Full Papers in Refereed Journals

  1. C. S. Calude, E. Calude. The complexity of mathematical problems: An overview of results and open problems, International Journal of Unconventional Computing, 9(3-4) (2013), 327-343.
  2. B. Burgin, C. S. Calude, E. Calude. Inductive complexity measures for mathematical problems, International Journal of Foundations of Computer Science 24, 4 (2013) 487-500..
  3. A. Abbott, C. S. Calude, K. Svozil. A quantum random number generator certified by value indefiniteness, Mathematical Structures in Computer Science, 2013, to appear.
  4. C. S. Calude, E. Calude, M. S. Queen. Inductive complexity of the P versus NP problem, Parallel Processing Letters 23, 1 (2013), 1350007-1-1350007-16.
  5. C. S. Calude. The halting problem, Canadian Mathematical Society Notes, 45, 2, March-April (2013), 16-17.
  6. D. H. Bailey, J. M. Borwein, C. S. Calude, M. J. Dinneen, M. Dumitrescu, A. Lee. An empirical approach to the normality of pi, Experimental Mathematics 21, 4 (2012), 375-384.
  7. A. A. Abbott, C.S. Calude, J. Conder, K. Svozil. Strong Kochen-Specker theorem and incomputability of quantum randomness, Physical Review A 86, 6 (2012), DOI: 10.1103/PhysRevA.00.002100.
  8. C. S. Calude, B. S. Cooper. Introduction: computability of the physical, Mathematical Structures in Computer Science 22, 05 (2012), 723-728.
  9. A. Abbott, C. S. Calude. Von Neumann normalisation of a quantum random number generator, Computability, 1 (2012), 59-83.
  10. C. S. Calude, E. Calude, M. S. Queen. The complexity of Euler's integer partition theorem, Theoretical Computer Science 454 (2012), 72-80.
  11. A. A. Abbott, M. Bechmann, C. S. Calude, A. Sebald. A nuclear magnetic resonance implementation of a classical Deutsch-Jozsa algorithm, International Journal of Unconventional Computing 8,2 (2012), 161-175.
  12. A. Abbott, C. S. Calude, K. Svozil. On demons and oracles, Asia Pacific Mathematics Newsletter 2,1 (2012), 9-15.
  13. C. S. Calude, K. Salomaa, T. K. Roblot. State-size hierarchy for FS-complexity, International Journal of Foundations of Computer Science 23, 1 (2012) 37-50.
  14. C. S. Calude, J. P. Lewis. Is there a universal image generator?, Applied Mathematics and Computation 218 (2012), 8151-8159.% doi: 10.1016/j.amc.2011.06.35.
  15. A. Akhtarzada, C. S. Calude, J. Hosking. A multi-criteria metric algorithm for recommender systems, Fundamenta Informaticae 110 (2011), 1-11.
  16. C. S. Calude, K. Salomaa, T. K. Roblot. Finite state complexity, Theoretical Computer Science 412 (2011), 5668-5677.
  17. C. S. Calude, A. Nies, L. Staiger and F. Stephan. Universal recursively enumerable sets of strings, Theoretical Comput. Sci. 412 (2011), 2253-2261.
  18. C. S. Calude, M. Cavaliere, R. Mardare. An observer-based de-quantisation of Deutsch's algorithm, International Journal of Foundations of Computer Science 22, 1 (2011), 191-202.
  19. C. S. Calude, E. Calude and K. Svozil. The complexity of proving chaoticity and the Church-Turing Thesis, Chaos 20 037103 (2010), 1-5.
  20. C. S. Calude, N. J. Hay, F. Stephan. Representation of left-computable epsilon-random reals, Journal of Computer and System Sciences 77 (2011), 812-819.
  21. C. S. Calude, M. J. Dinneen, Monica Dumitrescu, K. Svozil. Experimental evidence of quantum randomness incomputability, Physical Review A, 82, 022102 (2010), 1-8.
  22. C. S. Calude, L. Staiger. A note on accelerated Turing machines, Mathematical Structures in Computer Science, 20 (2010), 1011-1017.
  23. C. S. Calude, Elena Calude. The complexity of the Four Colour Theorem, LMS J. Comput. Math. 13 (2010), 414-425.
  24. C. S. Calude. Simplicity via provability for universal prefix-free Turing machines, Theoretical Comput. Sci., 412 (2010), 178-182. DOI: 10.1016/j.tcs.2010.08.002.
  25. C. S. Calude, Elena Calude. The Complexity of Mathematical Problems. Part 2, Complex Systems 18 (2010), 387-401.
  26. C. S. Calude, G. J. Chaitin. What is ... a halting probability?, Notices of the AMS 57, 2 (2010), 236-237.
  27. C. S. Calude, M. Zimand. Algorithmically independent sequences, Information and Computation 208 (2010), 292-308.
  28. C. S. Calude, Elena Calude. Evaluating the Complexity of Mathematical Problems. Part 1, Complex Systems 18(2009), 267-285.
  29. C. S. Calude, N. J. Hay. Every computably enumerable random real is provably computably enumerable random, Logic Journal of the IGPL , June, 2009, 24 pp, doi:10.1093/jigpal/jzp015.
  30. C.S. Calude, H. Juergensen, L. Staiger. Topology on words, Theoretical Comput. Sci. 410 (2009) 2323-2335.
  31. C.S. Calude and L. Staiger. On universal computably enumerable prefix codes, Mathematical Structures in Computer Science 19 (2009), 45-57.
  32. C. S. Calude, K. Svozil. Quantum randomness and value indefiniteness, Advanced Science Letters 1 (2008), 165-168.
  33. C. S. Calude, M. A. Stay. Most programs stop quickly or never halt, Advances in Applied Mathematics , 40 (2008), 295-308.
  34. C. S. Calude. De-quantising the solution of Deutsch's problem, International Journal of Quantum Information 5, 4(2007), 1-7.
  35. C. S. Calude, M. J. Dinneen. Exact approximations of omega numbers, Int. Journal of Bifurcation & Chaos , 17, 6 (2007), 1937-1954.
  36. C. S. Calude, G. J. Chaitin. A dialogue on mathematics & physics, The Rutherford Journal: The New Zealand Journal for the History and Philosophy of Science and Technology , Vol. 2, 2006-2007.
  37. C. S. Calude, M. A. Stay. Natural halting probabilities, partial randomness, and Zeta functions, Information and Computation 204 (2006), 1718-1739.
  38. C. S. Calude, Elena Calude, M. J. Dinneen. A new measure of the difficulty of problems, Journal for Multiple-Valued Logic and Soft Computing 12 (2006), 285-307.
  39. C. S. Calude, C. Campeanu, Monica Dumitrescu. Automata recognizing no words: A statistical approach, Fundamenta Informaticae 72 (2006), 1-18.
  40. C. S. Calude, L. Staiger, S. A. Terwijn. On partial randomness, Annals of Applied and Pure Logic, 138 (2006), 20-30.
  41. C. S. Calude, M. A. Stay. From Heisenberg to Goedel via Chaitin, International Journal of Theoretical Physics 44, 7 (2005), 1053-1065.
  42. C.S. Calude, H. Juergensen. Is Complexity a Source of Incompleteness?, Advances in Applied Mathematics, 35 (2005), 1-15.
  43. C. S. Calude, L. Staiger, K. Svozil. Randomness Relative to Cantor Expansions, Comm. Nonlinear Science Numerical Simulation, 10/8 (2005), 921-930.
  44. C. S. Calude, S. Rudeanu. Proving as a computable procedure, Fundamenta Informaticae, 64 (2005), 1-10.
  45. C. S. Calude, L. Staiger. Generalisations of disjunctive sequences, style="font-style: italic;"> Math. Log. Quart., 51, 2 (2005), 120-128.
  46. C.S. Calude, Elena Calude, S. Marcus. Passages of proof, Bull. Eur. Assoc. Theor. Comput. Sci. EATCS 84 (2004), 167-188.
  47. C. S. Calude, J. L. Casti. The jumble cruncher, The New Scientist 25 September 2004, 36-37: page 36, page 37. Posted also by ID Quantique.
  48. New Scientist








