Browsing by Subject "Formal languages."

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Capacity of noisy, discrete memoryless channels under input constraints
(1990) Karaşan, Ezhan
In this thesis work, we examine the capacity of discrete memoryless channels under input constraints. We consider a certain class of input-restricted channels for which constrained sequences can be modeled as outputs of a finite-state machine(FSM). No efficient algorithm is known for computing the capacity of such a channel. For the noiseless case, i.e., when the channel input letter and the corresponding output letter are identical, it is shown that [1] the channel capacity is the logarithm of the largest eigenvalue of the adjacency matrix of the state-transition diagram of the FSM generating the allowed channel input sequences. Furthermore, the probability distribution on the input sequences achieving the channel capacity is first-order markovian. Here, we discuss the noisy case. For a specific input-restricted channel, we show that unlike the noiseless case, the capacity is no longer achieved by a first-order distribution. We derive upper and lower bounds on the maximum rate achievable by a K-th order markovian distribution on the allowed input sequences. The computational results show that the second-order distribution does strictly better than the first-order distribution for this particular channel. A sequence of upper bounds on the capacity of an input-restricted channel is also given. We show that this sequence converges to the channel capacity. The numerical results clarify that markovian distribution may achieve rates close to the capacity for the channel considered in this work.
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A shape grammar model for Anatolian madrasah architecture
(1999) Tekin, Senem
This thesis explores the role and potential of computational tools in the analysis of an existing corpus of work and synthesis of new designs. The research would like to demonstrate that, the basic grammar rules underlying the composition can be described by analyzing a set of similar designs, and new designs can be derived based on the extracted rules. Examples of Anatolian madrasahs from Anatolian region of Turkey have been chosen as a research corpus. The body of research is limited to Anatolian madrasahs that were built in the period of XII and XIII centuries having morphological similarities. After an initial evaluation of the material gathered from Kuran (1969) and Sozen (1970, 1972), in the first step, common features in plan composition are described within a research body. A classification for the plan types of the madrasahs is established. The location of main components like court, iwan(s), and other rooms are a major factor at the classification stage. The next step is the introduction of a shape grammar system for generating the plan layouts of Anatolian madrasahs through a number of rules by using the main plan components and their spatial relations. In the final step, a simple interpreter is developed by using the programming language AutoLisp for the representation of the shape grammar system for Anatolian madrasahs. The shape grammar system is realized in computer-aided design (CAD) environment to present an automated mechanism for generating different designs of Anatolian madrasahs through these rules. Such computational tools provide easy and flexible manipulation of objects so that many compositions can be created.