Independent Theory of the Complexity of Recursive Functions"
Journal of the ACM
doi
10.1145/321386.321395
S2CID
15710280
Van Emde Boas, Peter
doi
10.1007/3-540-07389-2_179
ISBN
978-3-540-07389-5
Weisstein, Eric W.
"Blum's Speed-Up Theorem"
MathWorld
Category
Theorems in computational complexity theory

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