  49. C. S. Calude, G. Paun. Bio-steps beyond Turing , BioSystems 77 (2004), 175-194.
  50. J. J. Arulanandham, C. S. Calude, M. J. Dinneen. A fast natural algorithm for searching, Theoret. Comput Sci., Natural Computing, 320, 1 (2004), 3-13. Among TCS most requested articles Jan-Aug 2004.
  51. C.S. Calude, Elena Calude, M.J. Dinneen. What is the value of Taxicab(6)? , J. UCS 9, 10 (2003), 1196-1203.
  52. C.S. Calude, S. Marcus, L. Staiger. A topological characterization of random sequences,  Inform. Process. Lett. 88 (2003), 245-250.
  53. J. J. Arulanandham,  C.S. Calude,  M.J. Dinneen. Solving SAT with bilateral computing,  Romanian Journal of Information Science and Technology 6, 1-2 (2003), 9-18.
  54. C. S. Calude, B. Pavlov. Coins, quantum measurements, and Turing's barrier, Quantum Information Processing 1, 1-2 (2002), 107-127.

  55. C. S. Calude. Incompleteness, complexity, randomness and beyond, Journal for Artificial Intelligence, Philosophy and Cognitive Science, 12, 4 (2002), 503-517.  

  56. C. S. Calude, M. J. Dinneen and C.-K. Shu. Computing a glimpse of randomness, Experimental Mathematics ,  2 (2002), 369-378. Slides

  57. C. S. Calude, K. Salomaa, S. Yu. Additive distance and quasi-distances between words, J. UCS 8, 2 (2002), 141-152.

  58. J. J. Arulanandham, C. S. Calude, M. J. Dinneen. Bead-Sort: A natural sorting algorithm, EATCS Bull. 76 (2002), 76 (2002), 153-162. Simulation of the Bead-Sort Algorithm with just one line MGS code

  59. C. S. Calude, Monica Dumitrescu. Entropic measures, Markov information sources and complexity, Appl. Math. Comput. 132, 2-3 (2002), 369-384.

  60. C. S. Calude. Chaitin Omega numbers, Solovay machines and incompleteness, Theoret. Comput. Sci. 284 (2002), 269-277. Top 25 of most downloaded TCS articles for April-August 2002. 

  61. C. S. Calude. A characterization of c.e. random reals, Theoret. Comput. Sci. , 217 (2002), 3-14. 

  62. C. S. Calude, H. Ishihara, T. Yamaguchi. Minimal programs are almost optimal, International Journal of Foundations of Computer Science 12, 4 (2001), 479-489.

  63. C. S. Calude. Real numbers: from computable to random, Studia Universitatis Babes-Bolyai, Philosophia, XLVI, 1-2 (2001), 3-24.

  64. C. S. Calude, P. Hertling, B. Khoussainov, Y. Wang. Recursively enumerable reals and Chaitin Omega numbers, Theoret. Comput. Sci. , 255 (2001), 125-149.

  65. C. S. Calude, P. Hertling, H. Jürgensen, K. Weihrauch. Randomness on full shift spaces, Chaos, Solitons & Fractals , 12/3 (2001), 491-503.

  66. C. S. Calude, G. Paun, Monica Tatarâm. A glimpse into natural computing, J. Multi Valued Logic , 7 (2001), 1-28.

  67. C. S. Calude, Elena Calude, Terry Chiu, Monica Dumitrescu, R.  Nicolescu. Testing computational complementarity for Mermin automata, J. Multi Valued Logic , 6 (2001), 47-65.

  68. C. S. Calude, P. Hertling, H. Jürgensen, K. Weihrauch. Randomness on full shift spaces, Chaos, Solitons & Fractals , 12/3 (2001), 491-503.

  69. C. S. Calude, M. J. Dinneen, K. Svozil. Reflections on quantum computing, Complexity , 6, 1 (2000), 35-37.

  70. C. S. Calude, G. Paun. Computing with cells and atoms in a nutshell, Complexity , 6, 1 (2000), 38-48.

  71. C. S. Calude, Elena Calude, B. Khoussainov. Finite nondeterministic automata: Simulation and minimality, Theoret. Comput. Sci. 242, 1-2 (2000), 219-235.

  72. C. S. Calude, Marjo Lipponen. Computational complementarity and shift spaces, Chaos, Solitons & Fractals 11 (2000), 315-319.

