Plotting Running Times of SAT solver In the the paper "Efficient Methods for Conversion and Solution of Sparse Systems of Low-Degree Multivariate Polynomials over GF(2) via
SAT-Solvers" there is a Figure that I can not understand and I need help to understand it. The authors plot the running time of the probability distribution of the SAT solver applied to a certain problem. My question is about the X axis. Why there are numbers in this Figure 1, that are placed in vertical form? How to interpret this axis X?

I imagine that are interval times but I do not understand why they are in vertical form. Moreover, on the same axis there are twice the number 180.
Disclaimer: I'm answering without any knowledge on the content of the paper in question.


  Why there are numbers in this Figure 1, that are placed in vertical form? 


Because otherwise the figure would not fit into the page width (or the authors would have to use unreadably small font).


  How to interpret this axis X?
  I imagine that are interval times but I do not understand why they are in vertical form. Moreover, on the same axis there are twice the number 180.


What you imagine is most probably correct. The vertical form I explained above. This is not 180 but 1800 (the second time). After 990 goes 1030, not 103. The last zero is either lost or simply omitted to save space because it is assumed to be obvious for a reader that "After 990 goes 1030, not 103".