1994

• Iterative devices generating infinite words. Intern. J. Found. Comput. Sci. 5 (1994), 69-97 (with K. Culik II); preliminary version in Springer Lecture Notes in Computer Science 577, 531-544, 1992. (1)
• Finite automata computing real functions. SIAM J. Comp. 23, 789-814, 1994 (with K. Culik II). (1)
• Comparing descriptive and computational complexity of infinite words. Springer Lecture Notes in Computer Science 812, 1994, 169-182 (with A. Lepistö and J. Hromkovic). (2)
• On continous functions computed by finite automata. RAIRO Theoret. Inform. 28 (1994), 387-404 (with D. Derencourt, M. Latteux and A. Terlutte). (1)
• On the defect effect of many identities in free semigroups. In: Gh. Paun (ed.), Mathematical Aspects of Natural and Formal Languages, World-Scientific, 1994, 225-233 (with W. Plandowski). (2)

1995

• Polynomial size test sets for context-free languages. Journal of Computer and System Sciences 50 (1995) 11-19 (with W. Plandowski and W. Rytter); preliminary version in Springer Lecture Notes in Computer Science 623, 53-64, 1992. (1)

1996

• On the size of independent systems of equations in semigroups. Theoret. Comput. Sci. 168 (1996), 105-119 (with W. Plandowski); preliminary version in Springer Lecture Notes in Computer Science 841, 443-452, 1994. (1)
• On computational power of weighted finite automata. Fundamenta Informatica 25 (1996), 285-293 (with D. Derencourt, M. Latteux and A. Terlutte); preliminary version in Springer Lecture Notes in Computer Science 629, 236-245, 1992. (1)
• Borders of Fibonacci strings. J. Comb. Math. & Comb. Comp. 20 (1996), 81-87 (with L. J. Cummings and D. Taylor). (1)
• Remarks on generalized Post Correspondence Problem. Springer Lecture Notes in Computer Science 1046, 39-48, 1996 (with T. Harju and D. Krob). (1) [Abstract]

1997

• Two lower bounds on complexity of infinite words. In: Gh. Paun and A. Salomaa (eds.), New Trends in Formal Languages, Springer Lecture Notes in Computer Science 1218, 366-375, 1997 (with J. Hromkovic); preliminary version in Proceedings of 13th IFIP conference Vol. 1, North-Holland, 479-484, 1994. (2) [Abstract]
• Compactness of systems of equations in semigroups. Int. J. Alg. & Comp. 7 (1997), 457-470 (with T. Harju and W. Plandowski); preliminary version in Springer Lecture Notes in Computer Science 944, 444-454, 1995. (1)
• Toeplitz words, generalized periodicity and periodically iterated morphisms. Eur. J. Comb. 18 (1997), 497-510 (with J. Cassaigne); preliminary version in Springer Lecture Notes in Computer Science 959, 244-254, 1995. (1)
• Morphisms. In: G. Rozenberg and A. Salomaa (eds.), Handbook of Formal Languages Vol. 1, Springer, 1997, 439-510 (with T. Harju). (5) [Abstract]
• Combinatorics of Words. In: G. Rozenberg and A. Salomaa (eds.), Handbook of Formal Languages Vol. 1, Springer, 1997, 329-438 (with C. Choffrut). (5) [Summary]
• A note on decidability questions of word semigroups. Theoret. Comput. Sci. 183 (1997), 83-92 (with C. Choffrut and T. Harju). (1) [Abstract]
• Compactness of systems of equations on completely regular semigroups. In: J. Mycielski, G. Rozenberg and A. Salomaa (eds.), Structures and Logic in Computer Science, Springer Lecture Notes in Computer Science 1281, 268-280, 1997 (with T. Harju and M. Petrich). (2)
• A lower bound for a constant in Shallit´s conjecture, in: S. Bozapalidis (ed.) Developments in Language Theory 103-118, Aristotle University of Thessaloniki, 1997 (with F. Mignosi and W. Plandowski). (2)

1998

• Examples of undecidable problems for 2-generator matrix semigroups. In the special issue of Theoret. Comput. Sci. dedicated to M. P. Schützenberger, 204 (1998), 29-34 (with J. Cassaigne). (1) [Abstract]