  73. C. S. Calude, G. J. Chaitin. Randomness everywhere, Nature , 400, 22 July (1999), 319-320.

  74. C. S. Calude, F. W. Meyerstein. Is the universe lawful ?, Chaos, Solitons & Fractals 10, 6 (1999), 1075-1084.

  75. C. S. Calude, P. H. Hertling, K. Svozil. Embedding quantum universes into classical ones, Foundations of Physics , 29, 3 (1999), 349-379.

  76. D. Bridges, C. Calude, B. Pavlov, D. Stefanescu. The inverse function theorem-a constructive approach, Chaos, Solitons & Fractals 10, 6 (1999), 927-934.

  77. C. Calude, S. Marcus, D. Stefanescu. The Creator versus its creation. From Scotus to Gödel, Collegium Logicum. Annals of the Kurt-Gödel-Society , Vol. 3, Institute of Computer Science, AS CR Prague, Vienna, 1999, 1-10.

  78. C. S. Calude, T. Zamfirescu. Most numbers obey no probability laws, Publicationes Mathematicae Debrecen, Tome 54 Supplement (1999), 619-623.

  79. C. S. Calude, J. L. Casti. Silicon, molecules, or photons ? Complexity 4, 1, (1998), 13.

  80. C. S. Calude, Elena Calude, Catalina Stefanescu. Computational complementarity for Mealy automata, EATCS Bull. 66 (1998), 139-149.

  81. C. S. Calude, P. Hertling. Computable approximations of reals: An information-theoretic analysis, Fundamenta Informaticae  33 (1998), 1-16.

  82. C. S. Calude, J. L. Casti. Parallel thinking, Nature 392, 9 April (1998), 549-551.

  83. C. S. Calude, J. L. Casti, P. B. Gibbons, Marjo Lipponen. Unconventional models of computation: A conventional report, Complexity 3, 4 (1998), 8-11.

  84. C. S. Calude, P. H. Hertling, K. Svozil. Kochen-Specker theorem: Two geometric proofs, Tatra Mt. Math. Publ. 15 (1998), 133-142.

  85. C. Calude, T. Zamfirescu. The typical number is a lexicon, New Zealand Journal Math. 27 (1998), 7-13.

  86. C. S. Calude. A genius's story: Two books on Gödel. The life and works of a master logician, Complexity 3, 2 (1997), 1-5.

  87. C. S. Calude, A. Nies. Chaitin Omega numbers and strong reducibilities, J. UCS 3 (1997), 1161-1166.

  88. C. S. Calude, I. Tomescu. Optimum extendible prefix codes, J. UCS 3 (1997), 1167-1179.

  89. C. Calude, Elena Calude, B. Khoussainov. Deterministic automata: simulation, universality and minimality, Annals of Applied and Pure Logic 90, 1-3 (1997), 263-276.

  90. C. Calude, P. Hertling, B. Khoussainov. Do the zeros of Riemann's zeta-function form a random sequence ? EATCS Bull. 62 (1997), 199-207.

  91. C. Calude, Elena Calude, K. Svozil, S. Yu. Physical versus computational complementarity I, International Journal of Theoretical Physics 36 (1997), 1495-1523.

  92. C. Calude, S. Yu. Language-theoretic complexity of disjunctive sequences, Discrete Appl. Mathematics 80 (1997), 199-205.

  93. C. Calude. The finite, the unbounded and the infinite, J. UCS 2 (1996), 242-244.

  94. C. Calude, C. Grozea. Kraft-Chaitin inequality revisited, J. UCS 2 (1996), 306-310.

  95. C. Calude. Algorithmic information theory: Open problems, J. UCS 2 (1996), 439-441.

  96. C. Calude, C. Câmpeanu. Are binary codings universal ?, Complexity 1, 15 (1996), 47-50.

  97. C. Calude, M. Zimand. Effective category and measure in abstract complexity theory, Theoret. Comput. Sci. 154 (1996), 307-327.

  98. A. Arslanov, C. Calude. Program-size complexity computes the halting problem, EATCS Bull. 57 (1995), 199-200. [Another solution by G. J. Chaitin]

  99. C. Calude. What is a random string ? J. UCS , Vol. 1,1 (1995), 48-66.

  100. C. Calude, Monica Tataram. Three theories of computational complexity. Extended abstract, An. Univ. Iasi, Inf. 3 (1994), 45-52.

  101. C. Calude, H. Jürgensen, M. Zimand. Is independence an exception ?, Appl. Math. Comput. 66 (1994), 63-76.

  102. D. S. Bridges, C. Calude. On recursive bounds for the exceptional values in speed-up, Theoret. Comput. Sci. 132 (1994), 387-394.

  103. C. Calude, C. Câmpeanu. Note on the topological structure of random strings, Theoret. Comput. Sci. 112 (1993), 383-390.

  104. C. Calude, G. Istrate, M. Zimand. Recursive Baire classification and speedable functions, Z. Math. Logik Grundlang. Math. 3 (1992), 169-178.

  105. C. Calude. Algorithmic complexity: A topological point of view, Singularité 2, 10 (1991), 28-29. [With a comment and a list of open problems due to the editor] (in French)

  106. C. Calude. Relativized topological size of sets of partial recursive functions, Theoret. Comput. Sci. 87 (1991), 347-352.

  107. C. Calude, G. Istrate. Determining and stationary sets for some classes of partial recursive functions, Theoret. Comput. Sci. 82 (1991), 151-155.

  108. C. Calude, Lila Sântean. On a theorem of Günter Asser, Z. Math. Logik Grundlang. Math. 36 (1990), 143-147. [With a comment by G. Asser]

  109. C. Calude, Eva Kurta. On Kraft-Chaitin inequality, Rev. Roumaine Math. Pures Appl. 35 (1990), 597-604.

  110. C. Calude, I. Chitescu. Qualitative properties of P. Martin-Löf random sequences, Boll. Unione Mat. Ital. VII, Ser. B3, 240 (1989), 229-240.

  111. C. Calude, I. Chitescu. Upper limitation of Kolmogorov complexity and universal P. Martin-Löf tests, Journal of Computational Mathematics 1 (1989), 61-70.

  112. C. Calude, S. Marcus. Sudan's recursive and non-primitive recursive function: a retrospective look, An. Univ. Bucuresti, Mat.-Inf. 2 (1989), 25-30.

  113. C. Calude, I. Chitescu. Random sequences: some topological and measure-theoretical properties, An. Univ. Bucuresti, Mat.-Inf. 2 (1988), 27-32.

