{'fraction_non_alphanumeric': 0.02032520325203252, 'fraction_numerical': 0.0, 'mean_word_length': 5.566666666666666, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Automatic Frequency Assignment for Cellular Telephones Using Constraint Satisfaction Techniques

We study the problem of automatic frequency assignment for cellular telephone 
systems. The frequency assignment problem is viewed as the problem 
to minimize the unsatisfied soft constraints in a constraint satisfaction problem 
(CSP) over a finite domain of frequencies involving co-channel, adjacent 
channel, and co-site constraints. The soft constraints are automatically derived 
from signal strength prediction data. The CSP is solved using a generalized 
graph coloring algorithm. Graph-theoretical results play a crucial 
role in making the problem tractable. Performance results from a real-world 
frequency assignment problem are presented. 
We develop the generalized graph coloring algorithm by stepwise refinement, 
starting from DSATUR and augmenting it with local propagation, 
constraint lifting, intelligent backtracking, redundancy avoidance, and iterative 
deepening.