1999

• On the complexity of computing the order of repetition in a string, Proceedings of DLT, World Scientific 2000, 178-184 (with W. Plandowski and W. Rytter). (2)
• On the undecidability of the freeness of matrix semigroups. In the special issue of Int. J. Alg. & Comp. dedicated to memory of M. P. Schützenberger, 9 (1999), 295-305. (with J. Cassaigne and T. Harju). (1) [Abstract]
• Generalized factorizations of words and their algorithmic properties, a special issue of Theoret. Comput. Sci. on "Words" 218, (1999), 123-133 (with W. Plandowski and W. Rytter). (1)
• The defect effect of trees, Fundamenta Informaticae 38 (1999), 119-133; Preliminary version in Proceedings of DLT, World Scientific 2000, 164-177 (with Sabrina Mantaci). (1)
• On the equivalence problem of finite substitution and transducers, in J. Karhumäki, H. Maurer, Gh. Paun, G. Rozenberg (eds.), Jewels are Forever, Contributions on Theoretical Computer Science in Honor of Arto Salomaa, Springer (1999) pp. 96-107 (with L. P. Lisovik). (2)

2000

• D0L Sequences, an invited chapter in The Kluwer Encyclopaedia of Mathematics, Kluwer, Dordrecht (2000), 141-142. (1)
• Pattern matching problems for 2-dimensional images described by finite automata. Nordic Journal of Computing 7 (2000), 1-13; preliminary version in Springer Lecture Notes in Computer Science 1279, 245-256, 1997 (with W. Plandowski and W. Rytter). (1) [Abstract]
• On expressibility of languages and relations by word equations. JACM 47 (2000) 483 - 505; preliminary version in Springer Lecture Notes in Computer Science 1256, 98-109, 1997 (with F. Mignosi and W. Plandowski). (1)
• On Fatou properties of rational languages, in C. Martin-Vide and V. Mitrana (eds), Where Mathematics, Computer Science, Linguistics and Biology Meet, Kluwer, Dordrecht, 2000 (with C. Choffrut). (2)
• Some open problems on combinatorics of words and related areas, Proceedings of Algebraic Systems, Formal Languages and Computations, RIMS Proceedings 1166, Research Institute for Mathematical Sciences, 2000, 118-130. (2)

2001

• On conjugacy of languages, Theoret. Informatics and Appl. 35 (2001) 535-550 (with J. Cassaigne and J. Manuch). (1)
• On combinatorial and computational problems on finite sets of words, Springer Lecture Notes in Computer Science 2055 (2001) 69-81. (2)
• Challenges of commutation: An advertisement, Springer Lecture Notes in Computer Science 2138 (2001) 15-23. (2)
• On the expressibility of languages by word equations with a bounded number of variables, Bull. Belg. Math. Soc. 8 (2001) 293-305 (with F. Mignosi and W. Plandowski). (1)

2002

• Branching point approach to Conway's problem, Springer Lecture Notes in Computer Science 2300 (2002) 69-76 (with I. Petre). (2)
• The commutation of finite sets: a challenging problem, Theoret. Comput. Sci. 273 (2002), 69-79. (with C. Choffrut and N. Ollinger) (1)
• Multiple factorizations of words and defect effect, Theoret. Comput. Sci 273 (2002) 81-97. (with J. Manuch). (1)
• Application of finite automata, Springer Lecture Notes in Computer Science 2420 (2002) 40-58. (Invited talk in MFCS 02) (1)
• A note on synchronized automata and road coloring problem, IJFCS 13 (2002), 459-471; preliminary version in Proceedings of DLT 2001, 171-182 (with K. Culik II and J. Kari). (1)
• Decision questions in semilinearity and commutation, JCSS 65: 278-294 (2002); preliminary version in Springer Lecture Notes in Computer Science 2067 (2001) 579-590, (Under the title: Decision questions concerning semilinearity, morphisms and commutation of languages) (with T. Harju, O. Ibarra, and A. Salomaa). (1)
• Independent systems of equations, an invited chapter 14 in M. Lothaire, Algebraic combinatorics on words, J. Berstel and D. Perrin (eds.) Cambridge University Press, (2002), 443-472. (with T. Harju and W. Plandowski). (1)
• Computing partial information out of intractable one - The first digit of 2ⁿ at base 3 as an example, LNCS 2420 (Proceedings of MFCS 2002), 319-327. (2002) (with M. Hirvensalo)
• Communication complexity method for measuring nondeterminism in finite automata, Information and Computation 172: 202-217. (2002); preliminary version in Proceedings of ICALP 00, Lecture Notes in Computer Science 1853 (2000), 199-210 (Under the title: Measures of Nondeterminism in Finite Automata) (2000), (with J. Hromkovic, H. Klauck, G. Schnitger and S. Seibert). (1)
• Locally periodic versus globally periodic infinite words. Journal of Combinatorial Theory 100: 250-264, (2002); preliminary version in Springer Lecture Notes of Computer Science 1443, 1998, 421-430. (with A. Lepistö and W. Plandowski). (1)
• Conway's problem for three-word sets, Theoretical Computer Science 289: 705-725, (2002); preliminary version in Proceedings of ICALP 00, Lecture Notes in Computer Science 1853, (2000), 536-546, (Under the title: On the centralizer of a finite set) (with I. Petre). (1)