  114. C. Calude, I. Chitescu. Random sequences according to P. Martin-Löf, Found. Control Engrg. 12, 3 (1987), 75-84.

  115. C. Calude. Super-exponentials non-primitive recursive, but rudimentary, Inform. Process. Lett. 25 (1987), 311-315.

  116. C. Calude. Note on Ehrenfeucht's conjecture and Hilbert's basis theorem, EATCS Bull. 29 (1986), 18-22.

  117. S. Buzeteanu, C. Calude. Functions having the graph in the n -th Grzegorczyk class, Found. Control Engrg. 11 (1986), 61-67.

  118. C. Calude, I. Chitescu, L. Staiger. P. Martin-Löf tests: representability and embeddability, Rev. Roumaine Math. Pures Appl. 30 (1985), 719-732.

  119. C. Calude, I. Chitescu. A combinatorial characterization of sequential P. Martin-Löf tests, Internat. J. Comput. Math. 17 (1985), 53-64.

  120. C. Calude, M. Zimand. A relation between correctness and randomness in the computation of probabilistic algorithms, Internat. J. Comput. Math. 16 (1984), 47-53.

  121. C. Calude, I. Chitescu. A class of universal P. Martin-Löf tests, EACTS Bull. 23 (1984), 15-22.

  122. C. Calude, I. Chitescu. Representability of recursive P. Martin-Löf tests, Kybernetika (Prague) 19 (1983), 526-536.

  123. C. Calude. A simple non-uniform operation, EATCS Bull. 20 (1983), 40-46.

  124. C. Calude, Elena Calude. On some discrete metrics, Bull. Math. Soc. Sci. Math. R. S. Roumanie (N. S.) 27 (75) (1983), 213-216.

  125. C. Calude, Gh. Paun. Independent instances for some undecidable problems, RAIRO Inform. Theor. 17 (1983), 49-54.

  126. C. Calude. On a class of independent problems related to Rice theorem, ACM SIGACT News 15 (1983), 53-57.

  127. C. Calude, Monica Tataram. Universal sequences of primitive recursive functions, Rev. Roumaine Math. Pures Appl. 28 (1983), 381-389.

  128. C. Calude, I. Chitescu. On representability of P. Martin-Löf tests, Kybernetika (Prague) 19 (1983), 42-47.

  129. C. Calude. Topological size of sets of partial recursive functions, Z. Math. Logik Grundlang. Math. 28 (1982), 455-462.

  130. C. Calude, I. Chitescu. On Per Martin-Löf random sequences, Bull. Math. Soc. Sci. Math. R. S. Roumanie (N.S.) 26 (74) (1982), 217-221.

  131. C. Calude, I. Chitescu. Random strings according to A. N. Kolmogorov and P. Martin-Löf. Classical approach, Found. Control Engrg. 7 (1982), 73-85.

  132. C. Calude, I. Chitescu. Strong noncomputability of random strings, Internat. J. Comput. Math. 11 (1982), 43-45.

  133. C. Calude. Note on a hierarchy of primitive recursive functions, Rev. Roumaine Math. Pures Appl. 27 (1982), 935-936.

  134. C. Calude, Elena Calude. A metrical method for multicriteria decision making, St. Cerc. Mat. 34 (1982), 223-234. (in Romanian)

  135. C. Calude, Gh. Paun. On the adequacy of a grammatical model of the brain,  Rev. Roumaine Ling. 27 (1982), 343-351. (Romanian Contributions to the XIII-th International Congress of Linguistics, Tokyo, 1982, Section Linguistics and the Computer)

  136. M. Andrasiu, C. Calude, Gh. Paun. Possibilities of multicriteria decision making, St. Cerc. Mat. 34 (1982), 87-103. (in Romanian)

  137. C. Calude, V. Vieru. An iterative normal form for the partial recursive functions, Found. Control Engrg. 6 (1981), 133-144.

  138. C. Calude, Gh. Paun. Global syntax and semantics for recursively enumerable languages, Fund. Inform. 4 (1981), 245-254.

  139. C. Calude. Darboux property and primitive recursive functions, Rev. Roumaine Math. Pures Appl. 26 (1981), 1187-1192.

  140. C. Calude, V. Vieru. A note on Knuth's iterated powers, An. Stiin. Univ. ``Alex.I.Cuza'', Iasi, Sect. I Mat. 27 (1981), 253-255.

  141. C. Calude, Elena Calude. On the ``rationality'' of Onicescu's method for multicriteria making, Rev. de Statistica 30 (1981), 58-60. (in Romanian)

  142. C. Calude, S. Marcus. Man-computer communication, Rev. Roumaine Ling. 26 (1981), 103-112.

  143. C. Calude, Gh. Paun. The absence of contextual ambiguities in programming languages, Rev. Roumaine Ling. Cahiers Ling. Theor. Appl. 18 (1981), 91-110.

  144. M. Andrasiu, C. Calude, Gh. Paun. Some extensions of the multicriteria decision problem, Rev. de Statistica 29 (1980), 43-49. (in Romanian)

  145. C. Calude, S. Marcus, I. Tevy. Recursive properties of Sudan function, Rev. Roumaine Math. Pures Appl. 25 (1980), 503-507.

  146. C. Calude, S. Marcus, I. Tevy. The first example of a recursive function which is not primitive recursive, Historia Math. 9 (1979), 380-384.

  147. C. Calude, V. E. Cazanescu. On topologies generated by Moisil resemblance relations, Discrete Math. 25 (1979), 109-115.

  148. C. Calude, S. Marcus, Gh. Paun. The universal grammar as a hypothetical brain, Rev. Roumaine Ling. 27 (1979), 479-489.

  149. C. Calude. Categorical methods in computability theory II, St. Cerc. Mat. 30 (1978), 361-383. (in Romanian)

  150. C. Calude. Categorical methods in computability theory I, St. Cerc. Mat. 30 (1978), 253-277. (in Romanian)

  151. C. Calude, Brândusa Fântâneanu. On recursive, non-primitive recursive functions, Bull. Math. Soc. Sci. Math. R. S. Roumanie 22 (1978), 255-258.

