David Wahlstedt

• Phd
• Ericsson

We study a variation of Nim-type subtraction games, called Cumulative Subtraction (CS). Two players alternate in removing pebbles out of a joint pile, and their actions add or remove points to a common score. We prove that the zero-sum outcome in optimal play of a CS with a finite number of possible actions is eventually periodic, with period $2s$,...

We study zero-sum games, a variant of the classical combinatorial Subtraction games (studied for example in the monumental work `Winning Ways', by Berlekamp, Conway and Guy), called Cumulative Subtraction (CS). Two players alternate in moving, and get points for taking pebbles out of a joint pile. We prove that the outcome in optimal play (game val...

Disjunctive well-foundedness (used in Terminator), size-change termination, and well-quasi-orders (used in supercompilation and term-rewrite systems) are examples of techniques that have been successfully applied to automatic proofs of program termination and online termination testing, respectively. Although these works originate in different comm...

We present a variation of Martin-Löf’s logical framework with βι-equality, extended with first-order parameterized algebraic data types and recursive pattern-matching definitions. Our contribution is a proof of normalization for the proposed system, from which we ob- tain decidable type-correctness. Our result holds under the assump- tion that the...

Abstract We prove normalization for a dependently typed lambda-calculus extended with first-order data types and computation schemata for first-order size-change terminating recursive functions. Size-change termination, introduced by C.S. Lee, N.D. Jones and A.M. Ben- Amram, can be seen as a generalized form of structural induction, which allows in...