2003

• A defect theorem for bi-infinite words, Theoretical Computer Science 292(1): 237-243, (2003); preliminary version in Springer Lecture Notes in Computer Science 1450 (1998), 674-682 (Under the title: On defect effect of bi-infinite words) (with J. Manuch and W. Plandowski). (1)
• The Complexity of compressing subsegments of images described by finite automata, Discrete Appl. Math 125(2-3): 235-254, (2003); preliminary version in Springer Lecture Notes in Computer Science 1645 (1999) pp. 189-196, Proceedings of Combinatorial Pattern Matching (Under the title: The compression of subsegments of images described by finite automata) (with W. Plandowski and W. Rytter). (1)
• Decidability of binary infinite Post Correspondence Problem, Discret Appl. Math. 130 (203), 521-526 (with V. Halava and T. Harju)
• Combinatorics on Words - A tutorial, Bull. EATCS, 79 (2003), 178-229; also in Current Trends in Theoretical Computer Science. The Challenge of the New Century, Gh. Paun, G. Rozenberg, A. Salomaa (eds.), World Scientific, Singapore, 2004, 415-476. (with J. Berstel) (2)
• Computing partial information out of intractable: Powers of algebraic numbers as an example, manuscript, 31 pp. (with M. Hirvensalo and A. Rabinovich) (6)
• (G)PCP for words of length two, manuscript (with V. Halava, T. Harju and M. Hirvensalo) (6)
• Equations over finite sets of words: observations and open problems, manuscript (with J. Cassaigne) (6)
• The equivalence problem for finite substitutions on ab*c, with applications, IJFCS 14 (2003), 699-710; preliminary version in Springer Lecture Notes in Computer Science 2380, (2002), 812-820 (with L. Lisovik) (1)
• A simple undecidable problem: The inclusion problem for finite substitutions on ab*c, Information and Computation 187 (2003), 40-48; preliminary version in Lecture Notes in Computer Science 2010 (2001), 388-395 (with L.P. Lisovik), (1).
• Automata on words, Proceedings of CIAA, LNCS 2759 (2003), 3-10, (2).

2004

• Freeness of multiplicative matrix semigroups, in V. Blondel and A. Megretski(eds), Unsolved Problems in Mathematical System and Control Theory, Princeton University Press, (Princeton, New Jersey) (2004), 309-314, (with V. Blondel and J. Cassaigne) (1)
• Combinatorics on Infinite Words, in C. Martin-Vide, V. Mitrana, Gh. Paun (eds.), Formal Languages and Applications, Stud. Fuzziness Soft. Comput. 148, Springer, Berlin, 2004, 393-413 (with A. Lepistö) (2)
• Many aspects of defect theorem, a special issue of Theoret. Comput. Sci. 324, (2004), 35-54 (with T. Harju). (1)
• On the complexity of decidable cases of commutation problem for languages, Theoret. Comput. Sci. (to appear); preliminary version in: Springer Lecture Notes of Computer Science 2138 (2001) 193-203 (with W. Plandowski and W. Rytter). (1)
• Sanat ja automaatit, Tietojenkäsittelytieteen Seuran 30-vuotis juhlakirjassa (ilmestyy), 31 s. (2)
• The commutation with codes and ternary sets of words, Theory of Computing Systems (to appear); preliminary version in: Proceedings of STACS, LNCS 2607, (2003), 74-84; (with M. Latteux and I. Petre) (1)
• Polynomial versus exponential growth in repetition free binary words, J. Comb. Theory A 105, (2004), 335-347 (with J. Shallit) (1)
• Fixed point approach to commutation of languages, in N. Jonoska, Gh. Paun, G. Rozenberg (eds.), Aspects of Molecular Computing, -- Essays dedicated to Tom Head on the occasion of His 70th Birthday, LNCS 2950, Festschrift (2004) (with K. Culik II and P. Salmela), (2).
• On Some Special Equations on Words, Preproceedings of JM, Univ. of Liège, (2004), 208-227. (with E. Petre), (2).
• Two Problems on Commutation of Languages, in: G. Rozenberg and A. Salomaa, Recent Trends in Theoretical Computer Science, World Scientific Singapore, 2004, 477-493. (with I. Petre) (2)
• Combinatorics on Words: A New Challenging Topic, in: M. Abel (eds) Proceeding of FINNEST (2004), (to appear), (2).

2005

• Finite sets of words and computing (a survey), LNCS 3354, (Proceedings of MCU04), (2005), 36-49, (2).
• Some decision problems on integer matrices, (with C. Choffrut) Theoretical Informatics and Applications (March, 2005), (1).
• Commutation with codes, Theoret. Comput. Sci. (to appear) (with M. Latteux and I. Petre), (1).