  152. C. Calude. On the category of recursive languages, Mathematica (Cluj) 19 (42), (1978), 29-32.

  153. C. Calude. A grammatical construction of Gödel numberings, C. R. Acad. Sci. Paris Ser. I Math. 284 (1977), 525-526. (in French)

  154. C. Calude. On the compatibility between the analytic and generative hierarchies of formal languages, Rev. Roumaine Math. Pures Appl. 22 (1977), 437-439.

  155. C. Calude. On some topological properties of semilattice ordered semigroups, Bull. Math. Soc. Sci. Math. R. S. Roumanie 19 (1976), 3-10.

  156. C. Calude. An axiomatics for a deontic logic with an infinity of truth values, Rev. Roumaine Math. Pures Appl. 21 (1976), 267-273. (in French)

  157. C. Calude. On the metrizability of a free monoid, Discrete Math. 16, 19 (1976), 307-310.

  158. C. Calude. On contextual distances in mathematical linguistics, St. Cerc. Mat. 28 (1976), 31-35. (in Romanian)

  159. C. Calude. Some arguments against the formal character of programming languages, Rev. Roumaine Ling.-Cahiers Ling. Theor. Appl. 13 (1976), 257-264. (in French)

  160. C. Calude, S. Marcus, I. Tevy. On recursive functions which are not recursive primitive, Rev. Roumaine Sci. Soc., Sér. Phil.-Logique 19 (1975), 185-188. (in French)

  161. C. Calude. A statistical experiment in Assembler 360, Cahiers Ling. Theor. Appl. 11 (1974), 219-230. (in French)

  162. C. Calude. On a class of distances in a free semigroup, Bull. Math. Soc. Sci. Math. R. S. Roumanie 17 (65) (1973), 133-143. (in French)

  163. C. Calude. On some morphological aspects of the language Assembler 360, Cahiers Ling. Theor. Appl. 10 (1973), 153-162. (in French)

Papers in Refereed Conference Proceedings

  1. C. S. Calude, K. Tadaki. Spectral representation of some computably enumerable sets with an application to quantum provability, in G. Mauri et al. (eds.). Proceedings of UCNC 2013, LNCS 7956, Springer, 2013, 43-54.

  2. A. Akhtarzada, C. S. Calude, J. Hosking. Metric based recommender systems, in M. Deza, M. Petitjean, K. Markov (eds.). Mathematics of Distances and Applications, ITHEA, Sofia, 2012, 103-117.

  3. C. S. Calude, E. Calude, M. S. Queen. Inductive complexity of P versus NP problem. Extended abstract, in J. Durand-Lose, N. Jonoska (eds.). Proceedings UCNC 2012, LNCS 7445, Springer, 2012, 2-9.

  4. A. A. Abbott, C. S. Calude. Von Neumann normalisation and symptoms of randomness: An application to sequences of quantum random bits, in C. S. Calude, J. Kari, I. Petre, G. Rozenberg (eds.). Proc. 10th International Conference Unconventional Computation, Lecture Notes Comput. Sci. 6714, Springer, Heidelberg, 2011, 40-51.

  5. C. S. Calude, M. J. Dinneen, M. Dumitrescu, K. Svozil. Experimental evidence of quantum randomness incomputability, in H. Guerra (ed.). Physics and Computation 2010, Pre-Proceedings, CAMIT, University of Azores, 2010, 127-145.

  6. C. S. Calude, K. Salomaa, T. K. Roblot. Finite-state complexity and the size of transducers, in I. McQuillan and G. Pighizzini (eds.). 12th International Workshop on Descriptional Complexity of Formal Systems (DCFS 2010), EPTCS 26, 2010, pp. 38-47.

  7. C. S. Calude, K. Salomaa, T. K. Roblot. Finite-state complexity and randomness, in F. Ferreira, H. Guerra, E. Majordomo, J. Rasga (eds). Programs, Proofs, Processes, 6th Conference on Computability in Europe, CiE 2010, Abstract and Handbook Booklet, Ponta Delgada, Azores, Portugal, University of Azores, 2010, 73-82.

  8. A. A. Abbott, C. S. Calude. Understanding the quantum computational speed-up via de-quantisation, in S. B. Cooper, E. Kashefi, P. Panangaden (eds.). Developments in Computational Models (DCM 2010) EPTCS 26, 2010, pp. 1-12.

  9. C. S. Calude, C. Mueller. Formal proof: reconciling correctness and understanding, in L. Dixon et al. (eds.). Proceedings Calculemus/MKM 2009, LNAI 5625, Springer, 2009, 217-232.

  10. C. S. Calude. Simplicity via provability for universal prefix-free Turing machines, in T. Neary, D. Woods, A. K. Seda and N. Murphy (eds.). The Complexity of Simple Programs 2008, EPTCS 1, 2009, pp. 16-21. (preliminary version in T. Neary, D. Woods, A. Seda, N. Murphy (eds.). Proc. International Workshop on The Complexity of Simple Programs, Cork, Ireland, 2008, 15-22.) (invited).

  11. C. S. Calude. Information: the algorithmic paradigm, in G. Sommaruga (ed.) Formal Theories of Information, Lecture Notes Comput. Sci. 5363, Springer (2009), 79-94. (invited)

  12. C. S. Calude. Can Peano Arithmetic Prove Randomness?, in M. Ito (ed.). Workshop on Automata, Formal Languages and Algebraic Systems, Kyoto, September 2008, 5pp. (invited).

  13. C. S. Calude, A. Nies, L. Staiger and F. Stephan. Universal recursively enumerable sets of strings, in M. Ito, M. Toyama (eds.). Developments in Language Theory (DLT'08), Lectures Notes in Comput. Sci. 5257, Springer-Verlag, Berlin, 2008, 170-182.

  14. C. S. Calude. Incompleteness and complexity, in C. Campeanu, G. Pighizzini (eds.). Proceedings of the International Workshop DCFS'08, UPEI, Charlottetown, Canada, 14-24. (invited)

  15. C. S. Calude, M. J. Dinneen. Is quantum randomness algorithmic random? A preliminary attack, in S. Bozapalidis, A. Kalampakas, G. Rahonis (eds.). Proceedings 1st International Conference on Algebraic Informatics, Aristotle University of Thessaloniki, October, 2005, 195-196. (invited)

  16. C. S. Calude. Algorithmic randomness, quantum physics, and incompleteness, in M. Margenstern (ed.). Proceedings of the Conference "Machines, Computations and Universality" (MCU'2004), Lectures Notes in Comput. Sci. 3354, Springer, Berlin, 2005, 1-17. (invited)

  17. C. S. Calude. Dialogues on quantum computing, in C. Martin-Vide, V. Mitrana and G. Paun (eds.). Formal Languages and Applications, Physica-Verlag, Heidelberg, 2004, 493-506.

