Content deleted Content added
Line 245:
'''The Erosion Lemma (Wehrung, preprint 2005).'''
Let ''x''<sub>0</sub>, ''x''<sub>1</sub> in ''L'' and let <math>Z=\{z_0,z_1,\dots,z_n\}</math>, for a positive integer ''n'', be a finite subset of ''L'' with <math>\bigvee_{i<n}z_i\leq z_n</math>. Put
:<math>\alpha_j=\bigvee(\Theta_L(z_i,z_{i+1})\mid i<n,\ \varepsilon(i)=j),\text{ for all }j<2.</math>
Then there are congruences <math>\theta_j\in\mathrm{Con_c}^{\{x_j\}\vee Z}L</math>, for ''j<2'', such that
:<math> z_0\vee x_0\vee x_1\equiv z_n\vee x_0\vee x_1
| |||