  18. C. S. Calude. Who is afraid of randomness?, in E. von Collani (ed.). "Defining the Science of Stochastics", Heldermann Verlag, Sigma Series in Stochastics 1, 2004, 95-116. (Pre-proceedings: in E. von Collani (ed.). Millennial Symposium 'Defining the Science of Stochastics', Wuerzburg University, 2000, 99-122) (invited)

  19. C. S. Calude, E. Calude. Automata: from uncertainty to quantum, in W. Kuich, G. Rozenberg, A. Salomaa (eds.) Developments in Language Theory (DLT'01), Lectures Notes in Comput. Sci. 2295, Springer-Verlag, Berlin, 2002, 1-14. Preproceedings published by the Institute fur Algebra un Computermathematik, Technische Universtat Wien, Austria, 2001, 1-16.

  20. C. S. Calude, K. Salomaa, S. Yu. Metric lexical analysis, in O.~Boldt, H. Jurgensen (eds.) Automata Implementation, Lectures Notes in Computer Science 2214, Springer-Verlag, Heidelberg, 2001, 48-59. Prepublication in O.~Boldt, H.~Jurgensen, L. Robbins (eds.). Workshop on Implementing Automata'99 (WIA'99), Preproc., 17-19 July, 1999, Potsdam, Universtitat Potsdam, Institut fur Informatik, Germany, 1999, VI-1-12.

  21. C. S. Calude, E. Calude, P. Kay. Liars, demons and chaos, in M. Ito, G. Paun, S. Yu (eds.). Words, Semigroups, and Transductions, World Scientific, Singapore, 2001, 33-46.

  22. C. S. Calude. A glimpse into algorithmic information theory, in L. Cavedon, P. Blackburn, N. Braisby, A. Shimojima (eds.). Logic, Language and Computation, Vol. 3, CSLI Series, CSLI Lectures Notes 111, Stanford, 2000, 67-83.

  23. C. S. Calude, E. Calude. Bisimulations and behaviour of nondeterministic automata, in G. Rozenberg, W. Thomas (eds.). Developments in Language Theory. Foundations, Applications, and Perspectives, World Scientific, Singapore, 2000, 60-70. Prepublication in W. Thomas (ed.). DLT'99, Developments in Language Theory, Fourth International Conference, Preproc., 6-9 July, 1999 Aachen, Germany, Aachener Informatik-Berichte 99-5, 129-139.

  24. C. S. Calude. A characterization of c.e.~random reals, in J.~Dassow, D.~Wotschke (eds.) . International Workshop on Descriptional Complexity of Automata, Grammars and Related Structures (DCAGRS'99), Preproc., 20-23 July, Magdeburg, Germany, 1999, 89-98.

  25. C. S. Calude, E. Calude, K. Svozil. Quantum correlations conundrum: an automaton-theoretic approach, in C. Martin-Vide, Gh. Paun (eds.). Recent Topics in Mathematical and Computational Linguistics, The Publishing House of the Romanian Academy, Bucharest, 2000, 55-67. Prepublication in O.~Boldt, H. J. urgensen, L.~Robbins (eds.). Workshop on Implementing Automata'99 (WIA'99), Preproc., 17-19 July, 1999, Potsdam, Universtitat Potsdam, Institut fur Informatik, Germany, VII-1-12.

  26. C. S. Calude, P. H. Hertling. Computable approximations of reals: an information-theoretic analysis, Extended abstract, Third International Conference on Information-Theoretic Approaches to Logic, Language, and Computation, Hsi-tou, Taiwan, The Centre for Research in Cognitive Science & Department of Psychology, National Chung Cheng University, Chiayi, 1998, 29-38.

  27. C. S. Calude, M. Lipponen. Computational complementarity and sofic shifts, in X. Lin (ed.). Theory of Computing 98, Proceedings of the 4th Australasian Theory Symposium, CATS'98, Springer-Verlag, Singapore, 1998, 277-290.

  28. C. S. Calude, P. Hertling, B. Khoussainov, Y. Wang. Recursively enumerable reals and Chaitin $\Omega $ numbers, in M.~Morvan, C.~Meinel, D.~Krob (eds.). STACS'98, Proceedings of the 15th Annual Symposium on Theoretical Aspects of Computer Science, Paris, 1998, Lecture Notes Comput. Sci. 1373, Springer-Verlag, Berlin, 1998, 596-606.

  29. C. Calude, E. Calude, B. Khoussainov. Deterministic automata: simulation, universality and minimality, Extended abstract, in S. Bozapalidis (ed.). Proceedings of the 3rd International Conference Developments in Language Theory, Aristotel University of Thessaloniki, Thessaloniki, Greece, 1997, 519-520.

  30. C. Calude, H. Maurer, A. Salomaa. The Journal of Universal Computer Science and its applications to teaching, in G. Kadunz, H. Kautschitsch, G. Ossinmitz, E. Schneider (eds.). Trends und Perspectiven, Beitrage Zum 7. Internationalen Symposium Zur Didaktik der Mathematik, Klagenfurt, 26-30 September 1994, Verlag Holder-Pichler-Tempsky, Vienna, 1996, 255-261. (invited)

  31. C. Calude, S. Yu. Language-theoretic complexity of disjunctive sequences, in M. E. Houle, P. Eades (eds.). Proceedings CATS'96 (Computing: the Australian Theory Seminar), Melbourne, Australia, 29-39 January 1996, 175-179.

  32. C. Calude, M. Zimand. Effective category and measure in abstract complexity theory: extended abstract, Proceedings FCT'95, Lecture Notes Comput. Sci. 965, Springer-Verlag, Berlin, 1995, 156-171.

  33. C. Calude, H. Jurgensen. Randomness and coding, in M.~Marinov, D. Ivanchev (eds.). 20th Summer School ``Applications of Mathematics in Engineering, Proceedings, Varna, Bulgaria, 1994, Technical University of Sofia, 1995, 53-57.

  34. C. Calude. What is a random string? (extended abstract), in W. Depauli-Schimanovich, E. Koehler, F. Stadler (eds.). The Foundational Debate, Complexity and Constructivity in Mathematics and Physics, Kluwer, Dordrecht, 1995, 101-113. (invited)

  35. C. Calude, D. I. Campbell, K. Svozil, D. Stefanescu. Strong determinism vs. computability, in W. Depauli-Schimanovich, E. Koehler, F. Stadler (eds.). The Foundational Debate, Complexity and Constructivity in Mathematics and Physics, Kluwer, Dordrecht, 1995, 115-131.

  36. C. Calude, H. Jurgensen. Randomness as an invariant for number representations, in H. Maurer, J. Karhumaki, G. Rozenberg (eds.). Results and Trends in Theoretical Computer Science, Springer-Verlag, Berlin, 1994, 44-66. (invited)

  37. C. Calude, A. Salomaa. Algorithmically coding the universe, in G. Rozenberg, A. Salomaa (eds.). Developments in Language Theory, World Scientific, Singapore, 1994, 472-492.

  38. C. Calude. Borel normality and algorithmic randomness, in G. Rozenberg, A. Salomaa (eds.). Developments in Language Theory, World Scientific, Singapore, 1994, 113-129. (invited)

  39. C. Calude. On B. Russell definition of mathematics, Proc. National Symposium Info-Iasi'89, 52-59. (in Romanian) (invited)

  40. C. Calude, D. Vaida. Ehrenfeucht test set theorem and Hilbert basis theorem: a constructive glimpse, in A. Kreczmar, G. Mirkowska (eds.). Proc. Symposium Math. Found. Computer Sci. 1989, Lecture Notes Comput. Sci. 379, Springer-Verlag, Berlin, 1989, 177-184.

  41. C. Calude, D. Vaida. Languages, effectivity and constructive mathematics, Proc. Second National Colloquium on Languages, Logic and Mathematical Linguistics, Brasov, 1988, 47-57.

  42. C. Calude. Romanian results in recursive function theory: 1927-1987, Proc. Computer Center Anniversary Symposium, Bucharest University, 1987, 16-22. (in Romanian) (invited)

  43. C. Calude, D. Vaida. Ehrenfeucht's property and constructivity, Proc. National Symposium Info-Iasi'87, 1-16. (in Romanian) (invited)

  44. C. Calude, I. Chitescu, L. Staiger. P. Martin-L\of tests: representability and embeddability, Proc. National Symposium Info-Iasi'85, Vol. I, 80-88. (in Romanian) (invited)

  45. C. Calude. Dilemmas of computational complexity, in C. Iacob (ed.). Mathematics, Today and Tomorrow, Ed. Academiei, Bucharest, 1985, 63-73. (in Romanian) (invited)

  46. C. Calude, I. Chitescu. On a (too) general theory of random sequences, in M. G. Demetrescu, M. Iosifescu (eds.). Studies in Probability Theory and Related Topics, Papers in Honour of Octav Onicescu on His 90th Birthday, Nagard Publisher, 1983, 65-69. (invited)

  47. C. Calude. On a class of independent problems related to Rice's theorem, Proc. National Symposium Info-Iasi'83, 29-32. (in Romanian)

  48. C. Calude, I. Chitescu. On Per Martin-Lof random sequences, Proc. National Symposium Info-Iasi'81, 1-5. (in Romanian)

  49. C. Calude, V. Vieru. Knuth test on compiler efficiency, Proc. 4th International Conference on Control Systems and Computer Science, Bucharest, Politechnical Institute, Vol. IV, 1981, 113-115.

  50. C. Calude, Gh. Paun. An argument for the formal character of the programming language Fortran, in P. Miclau, S. Marcus (eds.). Semiotique Roumaine, Bucharest University, 1981, 61-72.

  51. C. Calude, M. Malita, On the category of Cech topological spaces, in A. Czaszar (ed.). Topology, Vol. I, North-Holland, Amsterdam, l980, 225-232.

  52. C. Calude, S. Marcus, Gh. Paun. The universal grammar as a hypothetical brain, Proc. Intern. Symposium on Mathematics in System Theory, Brasov, 1978, 93-114.

  53. C. Calude. Pompeiu's distance between closed sets, Symposium on Geometry and Global Analysis, Bucharest, 1973, Ed. Academiei, Bucharest, 281-288. (in Romanian)

  54. C. Calude. Semiotic analysis of a morphological experiment in a programming language, in S. Chatman, U. Eco, J. M. Klinkenberg (eds.). Approaches to Semiotics, Proc. of the First Congress IAS, 1973, Mouton, The Hague, 1979, 433-436. (in French)

Papers in Refereed Collective Books

  1. C. S. Calude. Afterword: Is all computation?, in H. Zenil (ed.). Irreducibility & Computational Equivalence. Ten Years After Wolframâ A New Kind of Science, Springer, 2013, 475-480.

  2. C. S. Calude, K. Svozil. Is feasibility in physics limited by fantasy alone? in H. Zenil (ed.). A Computable Universe: Understanding Computation & Exploring Nature as Computation, World Scientific, Singapore, 2012, 525-537.

  3. C. S. Calude, W. Meyerstein, A. Salomaa. The Universe is lawless or 'Panton chrematon metron anthropon einai', in H. Zenil (ed.). A Computable Universe: Understanding Computation & Exploring Nature as Computation, World Scientific, Singapore, 2012, 539-547.

  4. C. S. Calude, L. Staiger, M. Stay, Halting and non-halting Turing computations, in S. B. Cooper, J. van Leeuwen (eds.). Alan Turing, His Work and Impact, Elsevier, Amsterdam, 2013, to appear.

  5. A. A. Abbott, C. S. Calude, K. Svozil. A quantum random oracle, in S. B. Cooper, J. van Leeuwen (eds.). Alan Turing, His Work and Impact, Elsevier, Amsterdam, 2013, to appear.

  6. C. S. Calude. Randomness everywhere: My path to algorithmic information theory, in H. Zenil (ed.). Randomness Through Computation, World Scientific, Singapore, 2011, 179-189.

  7. C. S. Calude, J. L. Casti, G. J. Chaitin, P. C. W. Davies, K. Svozil, S. Wolfram. Is the universe random? in H. Zenil (ed.). Randomness Through Computation, World Scientific, Singapore, 2011, 309-350.

  8. C. S. Calude, G. J. Chaitin, E. Fredkin, A. T. Legget, R. de Ruyter, T. Toffoli, S. Wolfram. What Is Computation? (How) Does nature compute? in H. Zenil (ed.). Randomness Through Computation, World Scientific, Singapore, 2011, 351-403. Also in H.~Zenil (ed.). A Computable Universe: Understanding Computation & Exploring Nature as Computation, World Scientific, Singapore, 2012, 673-725.

  9. C. S. Calude, M. J. Dinneen, A. M. Gardner. Opening the book of randomness, in R. Copeland (ed.). DIASPAR. A Mapping of Randomness, 2010.

  10. C. S. Calude, E. Calude, S. Marcus. Proving and programming, in C. S. Calude (ed.). Randomness & Complexity, from Leibniz to Chaitin, World Scientific, Singapore, 2007, 310-321.

  11. V.A. Adamyan, C.~S. Calude, B.S. Pavlov. Transcending the limits of Turing computability, in T. Hida, K. Saito, S. Si (ed.). Quantum Information Complexity. Proceedings of Meijo Winter School 2003, World Scientific, Singapore, 2004, 119-137.

  12. C. S. Calude, S. Marcus. Mathematical proofs at a crossroad?, in J. Karhumaki, H. Maurer, G. Paun, G. Rozenberg (eds.). Theory Is Forever, Lectures Notes in Comput. Sci. 3113, Springer-Verlag, Berlin, 2004, 15-28. Reprinted in S. Marcus. Words and Languages Everywhere, Polimetrica, Milano, 2007, 89-102.

  13. J.J. Arulanandham,C.S. Calude, M.J. Dinneen. Balance machines: Computing = balancing, in N. Jonoska, G. Paun, G. Rozenberg (eds.). Aspects of Molecular Computing, Lectures Notes in Comput. Sci. 2933, Springer-Verlag, Berlin, 2003, 36-47.

  14. C. S. Calude, L. Staiger. Generalisations of disjunctive sequences, in V. Bratka, M. Schroder, K. Weihrauch, N. Zhong (eds.). Computability and Complexity in Analysis, Informatik Berichte 302-8 FernUniversitat in Hagen, 2003, 153-162.

  15. C. S. Calude, B. Pavlov. The Poincare-Hardy inequality on the complement of a Cantor set, in D. Alpay, I. Gohberg, V. Vinnikov (eds.). Interpolation Theory, Systems Theory and Related Topics, Operator Theory: Advances and Applications, Vol. 134, Birkhauser Verlag, Basel, 2002, 187-208.

  16. C. S. Calude, E. Calude, P. Kay. Liars, demons and chaos, in M. Ito, G. P\u aun, S. Yu (eds.). Words, Semigroups, and Transductions, World Scientific, Singapore, 2001, 33-46.

  17. C. S. Calude, E. Calude, K. Svozil. Computational complementarity for probabilistic automata, in C. Martin-Vide, V. Mitrana (eds.). Where Mathematics, Computer Science, Linguistics and Biology Meet, Kluwer, Amsterdam, 2001, 99-113.

  18. C. S. Calude, H. Jurgensen, S. Legg. Solving finitely refutable mathematical problems, in C. S. Calude, G. P\u{a}un (eds.). Finite Versus Infinite. Contributions to an Eternal Dilemma, Springer-Verlag, London, 2000, 39-52.

  19. C. S. Calude, R. J. Coles. Program-size complexity of initial segments and domination relation reducibility, in J. Karhumaki, H. A. Maurer, G. P\u{a}un, G. Rozenberg (eds.). Jewels Are Forever, Springer-Verlag, Berlin, 1999, 225-237. (invited)

  20. C. S. Calude, R. Coles, P. H. Hertling and B. Khoussainov. Degree-theoretic aspects of computably enumerable reals, in S. B. Cooper, J. K. Truss (eds.). Models and Computability, Cambridge University Press, Cambridge, 1999, 23-39.

  21. C. Calude. Computability and information, in E. Craig (ed.). Routledge Encyclopedia of Philosophy, Routledge, London, Vol. 2 (1998), 477-482. (invited)

  22. C. Calude, J. Hromkovic. Complexity: a language-theoretic point of view, in G. Rozenberg, A. Salomaa (eds.). Handbook of Formal Languages, Vol. II, Springer-Verlag, Berlin, 1997, 1-60. (invited)

  23. C. Calude, H. Maurer. Pocket mathematics, in Gh. Paun (ed.). Mathematical Aspects of Natural and Formal Languages, Scientific World, Singapore, 1994, 13-41. (invited)

  24. C. Calude, I. Chitescu. Complexity: a source of randomness, Modern Problems in Mathematical Research, Vol.1, Bucharest University, Bucharest, 1990, 165-202. Also in C. Calude (ed.). How to Cope with Complexity, Ed. Academiei, Bucharest, 1993, 34-57. (in Romanian)

  25. C. Calude. Meanings and texts: an algorithmic metaphor, in M. Balat, J. Deledalle-Rhodes (eds.). Signs of Humanity, Mouton de Gruyter, 1992, 95-97.

  26. C. Calude. Godel's theorem, a limit of formalization?, The Book of Interferences, Ed. stiintifica si enciclopedica, Bucharest, 1985, 63-68. (in Romanian)

  27. C. Calude, Gh. Paun. On the adequacy of a grammatical model of the brain, in M. Draganescu (ed.). Artificial Intelligence and Robotics, Ed. Academiei, Bucharest, 1983, 45-50. (in Romanian)

  28. C. Calude, Gh. Paun. The absence of contextual ambiguities in the programming languages Fortran and Assiris, in S. Marcus (ed.). Contextual Ambiguities in Natural and Artificial Languages, Comm. & Cognition, Vol. 2, Ghent, Belgium, 1983, 57-76.

  29. C. Calude, S. Marcus, Gh. Paun. Empirical Information and Theoretical Constructs in the Study of Needs II, in S. Marcus (ed.). Mathematical Methods in the Development Problematique, Ed. Academiei, Bucharest, 1982, 39-59. (in Romanian)

  30. C. Calude, Constantin Calude. Mathematical modeling and systemic approach in juridical sciences, in M. Malita (ed.). Systems in Social Sciences, Ed. Academiei, Bucharest, 1977, 105-109. (in Romanian)